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  • IBM HS23 Blade Server (7875) onboard NIC driver for linux

    - by Igor Spivak
    I work with IBM HS23 Blade Server (7875). It's onboard NIC adapter is: Emulex OCl11104-F-X Virtual Fabric Adapter 2-port 10GB and 2-port 1GB LOM . I'm tryed to the following Linux OS with the server: 2.6.32-22-generic-pae #36-Ubuntu SMP. and discovered my OS has not proper Network drive installed (for the NIC adapter described above). After investigation I made, I discovered that the driver I need is "be2net" placed in "net" directory of the linux under the folder "be2net". I managed to download this driver with the latest package for my kernel. Driver info ("modinfo be2net" result) is as follows: --------------------------------------------------------------------------------------- filename: /lib/modules/2.6.32-22-generic-pae/kernel/drivers/net/benet/be2net.ko license: GPL author: ServerEngines Corporation description: ServerEngines BladeEngine2 10Gbps NICDriver 2.101.205 version: 2.101.205 srcversion: 199ADD251CB874C3727CC47 alias: pci:v000019A2d00000710sv*sd*bc*sc*i* alias: pci:v000019A2d00000701sv*sd*bc*sc*i* alias: pci:v000019A2d00000700sv*sd*bc*sc*i* alias: pci:v000019A2d00000221sv*sd*bc*sc*i* alias: pci:v000019A2d00000211sv*sd*bc*sc*i* depends: vermagic: 2.6.32-22-generic-pae SMP mod_unload modversions 586TSC parm: rx_frag_size:Size of a fragment that holds rcvd data. (uint) --------------------------------------------------------------------------------------- After starting linux, I get the following error: be2net 0000:16:00.x: Emulex OneConnect 10Gbps NIC (be3) initilization failed. I checked the same server with another Linux version (Red-Had 5.5.1.0) and the NICs worked properly, so seems there is no problem in HW. Also, on IBM or Emulex offical sites I managed to find drivers only for Red-Had and SUSE versions.

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  • Big Data – Role of Cloud Computing in Big Data – Day 11 of 21

    - by Pinal Dave
    In yesterday’s blog post we learned the importance of the NewSQL. In this article we will understand the role of Cloud in Big Data Story What is Cloud? Cloud is the biggest buzzword around from last few years. Everyone knows about the Cloud and it is extremely well defined online. In this article we will discuss cloud in the context of the Big Data. Cloud computing is a method of providing a shared computing resources to the application which requires dynamic resources. These resources include applications, computing, storage, networking, development and various deployment platforms. The fundamentals of the cloud computing are that it shares pretty much share all the resources and deliver to end users as a service.  Examples of the Cloud Computing and Big Data are Google and Amazon.com. Both have fantastic Big Data offering with the help of the cloud. We will discuss this later in this blog post. There are two different Cloud Deployment Models: 1) The Public Cloud and 2) The Private Cloud Public Cloud Public Cloud is the cloud infrastructure build by commercial providers (Amazon, Rackspace etc.) creates a highly scalable data center that hides the complex infrastructure from the consumer and provides various services. Private Cloud Private Cloud is the cloud infrastructure build by a single organization where they are managing highly scalable data center internally. Here is the quick comparison between Public Cloud and Private Cloud from Wikipedia:   Public Cloud Private Cloud Initial cost Typically zero Typically high Running cost Unpredictable Unpredictable Customization Impossible Possible Privacy No (Host has access to the data Yes Single sign-on Impossible Possible Scaling up Easy while within defined limits Laborious but no limits Hybrid Cloud Hybrid Cloud is the cloud infrastructure build with the composition of two or more clouds like public and private cloud. Hybrid cloud gives best of the both the world as it combines multiple cloud deployment models together. Cloud and Big Data – Common Characteristics There are many characteristics of the Cloud Architecture and Cloud Computing which are also essentially important for Big Data as well. They highly overlap and at many places it just makes sense to use the power of both the architecture and build a highly scalable framework. Here is the list of all the characteristics of cloud computing important in Big Data Scalability Elasticity Ad-hoc Resource Pooling Low Cost to Setup Infastructure Pay on Use or Pay as you Go Highly Available Leading Big Data Cloud Providers There are many players in Big Data Cloud but we will list a few of the known players in this list. Amazon Amazon is arguably the most popular Infrastructure as a Service (IaaS) provider. The history of how Amazon started in this business is very interesting. They started out with a massive infrastructure to support their own business. Gradually they figured out that their own resources are underutilized most of the time. They decided to get the maximum out of the resources they have and hence  they launched their Amazon Elastic Compute Cloud (Amazon EC2) service in 2006. Their products have evolved a lot recently and now it is one of their primary business besides their retail selling. Amazon also offers Big Data services understand Amazon Web Services. Here is the list of the included services: Amazon Elastic MapReduce – It processes very high volumes of data Amazon DynammoDB – It is fully managed NoSQL (Not Only SQL) database service Amazon Simple Storage Services (S3) – A web-scale service designed to store and accommodate any amount of data Amazon High Performance Computing – It provides low-tenancy tuned high performance computing cluster Amazon RedShift – It is petabyte scale data warehousing service Google Though Google is known for Search Engine, we all know that it is much more than that. Google Compute Engine – It offers secure, flexible computing from energy efficient data centers Google Big Query – It allows SQL-like queries to run against large datasets Google Prediction API – It is a cloud based machine learning tool Other Players Besides Amazon and Google we also have other players in the Big Data market as well. Microsoft is also attempting Big Data with the Cloud with Microsoft Azure. Additionally Rackspace and NASA together have initiated OpenStack. The goal of Openstack is to provide a massively scaled, multitenant cloud that can run on any hardware. Thing to Watch The cloud based solutions provides a great integration with the Big Data’s story as well it is very economical to implement as well. However, there are few things one should be very careful when deploying Big Data on cloud solutions. Here is a list of a few things to watch: Data Integrity Initial Cost Recurring Cost Performance Data Access Security Location Compliance Every company have different approaches to Big Data and have different rules and regulations. Based on various factors, one can implement their own custom Big Data solution on a cloud. Tomorrow In tomorrow’s blog post we will discuss about various Operational Databases supporting Big Data. Reference: Pinal Dave (http://blog.sqlauthority.com) Filed under: Big Data, PostADay, SQL, SQL Authority, SQL Query, SQL Server, SQL Tips and Tricks, T SQL

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  • SQL SERVER – Guest Post by Sandip Pani – SQL Server Statistics Name and Index Creation

    - by pinaldave
    Sometimes something very small or a common error which we observe in daily life teaches us new things. SQL Server Expert Sandip Pani (winner of Joes 2 Pros Contests) has come across similar experience. Sandip has written a guest post on an error he faced in his daily work. Sandip is working for QSI Healthcare as an Associate Technical Specialist and have more than 5 years of total experience. He blogs at SQLcommitted.com and contribute in various forums. His social media hands are LinkedIn, Facebook and Twitter. Once I faced following error when I was working on performance tuning project and attempt to create an Index. Mug 1913, Level 16, State 1, Line 1 The operation failed because an index or statistics with name ‘Ix_Table1_1′ already exists on table ‘Table1′. The immediate reaction to the error was that I might have created that index earlier and when I researched it further I found the same as the index was indeed created two times. This totally makes sense. This can happen due to many reasons for example if the user is careless and executes the same code two times as well, when he attempts to create index without checking if there was index already on the object. However when I paid attention to the details of the error, I realize that error message also talks about statistics along with the index. I got curious if the same would happen if I attempt to create indexes with the same name as statistics already created. There are a few other questions also prompted in my mind. I decided to do a small demonstration of the subject and build following demonstration script. The goal of my experiment is to find out the relation between statistics and the index. Statistics is one of the important input parameter for the optimizer during query optimization process. If the query is nontrivial then only optimizer uses statistics to perform a cost based optimization to select a plan. For accuracy and further learning I suggest to read MSDN. Now let’s find out the relationship between index and statistics. We will do the experiment in two parts. i) Creating Index ii) Creating Statistics We will be using the following T-SQL script for our example. IF (OBJECT_ID('Table1') IS NOT NULL) DROP TABLE Table1 GO CREATE TABLE Table1 (Col1 INT NOT NULL, Col2 VARCHAR(20) NOT NULL) GO We will be using following two queries to check if there are any index or statistics on our sample table Table1. -- Details of Index SELECT OBJECT_NAME(OBJECT_ID) AS TableName, Name AS IndexName, type_desc FROM sys.indexes WHERE OBJECT_NAME(OBJECT_ID) = 'table1' GO -- Details of Statistics SELECT OBJECT_NAME(OBJECT_ID) TableName, Name AS StatisticsName FROM sys.stats WHERE OBJECT_NAME(OBJECT_ID) = 'table1' GO When I ran above two scripts on the table right after it was created it did not give us any result which was expected. Now let us begin our test. 1) Create an index on the table Create following index on the table. CREATE NONCLUSTERED INDEX Ix_Table1_1 ON Table1(Col1) GO Now let us use above two scripts and see their results. We can see that when we created index at the same time it created statistics also with the same name. Before continuing to next set of demo – drop the table using following script and re-create the table using a script provided at the beginning of the table. DROP TABLE table1 GO 2) Create a statistic on the table Create following statistics on the table. CREATE STATISTICS Ix_table1_1 ON Table1 (Col1) GO Now let us use above two scripts and see their results. We can see that when we created statistics Index is not created. The behavior of this experiment is different from the earlier experiment. Clean up the table setup using the following script: DROP TABLE table1 GO Above two experiments teach us very valuable lesson that when we create indexes, SQL Server generates the index and statistics (with the same name as the index name) together. Now due to the reason if we have already had statistics with the same name but not the index, it is quite possible that we will face the error to create the index even though there is no index with the same name. A Quick Check To validate that if we create statistics first and then index after that with the same name, it will throw an error let us run following script in SSMS. Make sure to drop the table and clean up our sample table at the end of the experiment. -- Create sample table CREATE TABLE TestTable (Col1 INT NOT NULL, Col2 VARCHAR(20) NOT NULL) GO -- Create Statistics CREATE STATISTICS IX_TestTable_1 ON TestTable (Col1) GO -- Create Index CREATE NONCLUSTERED INDEX IX_TestTable_1 ON TestTable(Col1) GO -- Check error /*Msg 1913, Level 16, State 1, Line 2 The operation failed because an index or statistics with name 'IX_TestTable_1' already exists on table 'TestTable'. */ -- Clean up DROP TABLE TestTable GO While creating index it will throw the following error as statistics with the same name is already created. In simple words – when we create index the name of the index should be different from any of the existing indexes and statistics. Reference: Pinal Dave (http://blog.SQLAuthority.com) Filed under: PostADay, SQL, SQL Authority, SQL Error Messages, SQL Index, SQL Query, SQL Server, SQL Tips and Tricks, T SQL, Technology Tagged: SQL Statistics

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  • APC fragmention woes on Apache AWS EC2 Small instance with WordPress and W3TC

    - by two7s_clash
    AWS EC2 Small instance, Apache 2 running WordPress and W3TC. Within an hour, my APC fragmentation hits 100%. My APC settings are: apc.enabled = 1 apc.shm_segments = 1 apc.shm_size = 100M apc.optimization = 0 apc.num_files_hint = 512 apc.user_entries_hint = 1024 apc.ttl = 7200 apc.user_ttl = 7200 apc.gc_ttl = 3600 apc.cache_by_default = 1 apc.use_request_time = 1 apc.filters = "apc\.php$" apc.mmap_file_mask = "/tmp/apc.XXXXXX" apc.slam_defense = 0 apc.file_update_protection = 2 apc.enable_cli = 0 apc.max_file_size = 2M apc.stat = 1 apc.write_lock = 1 apc.report_autofilter = 0 apc.include_once_override = 0 apc.rfc1867 = 0 apc.rfc1867_prefix = "upload_" apc.rfc1867_name = "APC_UPLOAD_PROGRESS" apc.rfc1867_freq = 0 apc.localcache = 0 apc.localcache.size = 256M apc.coredump_unmap = 0 apc.stat_ctime = 0 apc.canonicalize = 1 apc.lazy_functions = 0 apc.lazy_classes = 0 /etc/php.d/apc.ini More poop can be seen here. Mostly cribed settings from here. The shm was meant to be whittled down from such a high value after some observation, but apparently such a large value isn't even high enough.... I found an similar question/answer here. I do have some virtual hosts setup, but they aren't being touched much at all. Having users logged into the admin panel of WP does make things worse, but that's certainly not the main culprit. The question asker seems to suggest that it turns out W3TC is probably causing the problem, which the plugin author seems to agree with, but there aren't any helpful details beyond that. Why is it causing the problem? Do I just take it for now and turn off object caching with APC? Is there nothing I can do? Does having it turned on without being used for object caching actually help anything? Would memcache be an ok substitute just for object caching here? Finally, maybe I just shouldn't worry so much about the fragmentation?

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  • SQL – Quick Start with Explorer Sections of NuoDB – Query NuoDB Database

    - by Pinal Dave
    This is the third post in the series of the blog posts I am writing about NuoDB. NuoDB is very innovative and easy-to-use product. I can clearly see how one can scale-out NuoDB with so much ease and confidence. In my very first blog post we discussed how we can install NuoDB (link), and in my second post I discussed how we can manage the NuoDB database transaction engines and storage managers with a few clicks (link). Note: You can Download NuoDB from here. In this post, we will learn how we can use the Explorer feature of NuoDB to do various SQL operations. NuoDB has a browser-based Explorer, which is very powerful and has many of the features any IDE would normally have. Let us see how it works in the following step-by-step tutorial. Let us go to the NuoDBNuoDB Console by typing the following URL in your browser: http://localhost:8080/ It will bring you to the QuickStart screen. Make sure that you have created the sample database. If you have not created sample database, click on Create Database and create it successfully. Now go to the NuoDB Explorer by clicking on the main tab, and it will ask you for your domain username and password. Enter the username as a domain and password as a bird. Alternatively you can also enter username as a quickstart and password as a quickstart. Once you enter the password you will be able to see the databases. In our example we have installed the Sample Database hence you will see the Test database in our Database Hierarchy screen. When you click on database it will ask for the database login. Note that Database Login is different from Domain login and you will have to enter your database login over here. In our case the database username is dba and password is goalie. Once you enter a valid username and password it will display your database. Further expand your database and you will notice various objects in your database. Once you explore various objects, select any database and click on Open. When you click on execute, it will display the SQL script to select the data from the table. The autogenerated script displays entire result set from the database. The NuoDB Explorer is very powerful and makes the life of developers very easy. If you click on List SQL Statements it will list all the available SQL statements right away in Query Editor. You can see the popup window in following image. Here is the cool thing for geeks. You can even click on Query Plan and it will display the text based query plan as well. In case of a SELECT, the query plan will be much simpler, however, when we write complex queries it will be very interesting. We can use the query plan tab for performance tuning of the database. Here is another feature, when we click on List Tables in NuoDB Explorer.  It lists all the available tables in the query editor. This is very helpful when we are writing a long complex query. Here is a relatively complex example I have built using Inner Join syntax. Right below I have displayed the Query Plan. The query plan displays all the little details related to the query. Well, we just wrote multi-table query and executed it against the NuoDB database. You can use the NuoDB Admin section and do various analyses of the query and its performance. NuoDB is a distributed database built on a patented emergent architecture with full support for SQL and ACID guarantees.  It allows you to add Transaction Engine processes to a running system to improve the performance of your system.  You can also add a second Storage Engine to your running system for redundancy purposes.  Conversely, you can shut down processes when you don’t need the extra database resources. NuoDB also provides developers and administrators with a single intuitive interface for centrally monitoring deployments. If you have read my blog posts and have not tried out NuoDB, I strongly suggest that you download it today and catch up with the learnings with me. Trust me though the product is very powerful, it is extremely easy to learn and use. Reference: Pinal Dave (http://blog.sqlauthority.com)   Filed under: Big Data, PostADay, SQL, SQL Authority, SQL Query, SQL Server, SQL Tips and Tricks, T SQL, Technology Tagged: NuoDB

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  • SQL SERVER – Solution – Puzzle – Statistics are not Updated but are Created Once

    - by pinaldave
    Earlier I asked puzzle why statistics are not updated. Read the complete details over here: Statistics are not Updated but are Created Once In the question I have demonstrated even though statistics should have been updated after lots of insert in the table are not updated.(Read the details SQL SERVER – When are Statistics Updated – What triggers Statistics to Update) In this example I have created following situation: Create Table Insert 1000 Records Check the Statistics Now insert 10 times more 10,000 indexes Check the Statistics – it will be NOT updated Auto Update Statistics and Auto Create Statistics for database is TRUE Now I have requested two things in the example 1) Why this is happening? 2) How to fix this issue? I have many answers – here is the how I fixed it which has resolved the issue for me. NOTE: There are multiple answers to this problem and I will do my best to list all. Solution: Create nonclustered Index on column City Here is the working example for the same. Let us understand this script and there is added explanation at the end. -- Execution Plans Difference -- Estimated Execution Plan Vs Actual Execution Plan -- Create Sample Database CREATE DATABASE SampleDB GO USE SampleDB GO -- Create Table CREATE TABLE ExecTable (ID INT, FirstName VARCHAR(100), LastName VARCHAR(100), City VARCHAR(100)) GO CREATE NONCLUSTERED INDEX IX_ExecTable1 ON ExecTable (City); GO -- Insert One Thousand Records -- INSERT 1 INSERT INTO ExecTable (ID,FirstName,LastName,City) SELECT TOP 1000 ROW_NUMBER() OVER (ORDER BY a.name) RowID, 'Bob', CASE WHEN  ROW_NUMBER() OVER (ORDER BY a.name)%2 = 1 THEN 'Smith' ELSE 'Brown' END, CASE WHEN ROW_NUMBER() OVER (ORDER BY a.name)%20 = 1 THEN 'New York' WHEN  ROW_NUMBER() OVER (ORDER BY a.name)%20 = 5 THEN 'San Marino' WHEN  ROW_NUMBER() OVER (ORDER BY a.name)%20 = 3 THEN 'Los Angeles' WHEN  ROW_NUMBER() OVER (ORDER BY a.name)%20 = 7 THEN 'La Cinega' WHEN  ROW_NUMBER() OVER (ORDER BY a.name)%20 = 13 THEN 'San Diego' WHEN  ROW_NUMBER() OVER (ORDER BY a.name)%20 = 17 THEN 'Las Vegas' ELSE 'Houston' END FROM sys.all_objects a CROSS JOIN sys.all_objects b GO -- Display statistics of the table sp_helpstats N'ExecTable', 'ALL' GO -- Select Statement SELECT FirstName, LastName, City FROM ExecTable WHERE City  = 'New York' GO -- Display statistics of the table sp_helpstats N'ExecTable', 'ALL' GO -- Replace your Statistics over here DBCC SHOW_STATISTICS('ExecTable', IX_ExecTable1); GO -------------------------------------------------------------- -- Round 2 -- Insert One Thousand Records -- INSERT 2 INSERT INTO ExecTable (ID,FirstName,LastName,City) SELECT TOP 1000 ROW_NUMBER() OVER (ORDER BY a.name) RowID, 'Bob', CASE WHEN  ROW_NUMBER() OVER (ORDER BY a.name)%2 = 1 THEN 'Smith' ELSE 'Brown' END, CASE WHEN ROW_NUMBER() OVER (ORDER BY a.name)%20 = 1 THEN 'New York' WHEN  ROW_NUMBER() OVER (ORDER BY a.name)%20 = 5 THEN 'San Marino' WHEN  ROW_NUMBER() OVER (ORDER BY a.name)%20 = 3 THEN 'Los Angeles' WHEN  ROW_NUMBER() OVER (ORDER BY a.name)%20 = 7 THEN 'La Cinega' WHEN  ROW_NUMBER() OVER (ORDER BY a.name)%20 = 13 THEN 'San Diego' WHEN  ROW_NUMBER() OVER (ORDER BY a.name)%20 = 17 THEN 'Las Vegas' ELSE 'Houston' END FROM sys.all_objects a CROSS JOIN sys.all_objects b GO -- Select Statement SELECT FirstName, LastName, City FROM ExecTable WHERE City  = 'New York' GO -- Display statistics of the table sp_helpstats N'ExecTable', 'ALL' GO -- Replace your Statistics over here DBCC SHOW_STATISTICS('ExecTable', IX_ExecTable1); GO -- Clean up Database DROP TABLE ExecTable GO When I created non clustered index on the column city, it also created statistics on the same column with same name as index. When we populate the data in the column the index is update – resulting execution plan to be invalided – this leads to the statistics to be updated in next execution of SELECT. This behavior does not happen on Heap or column where index is auto created. If you explicitly update the index, often you can see the statistics are updated as well. You can see this is for sure happening if you follow the tell of John Sansom. John Sansom‘s suggestion: That was fun! Although the column statistics are invalidated by the time the second select statement is executed, the query is not compiled/recompiled but instead the existing query plan is reused. It is the “next” compiled query against the column statistics that will see that they are out of date and will then in turn instantiate the action of updating statistics. You can see this in action by forcing the second statement to recompile. SELECT FirstName, LastName, City FROM ExecTable WHERE City = ‘New York’ option(RECOMPILE) GO Kevin Cross also have another suggestion: I agree with John. It is reusing the Execution Plan. Aside from OPTION(RECOMPILE), clearing the Execution Plan Cache before the subsequent tests will also work. i.e., run this before round 2: ————————————————————– – Clear execution plan cache before next test DBCC FREEPROCCACHE WITH NO_INFOMSGS; ————————————————————– Nice puzzle! Kevin As this was puzzle John and Kevin both got the correct answer, there was no condition for answer to be part of best practices. I know John and he is finest DBA around – his tremendous knowledge has always impressed me. John and Kevin both will agree that clearing cache either using DBCC FREEPROCCACHE and recompiling each query every time is for sure not good advice on production server. It is correct answer but not best practice. By the way, if you have better solution or have better suggestion please advise. I am open to change my answer and publish further improvement to this solution. On very separate note, I like to have clustered index on my Primary Key, which I have not mentioned here as it is out of the scope of this puzzle. Reference: Pinal Dave (http://blog.SQLAuthority.com) Filed under: Pinal Dave, PostADay, Readers Contribution, Readers Question, SQL, SQL Authority, SQL Index, SQL Puzzle, SQL Query, SQL Scripts, SQL Server, SQL Tips and Tricks, T SQL, Technology Tagged: Statistics

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  • SQL SERVER – PAGELATCH_DT, PAGELATCH_EX, PAGELATCH_KP, PAGELATCH_SH, PAGELATCH_UP – Wait Type – Day 12 of 28

    - by pinaldave
    This is another common wait type. However, I still frequently see people getting confused with PAGEIOLATCH_X and PAGELATCH_X wait types. Actually, there is a big difference between the two. PAGEIOLATCH is related to IO issues, while PAGELATCH is not related to IO issues but is oftentimes linked to a buffer issue. Before we delve deeper in this interesting topic, first let us understand what Latch is. Latches are internal SQL Server locks which can be described as very lightweight and short-term synchronization objects. Latches are not primarily to protect pages being read from disk into memory. It’s a synchronization object for any in-memory access to any portion of a log or data file.[Updated based on comment of Paul Randal] The difference between locks and latches is that locks seal all the involved resources throughout the duration of the transactions (and other processes will have no access to the object), whereas latches locks the resources during the time when the data is changed. This way, a latch is able to maintain the integrity of the data between storage engine and data cache. A latch is a short-living lock that is put on resources on buffer cache and in the physical disk when data is moved in either directions. As soon as the data is moved, the latch is released. Now, let us understand the wait stat type  related to latches. From Book On-Line: PAGELATCH_DT Occurs when a task is waiting on a latch for a buffer that is not in an I/O request. The latch request is in Destroy mode. PAGELATCH_EX Occurs when a task is waiting on a latch for a buffer that is not in an I/O request. The latch request is in Exclusive mode. PAGELATCH_KP Occurs when a task is waiting on a latch for a buffer that is not in an I/O request. The latch request is in Keep mode. PAGELATCH_SH Occurs when a task is waiting on a latch for a buffer that is not in an I/O request. The latch request is in Shared mode. PAGELATCH_UP Occurs when a task is waiting on a latch for a buffer that is not in an I/O request. The latch request is in Update mode. PAGELATCH_X Explanation: When there is a contention of access of the in-memory pages, this wait type shows up. It is quite possible that some of the pages in the memory are of very high demand. For the SQL Server to access them and put a latch on the pages, it will have to wait. This wait type is usually created at the same time. Additionally, it is commonly visible when the TempDB has higher contention as well. If there are indexes that are heavily used, contention can be created as well, leading to this wait type. Reducing PAGELATCH_X wait: The following counters are useful to understand the status of the PAGELATCH: Average Latch Wait Time (ms): The wait time for latch requests that have to wait. Latch Waits/sec: This is the number of latch requests that could not be granted immediately. Total Latch Wait Time (ms): This is the total latch wait time for latch requests in the last second. If there is TempDB contention, I suggest that you read the blog post of Robert Davis right away. He has written an excellent blog post regarding how to find out TempDB contention. The same blog post explains the terms in the allocation of GAM, SGAM and PFS. If there was a TempDB contention, Paul Randal explains the optimal settings for the TempDB in his misconceptions series. Trace Flag 1118 can be useful but use it very carefully. I totally understand that this blog post is not as clear as my other blog posts. I suggest if this wait stats is on one of your higher wait type. Do leave a comment or send me an email and I will get back to you with my solution for your situation. May the looking at all other wait stats and types together become effective as this wait type can help suggest proper bottleneck in your system. Read all the post in the Wait Types and Queue series. Note: The information presented here is from my experience and there is no way that I claim it to be accurate. I suggest reading Book OnLine for further clarification. All the discussions of Wait Stats in this blog are generic and vary from system to system. It is recommended that you test this on a development server before implementing it to a production server. Reference: Pinal Dave (http://blog.SQLAuthority.com)   Filed under: Pinal Dave, PostADay, SQL, SQL Authority, SQL Query, SQL Scripts, SQL Server, SQL Tips and Tricks, SQL Wait Stats, SQL Wait Types, T SQL, Technology

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  • SQL SERVER – Example of Performance Tuning for Advanced Users with DB Optimizer

    - by Pinal Dave
    Performance tuning is such a subject that everyone wants to master it. In beginning everybody is at a novice level and spend lots of time learning how to master the art of performance tuning. However, as we progress further the tuning of the system keeps on getting very difficult. I have understood in my early career there should be no need of ego in the technology field. There are always better solutions and better ideas out there and we should not resist them. Instead of resisting the change and new wave I personally adopt it. Here is a similar example, as I personally progress to the master level of performance tuning, I face that it is getting harder to come up with optimal solutions. In such scenarios I rely on various tools to teach me how I can do things better. Once I learn about tools, I am often able to come up with better solutions when I face the similar situation next time. A few days ago I had received a query where the user wanted to tune it further to get the maximum out of the performance. I have re-written the similar query with the help of AdventureWorks sample database. SELECT * FROM HumanResources.Employee e INNER JOIN HumanResources.EmployeeDepartmentHistory edh ON e.BusinessEntityID = edh.BusinessEntityID INNER JOIN HumanResources.Shift s ON edh.ShiftID = s.ShiftID; User had similar query to above query was used in very critical report and wanted to get best out of the query. When I looked at the query – here were my initial thoughts Use only column in the select statements as much as you want in the application Let us look at the query pattern and data workload and find out the optimal index for it Before I give further solutions I was told by the user that they need all the columns from all the tables and creating index was not allowed in their system. He can only re-write queries or use hints to further tune this query. Now I was in the constraint box – I believe * was not a great idea but if they wanted all the columns, I believe we can’t do much besides using *. Additionally, if I cannot create a further index, I must come up with some creative way to write this query. I personally do not like to use hints in my application but there are cases when hints work out magically and gives optimal solutions. Finally, I decided to use Embarcadero’s DB Optimizer. It is a fantastic tool and very helpful when it is about performance tuning. I have previously explained how it works over here. First open DBOptimizer and open Tuning Job from File >> New >> Tuning Job. Once you open DBOptimizer Tuning Job follow the various steps indicates in the following diagram. Essentially we will take our original script and will paste that into Step 1: New SQL Text and right after that we will enable Step 2 for Generating Various cases, Step 3 for Detailed Analysis and Step 4 for Executing each generated case. Finally we will click on Analysis in Step 5 which will generate the report detailed analysis in the result pan. The detailed pan looks like. It generates various cases of T-SQL based on the original query. It applies various hints and available hints to the query and generate various execution plans of the query and displays them in the resultant. You can clearly notice that original query had a cost of 0.0841 and logical reads about 607 pages. Whereas various options which are just following it has different execution cost as well logical read. There are few cases where we have higher logical read and there are few cases where as we have very low logical read. If we pay attention the very next row to original query have Merge_Join_Query in description and have lowest execution cost value of 0.044 and have lowest Logical Reads of 29. This row contains the query which is the most optimal re-write of the original query. Let us double click over it. Here is the query: SELECT * FROM HumanResources.Employee e INNER JOIN HumanResources.EmployeeDepartmentHistory edh ON e.BusinessEntityID = edh.BusinessEntityID INNER JOIN HumanResources.Shift s ON edh.ShiftID = s.ShiftID OPTION (MERGE JOIN) If you notice above query have additional hint of Merge Join. With the help of this Merge Join query hint this query is now performing much better than before. The entire process takes less than 60 seconds. Please note that it the join hint Merge Join was optimal for this query but it is not necessary that the same hint will be helpful in all the queries. Additionally, if the workload or data pattern changes the query hint of merge join may be no more optimal join. In that case, we will have to redo the entire exercise once again. This is the reason I do not like to use hints in my queries and I discourage all of my users to use the same. However, if you look at this example, this is a great case where hints are optimizing the performance of the query. It is humanly not possible to test out various query hints and index options with the query to figure out which is the most optimal solution. Sometimes, we need to depend on the efficiency tools like DB Optimizer to guide us the way and select the best option from the suggestion provided. Let me know what you think of this article as well your experience with DB Optimizer. Please leave a comment. Reference: Pinal Dave (http://blog.sqlauthority.com) Filed under: PostADay, SQL, SQL Authority, SQL Joins, SQL Optimization, SQL Performance, SQL Query, SQL Server, SQL Tips and Tricks, T SQL, Technology

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  • How to fix Firefox Blue Screen of Death?

    - by WilliamKF
    I am running Windows XP SP3 and Firefox v3.6.2 and have an issue with Firefox causing the Blue Screen of Death. If I run in Windows safe mode, it does not occur, but running normally, it seems my firefox profile is going bad and results in certain web pages causing the BSOD. For example, presently, if I visit ebay.com, it gets BSOD. Before it was happening on google.com, but IT removed my Firefox profile and that seemed to fix the Google failure. However, now it has started occurring on ebay. I turned off all extensions and it still occurs. I'd like to fix my system so this does not occur. The IT folks don't seem to be able to solve this, so I am trying to fix it on my own. The BSOD is about something like (from memory) IRQL_NOT_LESS_THAN_OR_EQUAL. Why would safe mode avoid the issue and what does that tell us about the probable cause? I don't want to have to keep deleting my profile, so I'd like to find out the cause of the corruption.

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  • SQL SERVER – Identifying guest User using Policy Based Management

    - by pinaldave
    If you are following my recent blog posts, you may have noticed that I’ve been writing a lot about Guest User in SQL Server. Here are all the blog posts which I have written on this subject: SQL SERVER – Disable Guest Account – Serious Security Issue SQL SERVER – Force Removing User from Database – Fix: Error: Could not drop login ‘test’ as the user is currently logged in SQL SERVER – Detecting guest User Permissions – guest User Access Status SQL SERVER – guest User and MSDB Database – Enable guest User on MSDB Database One of the requests I received was whether we could create a policy that would prevent users unable guest user in user databases. Well, here is a quick tutorial to answer this. Let us see how quickly we can do it. Requirements Check if the guest user is disabled in all the user-created databases. Exclude master, tempdb and msdb database for guest user validation. We will create the following conditions based on the above two requirements: If the name of the user is ‘guest’ If the user has connect (@hasDBAccess) permission in the database Check in All user databases, except: master, tempDB and msdb Once we create two conditions, we will create a policy which will validate the conditions. Condition 1: Is the User Guest? Expand the Database >> Management >> Policy Management >> Conditions Right click on the Conditions, and click on “New Condition…”. First we will create a condition where we will validate if the user name is ‘guest’, and if it’s so, then we will further validate if it has DB access. Check the image for the necessary configuration for condition: Facet: User Expression: @Name = ‘guest’ Condition 2: Does the User have DBAccess? Expand the Database >> Management >> Policy Management >> Conditions Right click on Conditions and click on “New Condition…”. Now we will validate if the user has DB access. Check the image for necessary configuration for condition: Facet: User Expression: @hasDBAccess = False Condition 3: Exclude Databases Expand the Database >> Management >> Policy Management >> Conditions Write click on Conditions and click on “New Condition…” Now we will create condition where we will validate if database name is master, tempdb or msdb and if database name is any of them, we will not validate our first one condition with them. Check the image for necessary configuration for condition: Facet: Database Expression: @Name != ‘msdb’ AND @Name != ‘tempdb’ AND @Name != ‘master’ The next step will be creating a policy which will enforce these conditions. Creating a Policy Right click on Policies and click “New Policy…” Here, we justify what condition we want to validate against what the target is. Condition: Has User DBAccess Target Database: Every Database except (master, tempdb and MSDB) Target User: Every User in Target Database with name ‘guest’ Now we have options for two evaluation modes: 1) On Demand and 2) On Schedule We will select On Demand in this example; however, you can change the mode to On Schedule through the drop down menu, and select the interval of the evaluation of the policy. Evaluate the Policies We have selected OnDemand as our policy evaluation mode. We will now evaluate by means of executing Evaluate policy. Click on Evaluate and it will give the following result: The result demonstrates that one of the databases has a policy violation. Username guest is enabled in AdventureWorks database. You can disable the guest user by running the following code in AdventureWorks database. USE AdventureWorks; REVOKE CONNECT FROM guest; Once you run above query, you can already evaluate the policy again. Notice that the policy violation is fixed now. You can change the method of the evaluation policy to On Schedule and validate policy on interval. You can check the history of the policy and detect the violation. Quiz I have created three conditions to check if the guest user has database access or not. Now I want to ask you: Is it possible to do the same with 2 conditions? If yes, HOW? If no, WHY NOT? Reference: Pinal Dave (http://blog.sqlauthority.com) Filed under: Best Practices, CodeProject, PostADay, SQL, SQL Authority, SQL Query, SQL Server, SQL Tips and Tricks, SQLServer, T SQL, Technology Tagged: Policy Management

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  • Phpmyadmin location for nginx

    - by multiformeinggno
    I installed nginx and phpmyadmin. I set up a domain with these parameters to test phpmyadmin: server { listen 80; server_name domain.com; root /usr/share/phpmyadmin; index index.php; fastcgi_index index.php; location ~ \.php$ { include /etc/nginx/fastcgi.conf; fastcgi_param SCRIPT_FILENAME /usr/share/phpmyadmin$fastcgi_script_name; fastcgi_pass unix:/var/run/php5-fpm.sock; } } And everything works properly (if I visit the domain I can login to phpmyadmin). The problem is that it was just for testing phpmyadmin, now I'd like to move this to my 'default' site. But I can't figure out how to have it on /phpmyadmin. Here's the config for the 'default' nginx site (where I'd like to put this /phpmyadmin location): server { server_name blabla; access_log /var/log/nginx/$host.access.log; error_log /var/log/nginx/error.log; root /var/www/default; index index.php index.html; location / { try_files $uri $uri/ index.php; } location ~ \.php$ { include /etc/nginx/fastcgi.conf; fastcgi_pass unix:/var/run/php5-fpm.sock; } ### NginX Status location /nginx_status { stub_status on; access_log off; } ### FPM Status location ~ ^/(status|ping)$ { fastcgi_pass unix:/var/run/php5-fpm.sock; access_log off; } }

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  • Properly force SSL with .htaccess, no double authentication

    - by cwd
    I'm trying to force SSL with .htaccess on a shared host. This means there I only have access to .htaccess and not the vhosts config. I know you can put a rule in the VirtualHost config file to force SSL which will be picked up there (and acted upon first), preventing double authentication, but I can't get to that. Here's the progress I've made: Config 1 This works pretty well but it does force double authentication if you visit http://site.com - once for http and then once for https. Once you are logged in, it automatically redirects http://site.com/page1.html to the https coutnerpart just fine: RewriteEngine On RewriteCond %{HTTPS} !=on RewriteRule ^ https://%{HTTP_HOST}%{REQUEST_URI} [L,R=301] RewriteEngine on RewriteCond %{HTTP_HOST} !(^www\.site\.com*)$ RewriteRule (.*) https://www.site.com$1 [R=301,L] AuthName "Locked" AuthUserFile "/home/.htpasswd" AuthType Basic require valid-user Config 2 If I add this to the top of the file, it works a lot better in that it will switch to SSL before prompting for the password: SSLOptions +StrictRequire SSLRequireSSL SSLRequire %{HTTP_HOST} eq "site.com" ErrorDocument 403 https://site.com It's clever how it will use the SSLRequireSSL option and the ErrorDocument403 to redirect to the secure version of the site. My only complaint is that if you try and access http://site.com/page1.html it will redirect to https://site.com/ So it is forcing SSL without a double-login, but it is not properly forwarding non-SSL resources to their SSL counterparts. Regarding the first config, Insyte mentioned "using mod_rewrite to perform a simple redirect is a bit of overkill. Use the Redirect directive instead. It's possible this may even fix your problem, as I believe mod_rewrite rules are some of the last directives to be processed, just before the file is actually grabbed from the filesystem" I have not had no such luck on finding a force-ssl config option with the redirect directive and so have been unable to test this theory.

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  • How to automatically remove Flash history/privacy trail? Or stop Flash from storing it?

    - by Arjan van Bentem
    Many people have heard about third-party cookies, and some browsers even block those by default. Some people may even be using Private Browsing modes. However, only few seem to realise that Adobe's Flash player also leaves a cross-browser trail on your local hard drive, and allows for sending cookie-like information back to the server, including third-party sites. And because it is a plugin, Flash does not take any of the browser's privacy settings into account. Sorry for the long post, but first some details about why using Flash raises a privacy concern, followed by the results of my tests: The Flash player keeps a cross-browser history of the domain names of the Flash-sites your computer has visited. Unlike your browser's history, this history is not limited to a certain number of days. History is also recorded while using so-called Private Browsing modes. It is stored on your hard drive (though, as described below, without going to Adobe's site you won't know what is stored). I am not sure if any date and time information is kept about each visit, but to see the domain names: right-click on some Flash content, open the settings dialog, and click the Help icon or click the Advanced button within the Privacy tab. This opens a browser to the help pages on Adobe.com, where one can click through to the Website Storage Settings panel. One can clear the existing list, but one cannot stop it from being recorded again. Flash allows for storing data on your local hard drive, using so-called Local Shared Objects (aka "Flash Cookies"). Just like HTTP cookies, this data can be sent back to the server, for tracking purposes. They are cross-browser, have no expiration date, and no user defined maximum lifetime can be set in the Flash preferences either. These not being HTTP cookies, they are (of course) not blocked by a browser's cookies preferences and are not removed when the normal HTTP cookies are deleted. Adobe has announced that version 10.1 will obey Private Browsing in most popular browsers, but unfortunately no word about also removing the data whenever normal cookies are deleted manually. And its implementation might be confusing: [..] if the browser is in normal browsing mode when the Flash Player instance is created, then that particular instance will forever be in normal browsing mode (private browsing is turned off). Accordingly, toggling private browsing on or off without refreshing the page or closing the private browsing window will not impact Flash Player. Local Shared Objects are not limited to the site you visit, and third-party storage is enabled by default. At the Global Storage Settings panel one can deselect the default Allow third-party Flash content to store data on your computer. Because of the cross-browser and expiration-less nature (and the fact that few people know about it), I feel that the cross-browser third-party Flash Cookies are more dangerous for visitor tracking than third-party normal HTTP cookies. They are even used to restore plain HTTP cookies that the user tried to delete: "All advertisers, websites and networks use cookies for targeted advertising, but cookies are under attack. According to current research they are being erased by 40% of users creating serious problems," says Mookie Tenembaum, founder of United Virtualities. "From simple frequency capping to the more sophisticated behavioral targeting, cookies are an essential part of any online ad campaign. PIE ["Persistent Identification Element"] will give publishers and third-party providers a persistent backup to cookies effectively rendering them unassailable", adds Tenembaum. [..] To justify this tracking mechanism, UV's Tenembaum said, "The user is not proficient enough in technology to know if the cookie is good or bad, or how it works." When selecting None (zero KB) for Specify the amount of disk space that website websites that you haven't yet visited can use to store information on your computer, and checking Never ask again then some sites do not work. However, the same site might work when setting it to None but without selecting Never ask again, and then choose Deny whenever prompted. Both options would result in zero KB of data being allowed, but the behaviour differs. The plugin also provides a Flash Player cache for Adobe-signed files. I guess these files are not an issue. So: how to automatically delete that information? On a Mac, one can find a settings.sol file and a folder for each visited Flash-website in: $HOME/Library/Preferences/Macromedia/Flash Player/macromedia.com/support/flashplayer/sys/ Deleting the settings.sol file and all the folders in sys, removes the trail from the settings panels. However, the actual Local Shared Ojects are elsewhere (see Wikipedia for locations on other operating systems), in a randomly named subfolder of: $HOME/Library/Preferences/Macromedia/Flash Player/#SharedObjects But then: how to remove this automatically? Simply removing the folders and the settings.sol file every now and then (like by using launchd or Windows' Task Scheduler) may interfere with active browsers. Or is it safe to assume that, given the cross-browser nature, the plugin would not care if things are removed while it is active? Only clearing during log-off may not work for those who hibernate all the time. Firefox users can install BetterPrivacy or Objection to delete the Local Shared Objects (for all others browsers as well). I don't know if that also deletes the trail of website domain names. Or: how to stop Flash from storing a history trail? Change of plans: I'm currently testing prohibiting Flash to write to its own sys and #SharedObjects folders. So far, Flash has not tried to restore permissions (though, when deleting the folders, Flash will of course recreate them). I've not encountered any problems but this may take some while to validate, using multiple browsers and sites. I've not yet found a log that reports errors. On a Mac: cd "$HOME/Library/Preferences/Macromedia/Flash Player/macromedia.com/support/flashplayer" rm -r sys/* chmod u-w sys cd "$HOME/Library/Preferences/Macromedia/Flash Player" # preserve the randomly named subfolders (only preserving the latest would suffice; see below) rm -r \#SharedObjects/*/* chmod -R u-w \#SharedObjects I guess the above chmods cannot be achieved on an old Windows system (I'm not sure about XP and Vista?). Though maybe on Windows one could replace the folders sys and #SharedObjects with dummy files with the same names? Anyone? Obviously, keeping Flash from storing those Local Shared Objects for all sites may cause problems. Some test results (Flash 10 on Mac OS X): When blocking the sys folder (even when leaving the #SharedObjects folder writable) then YouTube won't remember your volume settings while viewing multiple videos. Temporarily allowing write access to the blocked folders while visiting trusted sites (to only create folders for domains you like, maybe including references in settings.sol) solves that. This way, for YouTube, Flash could be allowed to write to sys/#s.ytimg.com and #SharedObjects/s.ytimg.com, while Flash could not create new folders for other domains. One may also need to make settings.sol read-only afterwards, or delete it again. When blocking both the sys and #SharedObjects folders, YouTube and Vimeo work fine (though they might not remember any settings). However, Bits on the Run refuses to even show the video player. This is solved by temporarily unblocking the #SharedObjects folder, to allow Flash to create a subfolder with some random name. Within this folder, it would create yet another folder for the current Flash website (content.bitsontherun.com). Removing that website-specific folder, and blocking both #SharedObjects and the randomly named subfolder, still seems to allow Bits on the Run to operate, even though it still cannot write anything to disk. So: the existence of the randomly named subfolder (even when write protected) is important for some sites. When I first found the #SharedObjects folder, it held many subfolders with random names, some created on the very same day. I wonder when Flash decides it wants a new folder, and how it determines (and remembers) that random name. For a moment I considered not blocking write access for sys and #SharedObjects, but explicitly creating read-only folders for well-known third-party tracking domains (like based on a list from, for example, AdBlock Plus). That way, any other domain could still create Local Shared Objects. But the list would be long, and the domains from AdBlock Plus are probably all third-party domains anyway, so disabling Allow third-party Flash content to store data on your computer might have the very same result. Any experience anyone? (Final notes: if the above links to the settings panels do not work in the future, then use the URL that is known to Flash player as a starting point: www.adobe.com/go/settingsmanager. See also "You Deleted Your Cookies? Think Again" at Wired.com -- which uses Flash cookies itself as well... For the very suspicious using Time Machine: you may want to exclude both folders, for each user, and remove the trace that is already on your backup.)

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  • SQL SERVER – Parsing SSIS Catalog Messages – Notes from the Field #030

    - by Pinal Dave
    [Note from Pinal]: This is a new episode of Notes from the Field series. SQL Server Integration Service (SSIS) is one of the most key essential part of the entire Business Intelligence (BI) story. It is a platform for data integration and workflow applications. The tool may also be used to automate maintenance of SQL Server databases and updates to multidimensional cube data. In this episode of the Notes from the Field series I requested SSIS Expert Andy Leonard to discuss one of the most interesting concepts of SSIS Catalog Messages. There are plenty of interesting and useful information captured in the SSIS catalog and we will learn together how to explore the same. The SSIS Catalog captures a lot of cool information by default. Here’s a query I use to parse messages from the catalog.operation_messages table in the SSISDB database, where the logged messages are stored. This query is set up to parse a default message transmitted by the Lookup Transformation. It’s one of my favorite messages in the SSIS log because it gives me excellent information when I’m tuning SSIS data flows. The message reads similar to: Data Flow Task:Information: The Lookup processed 4485 rows in the cache. The processing time was 0.015 seconds. The cache used 1376895 bytes of memory. The query: USE SSISDB GO DECLARE @MessageSourceType INT = 60 DECLARE @StartOfIDString VARCHAR(100) = 'The Lookup processed ' DECLARE @ProcessingTimeString VARCHAR(100) = 'The processing time was ' DECLARE @CacheUsedString VARCHAR(100) = 'The cache used ' DECLARE @StartOfIDSearchString VARCHAR(100) = '%' + @StartOfIDString + '%' DECLARE @ProcessingTimeSearchString VARCHAR(100) = '%' + @ProcessingTimeString + '%' DECLARE @CacheUsedSearchString VARCHAR(100) = '%' + @CacheUsedString + '%' SELECT operation_id , SUBSTRING(MESSAGE, (PATINDEX(@StartOfIDSearchString,MESSAGE) + LEN(@StartOfIDString) + 1), ((CHARINDEX(' ', MESSAGE, PATINDEX(@StartOfIDSearchString,MESSAGE) + LEN(@StartOfIDString) + 1)) - (PATINDEX(@StartOfIDSearchString, MESSAGE) + LEN(@StartOfIDString) + 1))) AS LookupRowsCount , SUBSTRING(MESSAGE, (PATINDEX(@ProcessingTimeSearchString,MESSAGE) + LEN(@ProcessingTimeString) + 1), ((CHARINDEX(' ', MESSAGE, PATINDEX(@ProcessingTimeSearchString,MESSAGE) + LEN(@ProcessingTimeString) + 1)) - (PATINDEX(@ProcessingTimeSearchString, MESSAGE) + LEN(@ProcessingTimeString) + 1))) AS LookupProcessingTime , CASE WHEN (CONVERT(numeric(3,3),SUBSTRING(MESSAGE, (PATINDEX(@ProcessingTimeSearchString,MESSAGE) + LEN(@ProcessingTimeString) + 1), ((CHARINDEX(' ', MESSAGE, PATINDEX(@ProcessingTimeSearchString,MESSAGE) + LEN(@ProcessingTimeString) + 1)) - (PATINDEX(@ProcessingTimeSearchString, MESSAGE) + LEN(@ProcessingTimeString) + 1))))) = 0 THEN 0 ELSE CONVERT(bigint,SUBSTRING(MESSAGE, (PATINDEX(@StartOfIDSearchString,MESSAGE) + LEN(@StartOfIDString) + 1), ((CHARINDEX(' ', MESSAGE, PATINDEX(@StartOfIDSearchString,MESSAGE) + LEN(@StartOfIDString) + 1)) - (PATINDEX(@StartOfIDSearchString, MESSAGE) + LEN(@StartOfIDString) + 1)))) / CONVERT(numeric(3,3),SUBSTRING(MESSAGE, (PATINDEX(@ProcessingTimeSearchString,MESSAGE) + LEN(@ProcessingTimeString) + 1), ((CHARINDEX(' ', MESSAGE, PATINDEX(@ProcessingTimeSearchString,MESSAGE) + LEN(@ProcessingTimeString) + 1)) - (PATINDEX(@ProcessingTimeSearchString, MESSAGE) + LEN(@ProcessingTimeString) + 1)))) END AS LookupRowsPerSecond , SUBSTRING(MESSAGE, (PATINDEX(@CacheUsedSearchString,MESSAGE) + LEN(@CacheUsedString) + 1), ((CHARINDEX(' ', MESSAGE, PATINDEX(@CacheUsedSearchString,MESSAGE) + LEN(@CacheUsedString) + 1)) - (PATINDEX(@CacheUsedSearchString, MESSAGE) + LEN(@CacheUsedString) + 1))) AS LookupBytesUsed ,CASE WHEN (CONVERT(bigint,SUBSTRING(MESSAGE, (PATINDEX(@StartOfIDSearchString,MESSAGE) + LEN(@StartOfIDString) + 1), ((CHARINDEX(' ', MESSAGE, PATINDEX(@StartOfIDSearchString,MESSAGE) + LEN(@StartOfIDString) + 1)) - (PATINDEX(@StartOfIDSearchString, MESSAGE) + LEN(@StartOfIDString) + 1)))))= 0 THEN 0 ELSE CONVERT(bigint,SUBSTRING(MESSAGE, (PATINDEX(@CacheUsedSearchString,MESSAGE) + LEN(@CacheUsedString) + 1), ((CHARINDEX(' ', MESSAGE, PATINDEX(@CacheUsedSearchString,MESSAGE) + LEN(@CacheUsedString) + 1)) - (PATINDEX(@CacheUsedSearchString, MESSAGE) + LEN(@CacheUsedString) + 1)))) / CONVERT(bigint,SUBSTRING(MESSAGE, (PATINDEX(@StartOfIDSearchString,MESSAGE) + LEN(@StartOfIDString) + 1), ((CHARINDEX(' ', MESSAGE, PATINDEX(@StartOfIDSearchString,MESSAGE) + LEN(@StartOfIDString) + 1)) - (PATINDEX(@StartOfIDSearchString, MESSAGE) + LEN(@StartOfIDString) + 1)))) END AS LookupBytesPerRow FROM [catalog].[operation_messages] WHERE message_source_type = @MessageSourceType AND MESSAGE LIKE @StartOfIDSearchString GO Note that you have to set some parameter values: @MessageSourceType [int] – represents the message source type value from the following results: Value     Description 10           Entry APIs, such as T-SQL and CLR Stored procedures 20           External process used to run package (ISServerExec.exe) 30           Package-level objects 40           Control Flow tasks 50           Control Flow containers 60           Data Flow task 70           Custom execution message Note: Taken from Reza Rad’s (excellent!) helper.MessageSourceType table found here. @StartOfIDString [VarChar(100)] – use this to uniquely identify the message field value you wish to parse. In this case, the string ‘The Lookup processed ‘ identifies all the Lookup Transformation messages I desire to parse. @ProcessingTimeString [VarChar(100)] – this parameter is message-specific. I use this parameter to specifically search the message field value for the beginning of the Lookup Processing Time value. For this execution, I use the string ‘The processing time was ‘. @CacheUsedString [VarChar(100)] – this parameter is also message-specific. I use this parameter to specifically search the message field value for the beginning of the Lookup Cache  Used value. It returns the memory used, in bytes. For this execution, I use the string ‘The cache used ‘. The other parameters are built from variations of the parameters listed above. The query parses the values into text. The string values are converted to numeric values for ratio calculations; LookupRowsPerSecond and LookupBytesPerRow. Since ratios involve division, CASE statements check for denominators that equal 0. Here are the results in an SSMS grid: This is not the only way to retrieve this information. And much of the code lends itself to conversion to functions. If there is interest, I will share the functions in an upcoming post. If you want to get started with SSIS with the help of experts, read more over at Fix Your SQL Server. Reference: Pinal Dave (http://blog.sqlauthority.com)Filed under: Notes from the Field, PostADay, SQL, SQL Authority, SQL Backup and Restore, SQL Query, SQL Server, SQL Tips and Tricks, T SQL Tagged: SSIS

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  • Developer Training – Difficult Questions and Alternative Perspective – Part 3

    - by pinaldave
    Developer Training - Importance and Significance - Part 1 Developer Training – Employee Morals and Ethics – Part 2 Developer Training – Difficult Questions and Alternative Perspective - Part 3 Developer Training – Various Options for Developer Training – Part 4 Developer Training – A Conclusive Summary- Part 5 Congratulations!  You are now a fully trained developer!  You spent hours in a classroom, watching webinars, and reading materials.  You are now more educated and more prepared than ever before.  Now what? Stay or Quit The simple answer is that you now have two options – stay where you are or move on to a new job.  Even though you might now be smarter than you have ever felt before, this can still be a tough decision to make.  You feel extra trained and ready for a promotion or a raise, but you and your employer might not see eye to eye on this issue.  The logical conclusion is to go on a job hunt, but that might not be the most ethical thing to do. Click Image to Enlarge Manager’s Perspective Click Image to Enlarge Try to see the issue from your manager’s perspective.  You feel that you have just spent a lot of time and energy getting trained, and you should be rewarded.  But they have invested their time and energy in you.  They might see the training as a way to help you complete the goals they require from you, or as a way to help you complete tasks that will ultimately end in a reward or promotion. Moral Compass As in most cases, honesty is the best policy.  Be open with your manager about your expectations, and ask them to explain their goals.  When there is open and honest communication, everyone can walk away happy.  If you’re unable to discuss with your manager for one reason or another, just try to keep the company policy in mind and follow your own moral compass.  If all else fails, and your company is unwilling to make allowances for your new value, offer to pay the company back for the training before moving on your way. Whether you stay at your old job or move on to a new one, you are still faced with the question of what you’re going to do with all your new knowledge.  If you feel comfortable, offer to train others around you who are interested in the same subject.  This can look very good on your resume, and if you are working in a team environment it is sure to help you in the long run! What Next? You can even offer to train other trainers at the company – managers, those above you, or even report back to your original trainer about how your education is helping you in the work place.  Obviously this should be completely voluntary on the trainer’s part.  Taking advice from a “newbie” may not be their favorite idea, but it could also show the company that you are open to expanding your horizons and being helpful to everyone around you. Last in Line for Opportunity Click Image to Enlarge At this time, let us address a subject related to training and what to do with it – what if you are always overlooked for training?  This can as thorny a problem as receiving training in the first place.  The best advice is to let your supervisors know that you are always open to training and very interested in certain topics.  If you are consistently passed over, be patient.  Your turn will probably come, but the company as a whole has to focus on other problems at the moment.  If you feel that there are more personal issues at play, be sure to bring this up with your supervisor in a calm and professional manager so that everything can be worked out best for both parties. You, Yourself and Your Future! If all else fails, offer to pay for training yourself.  Perhaps money problems are at the root of being passed over.  Even if there are other reasons, offering to pay your own way shows your dedication and could work out well for you in the long run.  Always remember – in life you have to go out and make your own way, you cannot always sit and wait for things to land in your lap. Reference: Pinal Dave (http://blog.sqlauthority.com) Filed under: Developer Training, PostADay, SQL, SQL Authority, SQL Query, SQL Server, SQL Tips and Tricks, T SQL, Technology

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  • Big Data – What is Big Data – 3 Vs of Big Data – Volume, Velocity and Variety – Day 2 of 21

    - by Pinal Dave
    Data is forever. Think about it – it is indeed true. Are you using any application as it is which was built 10 years ago? Are you using any piece of hardware which was built 10 years ago? The answer is most certainly No. However, if I ask you – are you using any data which were captured 50 years ago, the answer is most certainly Yes. For example, look at the history of our nation. I am from India and we have documented history which goes back as over 1000s of year. Well, just look at our birthday data – atleast we are using it till today. Data never gets old and it is going to stay there forever.  Application which interprets and analysis data got changed but the data remained in its purest format in most cases. As organizations have grown the data associated with them also grew exponentially and today there are lots of complexity to their data. Most of the big organizations have data in multiple applications and in different formats. The data is also spread out so much that it is hard to categorize with a single algorithm or logic. The mobile revolution which we are experimenting right now has completely changed how we capture the data and build intelligent systems.  Big organizations are indeed facing challenges to keep all the data on a platform which give them a  single consistent view of their data. This unique challenge to make sense of all the data coming in from different sources and deriving the useful actionable information out of is the revolution Big Data world is facing. Defining Big Data The 3Vs that define Big Data are Variety, Velocity and Volume. Volume We currently see the exponential growth in the data storage as the data is now more than text data. We can find data in the format of videos, musics and large images on our social media channels. It is very common to have Terabytes and Petabytes of the storage system for enterprises. As the database grows the applications and architecture built to support the data needs to be reevaluated quite often. Sometimes the same data is re-evaluated with multiple angles and even though the original data is the same the new found intelligence creates explosion of the data. The big volume indeed represents Big Data. Velocity The data growth and social media explosion have changed how we look at the data. There was a time when we used to believe that data of yesterday is recent. The matter of the fact newspapers is still following that logic. However, news channels and radios have changed how fast we receive the news. Today, people reply on social media to update them with the latest happening. On social media sometimes a few seconds old messages (a tweet, status updates etc.) is not something interests users. They often discard old messages and pay attention to recent updates. The data movement is now almost real time and the update window has reduced to fractions of the seconds. This high velocity data represent Big Data. Variety Data can be stored in multiple format. For example database, excel, csv, access or for the matter of the fact, it can be stored in a simple text file. Sometimes the data is not even in the traditional format as we assume, it may be in the form of video, SMS, pdf or something we might have not thought about it. It is the need of the organization to arrange it and make it meaningful. It will be easy to do so if we have data in the same format, however it is not the case most of the time. The real world have data in many different formats and that is the challenge we need to overcome with the Big Data. This variety of the data represent  represent Big Data. Big Data in Simple Words Big Data is not just about lots of data, it is actually a concept providing an opportunity to find new insight into your existing data as well guidelines to capture and analysis your future data. It makes any business more agile and robust so it can adapt and overcome business challenges. Tomorrow In tomorrow’s blog post we will try to answer discuss Evolution of Big Data. Reference: Pinal Dave (http://blog.sqlauthority.com) Filed under: Big Data, PostADay, SQL, SQL Authority, SQL Query, SQL Server, SQL Tips and Tricks, T SQL

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  • How do I find out the Mac Address Firefox submits for Geolocation?

    - by Jim McKeeth
    I moved, but have the same router and cable box. Now when I visit Google Maps it still shows my old location. I went to the SkyhookWireless update page to update my Mac Address with my new location. The process is you put in your Mac address and it shows you the current location, and then you adjust that location and submit it. When I got the Mac Address from the status page on my router Skyhook reported that location as in Pakistan, which isn't even the correct continent (as my old or new address). I tried every other Mac address I could come up with: The cable router, the Wireless router's other Mac address, my PC's Mac address, etc. and none of them reported any location on the Skyhook page. So I am guessing that there is another Mac address, or some other bit of information that is used by Firefox when it reports to Google Maps my current location. Now that you have the back story, how do I find the Mac address or whatever information it is that Firefox (or other browsers) use to determine my Geolocation? Everything I have read online is rather vague. The next option I am considering is hooking a logging proxy onto Firefox and seeing what data it sends, but I'd rather find an easier method. Related: How do I update the geo location of my house?

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  • SQL SERVER – CXPACKET – Parallelism – Usual Solution – Wait Type – Day 6 of 28

    - by pinaldave
    CXPACKET has to be most popular one of all wait stats. I have commonly seen this wait stat as one of the top 5 wait stats in most of the systems with more than one CPU. Books On-Line: Occurs when trying to synchronize the query processor exchange iterator. You may consider lowering the degree of parallelism if contention on this wait type becomes a problem. CXPACKET Explanation: When a parallel operation is created for SQL Query, there are multiple threads for a single query. Each query deals with a different set of the data (or rows). Due to some reasons, one or more of the threads lag behind, creating the CXPACKET Wait Stat. There is an organizer/coordinator thread (thread 0), which takes waits for all the threads to complete and gathers result together to present on the client’s side. The organizer thread has to wait for the all the threads to finish before it can move ahead. The Wait by this organizer thread for slow threads to complete is called CXPACKET wait. Note that not all the CXPACKET wait types are bad. You might experience a case when it totally makes sense. There might also be cases when this is unavoidable. If you remove this particular wait type for any query, then that query may run slower because the parallel operations are disabled for the query. Reducing CXPACKET wait: We cannot discuss about reducing the CXPACKET wait without talking about the server workload type. OLTP: On Pure OLTP system, where the transactions are smaller and queries are not long but very quick usually, set the “Maximum Degree of Parallelism” to 1 (one). This way it makes sure that the query never goes for parallelism and does not incur more engine overhead. EXEC sys.sp_configure N'cost threshold for parallelism', N'1' GO RECONFIGURE WITH OVERRIDE GO Data-warehousing / Reporting server: As queries will be running for long time, it is advised to set the “Maximum Degree of Parallelism” to 0 (zero). This way most of the queries will utilize the parallel processor, and long running queries get a boost in their performance due to multiple processors. EXEC sys.sp_configure N'cost threshold for parallelism', N'0' GO RECONFIGURE WITH OVERRIDE GO Mixed System (OLTP & OLAP): Here is the challenge. The right balance has to be found. I have taken a very simple approach. I set the “Maximum Degree of Parallelism” to 2, which means the query still uses parallelism but only on 2 CPUs. However, I keep the “Cost Threshold for Parallelism” very high. This way, not all the queries will qualify for parallelism but only the query with higher cost will go for parallelism. I have found this to work best for a system that has OLTP queries and also where the reporting server is set up. Here, I am setting ‘Cost Threshold for Parallelism’ to 25 values (which is just for illustration); you can choose any value, and you can find it out by experimenting with the system only. In the following script, I am setting the ‘Max Degree of Parallelism’ to 2, which indicates that the query that will have a higher cost (here, more than 25) will qualify for parallel query to run on 2 CPUs. This implies that regardless of the number of CPUs, the query will select any two CPUs to execute itself. EXEC sys.sp_configure N'cost threshold for parallelism', N'25' GO EXEC sys.sp_configure N'max degree of parallelism', N'2' GO RECONFIGURE WITH OVERRIDE GO Read all the post in the Wait Types and Queue series. Additionally a must read comment of Jonathan Kehayias. Note: The information presented here is from my experience and I no way claim it to be accurate. I suggest you all to read the online book for further clarification. All the discussion of Wait Stats over here is generic and it varies from system to system. It is recommended that you test this on the development server before implementing on the production server. Reference: Pinal Dave (http://blog.SQLAuthority.com) Filed under: DMV, Pinal Dave, PostADay, SQL, SQL Authority, SQL Query, SQL Scripts, SQL Server, SQL Tips and Tricks, SQL Wait Stats, SQL Wait Types, T SQL, Technology

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  • SQL SERVER – Fundamentals of Columnstore Index

    - by pinaldave
    There are two kind of storage in database. Row Store and Column Store. Row store does exactly as the name suggests – stores rows of data on a page – and column store stores all the data in a column on the same page. These columns are much easier to search – instead of a query searching all the data in an entire row whether the data is relevant or not, column store queries need only to search much lesser number of the columns. This means major increases in search speed and hard drive use. Additionally, the column store indexes are heavily compressed, which translates to even greater memory and faster searches. I am sure this looks very exciting and it does not mean that you convert every single index from row store to column store index. One has to understand the proper places where to use row store or column store indexes. Let us understand in this article what is the difference in Columnstore type of index. Column store indexes are run by Microsoft’s VertiPaq technology. However, all you really need to know is that this method of storing data is columns on a single page is much faster and more efficient. Creating a column store index is very easy, and you don’t have to learn new syntax to create them. You just need to specify the keyword “COLUMNSTORE” and enter the data as you normally would. Keep in mind that once you add a column store to a table, though, you cannot delete, insert or update the data – it is READ ONLY. However, since column store will be mainly used for data warehousing, this should not be a big problem. You can always use partitioning to avoid rebuilding the index. A columnstore index stores each column in a separate set of disk pages, rather than storing multiple rows per page as data traditionally has been stored. The difference between column store and row store approaches is illustrated below: In case of the row store indexes multiple pages will contain multiple rows of the columns spanning across multiple pages. In case of column store indexes multiple pages will contain multiple single columns. This will lead only the columns needed to solve a query will be fetched from disk. Additionally there is good chance that there will be redundant data in a single column which will further help to compress the data, this will have positive effect on buffer hit rate as most of the data will be in memory and due to same it will not need to be retrieved. Let us see small example of how columnstore index improves the performance of the query on a large table. As a first step let us create databaseset which is large enough to show performance impact of columnstore index. The time taken to create sample database may vary on different computer based on the resources. USE AdventureWorks GO -- Create New Table CREATE TABLE [dbo].[MySalesOrderDetail]( [SalesOrderID] [int] NOT NULL, [SalesOrderDetailID] [int] NOT NULL, [CarrierTrackingNumber] [nvarchar](25) NULL, [OrderQty] [smallint] NOT NULL, [ProductID] [int] NOT NULL, [SpecialOfferID] [int] NOT NULL, [UnitPrice] [money] NOT NULL, [UnitPriceDiscount] [money] NOT NULL, [LineTotal] [numeric](38, 6) NOT NULL, [rowguid] [uniqueidentifier] NOT NULL, [ModifiedDate] [datetime] NOT NULL ) ON [PRIMARY] GO -- Create clustered index CREATE CLUSTERED INDEX [CL_MySalesOrderDetail] ON [dbo].[MySalesOrderDetail] ( [SalesOrderDetailID]) GO -- Create Sample Data Table -- WARNING: This Query may run upto 2-10 minutes based on your systems resources INSERT INTO [dbo].[MySalesOrderDetail] SELECT S1.* FROM Sales.SalesOrderDetail S1 GO 100 Now let us do quick performance test. I have kept STATISTICS IO ON for measuring how much IO following queries take. In my test first I will run query which will use regular index. We will note the IO usage of the query. After that we will create columnstore index and will measure the IO of the same. -- Performance Test -- Comparing Regular Index with ColumnStore Index USE AdventureWorks GO SET STATISTICS IO ON GO -- Select Table with regular Index SELECT ProductID, SUM(UnitPrice) SumUnitPrice, AVG(UnitPrice) AvgUnitPrice, SUM(OrderQty) SumOrderQty, AVG(OrderQty) AvgOrderQty FROM [dbo].[MySalesOrderDetail] GROUP BY ProductID ORDER BY ProductID GO -- Table 'MySalesOrderDetail'. Scan count 1, logical reads 342261, physical reads 0, read-ahead reads 0. -- Create ColumnStore Index CREATE NONCLUSTERED COLUMNSTORE INDEX [IX_MySalesOrderDetail_ColumnStore] ON [MySalesOrderDetail] (UnitPrice, OrderQty, ProductID) GO -- Select Table with Columnstore Index SELECT ProductID, SUM(UnitPrice) SumUnitPrice, AVG(UnitPrice) AvgUnitPrice, SUM(OrderQty) SumOrderQty, AVG(OrderQty) AvgOrderQty FROM [dbo].[MySalesOrderDetail] GROUP BY ProductID ORDER BY ProductID GO It is very clear from the results that query is performance extremely fast after creating ColumnStore Index. The amount of the pages it has to read to run query is drastically reduced as the column which are needed in the query are stored in the same page and query does not have to go through every single page to read those columns. If we enable execution plan and compare we can see that column store index performance way better than regular index in this case. Let us clean up the database. -- Cleanup DROP INDEX [IX_MySalesOrderDetail_ColumnStore] ON [dbo].[MySalesOrderDetail] GO TRUNCATE TABLE dbo.MySalesOrderDetail GO DROP TABLE dbo.MySalesOrderDetail GO In future posts we will see cases where Columnstore index is not appropriate solution as well few other tricks and tips of the columnstore index. Reference: Pinal Dave (http://blog.SQLAuthority.com) Filed under: Pinal Dave, PostADay, SQL, SQL Authority, SQL Index, SQL Optimization, SQL Performance, SQL Query, SQL Scripts, SQL Server, SQL Tips and Tricks, T SQL, Technology

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  • SQL SERVER – An Efficiency Tool to Compare and Synchronize SQL Server Databases

    - by Pinal Dave
    There is no need to reinvent the wheel if it is already invented and if the wheel is already available at ease, there is no need to wait to grab it. Here is the similar situation. I came across a very interesting situation and I had to look for an efficient tool which can make my life easier and solve my business problem. Here is the scenario. One of the developers had deleted few rows from the very important mapping table of our development server (thankfully, it was not the production server). Though it was a development server, the entire development team had to stop working as the application started to crash on every page. Think about the lost of manpower and efficiency which we started to loose.  Pretty much every department had to stop working as our internal development application stopped working. Thankfully, we even take a backup of our development server and we had access to full backup of the entire database at 6 AM morning. We do not take as a frequent backup of development server as production server (naturally!). Even though we had a full backup, the solution was not to restore the database. Think about it, there were plenty of the other operations since the last good full backup and if we restore a full backup, we will pretty much overwrite on the top of the work done by developers since morning. Now, as restoring the full backup was not an option we decided to restore the same database on another server. Once we had restored our database to another server, the challenge was to compare the table from where the database was deleted. The mapping table from where the data were deleted contained over 5000 rows and it was humanly impossible to compare both the tables manually. Finally we decided to use efficiency tool dbForge Data Compare for SQL Server from DevArt. dbForge Data Compare for SQL Server is a powerful, fast and easy to use SQL compare tool, capable of using native SQL Server backups as metadata source. (FYI we Downloaded dbForge Data Compare) Once we discovered the product, we immediately downloaded the product and installed on our development server. After we installed the product, we were greeted with the following screen. We clicked on the New Data Comparision to start our new comparison project. It brought up following screen. Here is the best part of the product, we just had to enter our database connection username and password along with source and destination details and we are done. The entire process is very simple and self intuiting. The best part was that for the source, we can either select database or even backup. This was indeed fantastic feature. Think about this, if you have a very big database, it will take long time to restore on the server. Once it is restored, you will be able to work with it. However, when you are working with dbForge Data Compare it will accept database backup as your source or destination. Once I click on the execute it brought up following screen where it displayed an excellent summary of the data compare. It has dedicated tabs for the what is changing in what table as well had details of the changed data. The best part is that, once we had reviewed the change. We click on the Synchronize button in the menu bar and it brought up following screen. You can see that the screen has very simple straight forward but very powerful features. You can generate a script to synchronize from target to source or even from source to target. Additionally, the database is a very complicated world and there are extensive options to configure various database options on the next screen. We also have the option to either generate script or directly execute the script to target server. I like to play on the safe side and I generated the script for my synchronization and later on after review I deployed the scripts on the server. Well, my team and we were able to get going from our disaster in less than 10 minutes. There were few people in our team were indeed disappointed as they were thinking of going home early that day but in less than 10 minutes they had to get back to work. There are so many other features in  dbForge Data Compare for SQL Server, I am already planning to make this product company wide recommended product for Data Compare tool. Hats off to the team who have build this product. Here are few of the features salient features of the dbForge Data Compare for SQL Server Perform SQL Server database comparison to detect changes Compare SQL Server backups with live databases Analyze data differences between two databases Synchronize two databases that went out of sync Restore data of a particular table from the backup Generate data comparison reports in Excel and HTML formats Copy look-up data from development database to production Automate routine data synchronization tasks with command-line interface Go Ahead and Download the dbForge Data Compare for SQL Server right away. It is always a good idea to get familiar with the important tools before hand instead of learning it under pressure of disaster. Reference: Pinal Dave (http://blog.sqlauthority.com) Filed under: PostADay, SQL, SQL Authority, SQL Query, SQL Server, SQL Tips and Tricks, SQL Utility, T SQL, Technology

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  • SQL SERVER – Solution – Puzzle – SELECT * vs SELECT COUNT(*)

    - by pinaldave
    Earlier I have published Puzzle Why SELECT * throws an error but SELECT COUNT(*) does not. This question have received many interesting comments. Let us go over few of the answers, which are valid. Before I start the same, let me acknowledge Rob Farley who has not only answered correctly very first but also started interesting conversation in the same thread. The usual question will be what is the right answer. I would like to point to official Microsoft Connect Items which discusses the same. RGarvao https://connect.microsoft.com/SQLServer/feedback/details/671475/select-test-where-exists-select tiberiu utan http://connect.microsoft.com/SQLServer/feedback/details/338532/count-returns-a-value-1 Rob Farley count(*) is about counting rows, not a particular column. It doesn’t even look to see what columns are available, it’ll just count the rows, which in the case of a missing FROM clause, is 1. “select *” is designed to return columns, and therefore barfs if there are none available. Even more odd is this one: select ‘blah’ where exists (select *) You might be surprised at the results… Koushik The engine performs a “Constant scan” for Count(*) where as in the case of “SELECT *” the engine is trying to perform either Index/Cluster/Table scans. amikolaj When you query ‘select * from sometable’, SQL replaces * with the current schema of that table. With out a source for the schema, SQL throws an error. so when you query ‘select count(*)’, you are counting the one row. * is just a constant to SQL here. Check out the execution plan. Like the description states – ‘Scan an internal table of constants.’ You could do ‘select COUNT(‘my name is adam and this is my answer’)’ and get the same answer. Netra Acharya SELECT * Here, * represents all columns from a table. So it always looks for a table (As we know, there should be FROM clause before specifying table name). So, it throws an error whenever this condition is not satisfied. SELECT COUNT(*) Here, COUNT is a Function. So it is not mandetory to provide a table. Check it out this: DECLARE @cnt INT SET @cnt = COUNT(*) SELECT @cnt SET @cnt = COUNT(‘x’) SELECT @cnt Naveen Select 1 / Select ‘*’ will return 1/* as expected. Select Count(1)/Count(*) will return the count of result set of select statement. Count(1)/Count(*) will have one 1/* for each row in the result set of select statement. Select 1 or Select ‘*’ result set will contain only 1 result. so count is 1. Where as “Select *” is a sysntax which expects the table or equauivalent to table (table functions, etc..). It is like compilation error for that query. Ramesh Hi Friends, Count is an aggregate function and it expects the rows (list of records) for a specified single column or whole rows for *. So, when we use ‘select *’ it definitely give and error because ‘*’ is meant to have all the fields but there is not any table and without table it can only raise an error. So, in the case of ‘Select Count(*)’, there will be an error as a record in the count function so you will get the result as ’1'. Try using : Select COUNT(‘RAMESH’) and think there is an error ‘Must specify table to select from.’ in place of ‘RAMESH’ Pinal : If i am wrong then please clarify this. Sachin Nandanwar Any aggregate function expects a constant or a column name as an expression. DO NOT be confused with * in an aggregate function.The aggregate function does not treat it as a column name or a set of column names but a constant value, as * is a key word in SQL. You can replace any value instead of * for the COUNT function.Ex Select COUNT(5) will result as 1. The error resulting from select * is obvious it expects an object where it can extract the result set. I sincerely thank you all for wonderful conversation, I personally enjoyed it and I am sure all of you have the same feeling. Reference: Pinal Dave (http://blog.SQLAuthority.com) Filed under: CodeProject, Pinal Dave, PostADay, Readers Contribution, Readers Question, SQL, SQL Authority, SQL Puzzle, SQL Query, SQL Scripts, SQL Server, SQL Tips and Tricks, SQLServer, T SQL, Technology

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  • SQL SERVER – Simple Example to Configure Resource Governor – Introduction to Resource Governor

    - by pinaldave
    Let us jump right away with question and answer mode. What is resource governor? Resource Governor is a feature which can manage SQL Server Workload and System Resource Consumption. We can limit the amount of CPU and memory consumption by limiting /governing /throttling on the SQL Server. Why is resource governor required? If there are different workloads running on SQL Server and each of the workload needs different resources or when workloads are competing for resources with each other and affecting the performance of the whole server resource governor is a very important task. What will be the real world example of need of resource governor? Here are two simple scenarios where the resource governor can be very useful. Scenario 1: A server which is running OLTP workload and various resource intensive reports on the same server. The ideal situation is where there are two servers which are data synced with each other and one server runs OLTP transactions and the second server runs all the resource intensive reports. However, not everybody has the luxury to set up this kind of environment. In case of the situation where reports and OLTP transactions are running on the same server, limiting the resources to the reporting workload it can be ensured that OTLP’s critical transaction is not throttled. Scenario 2: There are two DBAs in one organization. One DBA A runs critical queries for business and another DBA B is doing maintenance of the database. At any point in time the DBA A’s work should not be affected but at the same time DBA B should be allowed to work as well. The ideal situation is that when DBA B starts working he get some resources but he can’t get more than defined resources. Does SQL Server have any default resource governor component? Yes, SQL Server have two by default created resource governor component. 1) Internal –This is used by database engine exclusives and user have no control. 2) Default – This is used by all the workloads which are not assigned to any other group. What are the major components of the resource governor? Resource Pools Workload Groups Classification In simple words here is what the process of resource governor is. Create resource pool Create a workload group Create classification function based on the criteria specified Enable Resource Governor with classification function Let me further explain you the same with graphical image. Is it possible to configure resource governor with T-SQL? Yes, here is the code for it with explanation in between. Step 0: Here we are assuming that there are separate login accounts for Reporting server and OLTP server. /*----------------------------------------------- Step 0: (Optional and for Demo Purpose) Create Two User Logins 1) ReportUser, 2) PrimaryUser Use ReportUser login for Reports workload Use PrimaryUser login for OLTP workload -----------------------------------------------*/ Step 1: Creating Resource Pool We are creating two resource pools. 1) Report Server and 2) Primary OLTP Server. We are giving only a few resources to the Report Server Pool as described in the scenario 1 the other server is mission critical and not the report server. ----------------------------------------------- -- Step 1: Create Resource Pool ----------------------------------------------- -- Creating Resource Pool for Report Server CREATE RESOURCE POOL ReportServerPool WITH ( MIN_CPU_PERCENT=0, MAX_CPU_PERCENT=30, MIN_MEMORY_PERCENT=0, MAX_MEMORY_PERCENT=30) GO -- Creating Resource Pool for OLTP Primary Server CREATE RESOURCE POOL PrimaryServerPool WITH ( MIN_CPU_PERCENT=50, MAX_CPU_PERCENT=100, MIN_MEMORY_PERCENT=50, MAX_MEMORY_PERCENT=100) GO Step 2: Creating Workload Group We are creating two workloads each mapping to each of the resource pool which we have just created. ----------------------------------------------- -- Step 2: Create Workload Group ----------------------------------------------- -- Creating Workload Group for Report Server CREATE WORKLOAD GROUP ReportServerGroup USING ReportServerPool ; GO -- Creating Workload Group for OLTP Primary Server CREATE WORKLOAD GROUP PrimaryServerGroup USING PrimaryServerPool ; GO Step 3: Creating user defiled function which routes the workload to the appropriate workload group. In this example we are checking SUSER_NAME() and making the decision of Workgroup selection. We can use other functions such as HOST_NAME(), APP_NAME(), IS_MEMBER() etc. ----------------------------------------------- -- Step 3: Create UDF to Route Workload Group ----------------------------------------------- CREATE FUNCTION dbo.UDFClassifier() RETURNS SYSNAME WITH SCHEMABINDING AS BEGIN DECLARE @WorkloadGroup AS SYSNAME IF(SUSER_NAME() = 'ReportUser') SET @WorkloadGroup = 'ReportServerGroup' ELSE IF (SUSER_NAME() = 'PrimaryServerPool') SET @WorkloadGroup = 'PrimaryServerGroup' ELSE SET @WorkloadGroup = 'default' RETURN @WorkloadGroup END GO Step 4: In this final step we enable the resource governor with the classifier function created in earlier step 3. ----------------------------------------------- -- Step 4: Enable Resource Governer -- with UDFClassifier ----------------------------------------------- ALTER RESOURCE GOVERNOR WITH (CLASSIFIER_FUNCTION=dbo.UDFClassifier); GO ALTER RESOURCE GOVERNOR RECONFIGURE GO Step 5: If you are following this demo and want to clean up your example, you should run following script. Running them will disable your resource governor as well delete all the objects created so far. ----------------------------------------------- -- Step 5: Clean Up -- Run only if you want to clean up everything ----------------------------------------------- ALTER RESOURCE GOVERNOR WITH (CLASSIFIER_FUNCTION = NULL) GO ALTER RESOURCE GOVERNOR DISABLE GO DROP FUNCTION dbo.UDFClassifier GO DROP WORKLOAD GROUP ReportServerGroup GO DROP WORKLOAD GROUP PrimaryServerGroup GO DROP RESOURCE POOL ReportServerPool GO DROP RESOURCE POOL PrimaryServerPool GO ALTER RESOURCE GOVERNOR RECONFIGURE GO I hope this introductory example give enough light on the subject of Resource Governor. In future posts we will take this same example and learn a few more details. Reference: Pinal Dave (http://blog.sqlauthority.com) Filed under: PostADay, SQL, SQL Authority, SQL Query, SQL Server, SQL Tips and Tricks, T SQL, Technology Tagged: Resource Governor

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  • SQL SERVER – Simple Example of Incremental Statistics – Performance improvements in SQL Server 2014 – Part 2

    - by Pinal Dave
    This is the second part of the series Incremental Statistics. Here is the index of the complete series. What is Incremental Statistics? – Performance improvements in SQL Server 2014 – Part 1 Simple Example of Incremental Statistics – Performance improvements in SQL Server 2014 – Part 2 DMV to Identify Incremental Statistics – Performance improvements in SQL Server 2014 – Part 3 In part 1 we have understood what is incremental statistics and now in this second part we will see a simple example of incremental statistics. This blog post is heavily inspired from my friend Balmukund’s must read blog post. If you have partitioned table and lots of data, this feature can be specifically very useful. Prerequisite Here are two things you must know before you start with the demonstrations. AdventureWorks – For the demonstration purpose I have installed AdventureWorks 2012 as an AdventureWorks 2014 in this demonstration. Partitions – You should know how partition works with databases. Setup Script Here is the setup script for creating Partition Function, Scheme, and the Table. We will populate the table based on the SalesOrderDetails table from AdventureWorks. -- Use Database USE AdventureWorks2014 GO -- Create Partition Function CREATE PARTITION FUNCTION IncrStatFn (INT) AS RANGE LEFT FOR VALUES (44000, 54000, 64000, 74000) GO -- Create Partition Scheme CREATE PARTITION SCHEME IncrStatSch AS PARTITION [IncrStatFn] TO ([PRIMARY], [PRIMARY], [PRIMARY], [PRIMARY], [PRIMARY]) GO -- Create Table Incremental_Statistics CREATE TABLE [IncrStatTab]( [SalesOrderID] [int] NOT NULL, [SalesOrderDetailID] [int] NOT NULL, [CarrierTrackingNumber] [nvarchar](25) NULL, [OrderQty] [smallint] NOT NULL, [ProductID] [int] NOT NULL, [SpecialOfferID] [int] NOT NULL, [UnitPrice] [money] NOT NULL, [UnitPriceDiscount] [money] NOT NULL, [ModifiedDate] [datetime] NOT NULL) ON IncrStatSch(SalesOrderID) GO -- Populate Table INSERT INTO [IncrStatTab]([SalesOrderID], [SalesOrderDetailID], [CarrierTrackingNumber], [OrderQty], [ProductID], [SpecialOfferID], [UnitPrice],   [UnitPriceDiscount], [ModifiedDate]) SELECT     [SalesOrderID], [SalesOrderDetailID], [CarrierTrackingNumber], [OrderQty], [ProductID], [SpecialOfferID], [UnitPrice],   [UnitPriceDiscount], [ModifiedDate] FROM       [Sales].[SalesOrderDetail] WHERE      SalesOrderID < 54000 GO Check Details Now we will check details in the partition table IncrStatSch. -- Check the partition SELECT * FROM sys.partitions WHERE OBJECT_ID = OBJECT_ID('IncrStatTab') GO You will notice that only a few of the partition are filled up with data and remaining all the partitions are empty. Now we will create statistics on the Table on the column SalesOrderID. However, here we will keep adding one more keyword which is INCREMENTAL = ON. Please note this is the new keyword and feature added in SQL Server 2014. It did not exist in earlier versions. -- Create Statistics CREATE STATISTICS IncrStat ON [IncrStatTab] (SalesOrderID) WITH FULLSCAN, INCREMENTAL = ON GO Now we have successfully created statistics let us check the statistical histogram of the table. Now let us once again populate the table with more data. This time the data are entered into a different partition than earlier populated partition. -- Populate Table INSERT INTO [IncrStatTab]([SalesOrderID], [SalesOrderDetailID], [CarrierTrackingNumber], [OrderQty], [ProductID], [SpecialOfferID], [UnitPrice],   [UnitPriceDiscount], [ModifiedDate]) SELECT     [SalesOrderID], [SalesOrderDetailID], [CarrierTrackingNumber], [OrderQty], [ProductID], [SpecialOfferID], [UnitPrice],   [UnitPriceDiscount], [ModifiedDate] FROM       [Sales].[SalesOrderDetail] WHERE      SalesOrderID > 54000 GO Let us check the status of the partition once again with following script. -- Check the partition SELECT * FROM sys.partitions WHERE OBJECT_ID = OBJECT_ID('IncrStatTab') GO Statistics Update Now here has the new feature come into action. Previously, if we have to update the statistics, we will have to FULLSCAN the entire table irrespective of which partition got the data. However, in SQL Server 2014 we can just specify which partition we want to update in terms of Statistics. Here is the script for the same. -- Update Statistics Manually UPDATE STATISTICS IncrStatTab (IncrStat) WITH RESAMPLE ON PARTITIONS(3, 4) GO Now let us check the statistics once again. -- Show Statistics DBCC SHOW_STATISTICS('IncrStatTab', IncrStat) WITH HISTOGRAM GO Upon examining statistics histogram, you will notice that now the distribution has changed and there is way more rows in the histogram. Summary The new feature of Incremental Statistics is indeed a boon for the scenario where there are partitions and statistics needs to be updated frequently on the partitions. In earlier version to update statistics one has to do FULLSCAN on the entire table which was wasting too many resources. With the new feature in SQL Server 2014, now only those partitions which are significantly changed can be specified in the script to update statistics. Cleanup You can clean up the database by executing following scripts. -- Clean up DROP TABLE [IncrStatTab] DROP PARTITION SCHEME [IncrStatSch] DROP PARTITION FUNCTION [IncrStatFn] GO Reference: Pinal Dave (http://blog.sqlauthority.com)Filed under: PostADay, SQL, SQL Authority, SQL Performance, SQL Query, SQL Server, SQL Tips and Tricks, T SQL Tagged: SQL Statistics, Statistics

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  • SQL SERVER – Auditing and Profiling Database Made Easy with SQL Audit and Comply

    - by Pinal Dave
    Do you like auditing your database, or can you think of about a million other things you’d rather do?  Unfortunately, auditing is incredibly important.  As with tax audits, it is important to audit databases to ensure they are following all the rules, but they are also important for troubleshooting and security. There are several ways to audit SQL Server.  There is manual auditing, which is going through your database “by hand,” and obviously takes a long time and is quite inefficient.  SQL Server also provides programs to help you audit your systems.  Different administrators will have different opinions about best practices and which tools to use, and each one will be perfected for certain systems and certain users. Today, though, I would like to talk about Apex SQL Audit.  It is an auditing tool that acts like “track changes” in a word processing document.  It will log what has changed on the database, who made the changes, and what effects these changes have had (i.e. what objects were affected down the line).  All this information is logged, and can be easily viewed or printed for easy access. One of the best features of Apex is that it is so customizable (and easy to use!).  First, start Apex.  Then you can connect to the database you would like to monitor. Once you select your database, you can select which table you want to audit. You can customize right down to the field you’d like to audit, and then select which types of actions you’d like tracked – insert, delete, or update.  Repeat these steps for every database you want monitored. To create the logs, choose “Create triggers” in the menu.  The script written here will be what logs each insert, delete, and update function.  Press F5 to execute.  All this tracking information will be stored in AUDIT_LOG_DATA and AUDIT_LOG_TRANSACTIONS tables.  View these tables using ApexSQL Audit reports. These transaction logs can be extremely detailed – especially on very busy servers, where every move it traced.  Reading them can be overwhelming, to say the least.  Apex has tried to make things easier for the average DBA, though. You can read these tracking logs in Apex, and it will display data and objects that affect your server – even things that were happening on your server before you installed Apex! To read these logs, open Apex, and connect to that database you want to audit. Go to the Transaction Logs tab, and add the logs you want to read. To narrow down what results you want to see, you can use the Filter tab to choose time, operation type, name, users, and more. Click Open, and you can see the results in a grid (as shown below).  You can export these results to CSV, HTML, XML or SQL files and save on the hard disk. One of the advantages is that since there are no triggers here, there are no other processes that will affect SQL Server performance.  Using this method is also how to view history from your database that occurred before Apex was installed.  This type of tracking does require storage space for the data sources, as the database must be fully running, and the transaction logs must exist (things not stored in the transactions logs will not be recoverable). Apex can also replace SQL Server Profiler and SQL Server Traces – which are much more complex and error-prone – with its ApexSQL Comply.  It can do fault tolerant auditing, centralized reporting, and “who saw what” information in an easy-to-use interface.  The tracking settings can be altered by the user, or the default options will provide solutions to the most common auditing problems. To get started: open ApexSQL Comply, and selected Database Filter Settings to choose which database you’d like to audit.  You can select which tracking you’re like in Operation Types – DML, DDL, queries executed, execute statements, and more.  To get started, click Start Auditing. After this, every action will be stored in the central repository database (ApexSQLCrd).  You can view the audit and create a report (or view the standard default report) using a wizard. You can see how easy it is to use ApexSQL Comply.  You can easily set audits, including the type and time, and create customized reports.  Remote users can easily access the reports through the user interface (available online, as well), and security concerns are all taken care of by the program.  Reference: Pinal Dave (http://blog.sqlauthority.com) Filed under: PostADay, SQL, SQL Authority, SQL Query, SQL Server, SQL Tips and Tricks, SQL Utility, T SQL, Technology

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  • Why do I have untrusted certificates for Google, Yahoo, Mozilla and others?

    - by jackweirdy
    In the HTTPS/SSL section of chrome://chrome/settings, I see the following: What does this mean, and is there something wrong? I have a basic understanding of SSL/TLS - I'm not claiming to be completely familiar, but I'm fairly confident I know my way around it - but I don't understand why I have certificates installed on my machine specifically for these sites. From my understanding, I should have the certificates for Certificate Authorities, and any site I visit and use SSL/TLS should have a certificate signed by one of these trusted CAs for me to trust the site. My worry is that if someone has maliciously installed a certificate for these sites on my machine, they could perform a DNS spoofing attack (or a number of other attacks) to hijack my connection to my email account without me knowing, and as they've got the private counterpart to the certificate on my machine, decrypt the communication. NB: I'm also aware that CA certificates aren't just within Chromium and are used system wide as part of libssl - they're stored in /etc/ssl/certs. What I'd like to know is: Is this correct? - The big red boxes make me think no Is this malicious or benign? What can I do to resolve this problem? (If indeed it is a problem) Thanks :)

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