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  • Understanding Column Properties for a SQL Server Table

    Designing a table can be a little complicated if you don’t have the correct knowledge of data types, relationships, and even column properties. In this tip, Brady Upton goes over the column properties and provides examples. "It really helped us isolate where we were experiencing a bottleneck"- John Q Martin, SQL Server DBA. Get started with SQL Monitor today to solve tricky performance problems - download a free trial

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  • July, the 31 Days of SQL Server DMO’s – Day 29 (sys.dm_os_buffer_descriptors)

    - by Tamarick Hill
    The sys.dm_os_buffer_descriptors Dynamic Management View gives you a look into the data pages that are currently in your SQL Server buffer pool. Just in case you are not familiar with some of the internals to SQL Server and how the engine works, SQL Server only works with objects that are in memory (buffer pool). When an object such as a table needs to be read and it does not exist in the buffer pool, SQL Server will read (copy) the necessary data page(s) from disk into the buffer pool and cache it. Caching takes place so that it can be reused again and prevents the need of expensive physical reads. To better illustrate this DMV, lets query it against our AdventureWorks2012 database and view the result set. SELECT * FROM sys.dm_os_buffer_descriptors WHERE database_id = db_id('AdventureWorks2012') The first column returned from this result set is the database_id column which identifies the specific database for a given row. The file_id column represents the file that a particular buffer descriptor belongs to. The page_id column represents the ID for the data page within the buffer. The page_level column represents the index level of the data page. Next we have the allocation_unit_id column which identifies a unique allocation unit. An allocation unit is basically a set of data pages. The page_type column tells us exactly what type of page is in the buffer pool. From my screen shot above you see I have 3 distinct type of Pages in my buffer pool, Index, Data, and IAM pages. Index pages are pages that are used to build the Root and Intermediate levels of a B-Tree. A Data page would represent the actual leaf pages of a clustered index which contain the actual data for the table. Without getting into too much detail, an IAM page is Index Allocation Map page which track GAM (Global Allocation Map) pages which in turn track extents on your system. The row_count column details how many data rows are present on a given page. The free_space_in_bytes tells you how much of a given data page is still available, remember pages are 8K in size. The is_modified signifies whether or not a page has been changed since it has been read into memory, .ie a dirty page. The numa_node column represents the Nonuniform memory access node for the buffer. Lastly is the read_microsec column which tells you how many microseconds it took for a data page to be read (copied) into the buffer pool. This is a great DMV for use when you are tracking down a memory issue or if you just want to have a look at what type of pages are currently in your buffer pool. For more information about this DMV, please see the below Books Online link: http://msdn.microsoft.com/en-us/library/ms173442.aspx Follow me on Twitter @PrimeTimeDBA

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  • Red Gate Rolls Out the Red Carpet for SQL Server Users

    SQL in the City, the unique event for database developers and administrators organized by Red Gate Software, hits the streets of London and Seattle this fall. Now in its fourth year, it features presentations by some of the world’s top SQL Server speakers. Can 41,000 DBAs really be wrong? Join 41,000 other DBAs who are following the new series from the DBA Team: the 5 Worst Days in a DBA’s Life. Part 3, As Corrupt As It Gets, is out now – read it here.

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  • Getting Dynamic in SSIS Queries

    - by ejohnson2010
    When you start working with SQL Server and SSIS, it isn’t long before you find yourself wishing you could change bits of SQL queries dynamically. Most commonly, I see people that want to change the date portion of a query so that you can limit your query to the last 30 days, for example. This can be done using a combination of expressions and variables. I will do this in two parts, first I will build a variable that will always contain the 1 st day of the previous month and then I will dynamically...(read more)

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  • Script to determine if you should update Build version

    - by NeilHambly
    Aaron Betrand has posted a great article on the Patch Tuesday Security Bulletin and I have quickly translated that into a SQL script to check your version and advise what you should be doing http://www.microsoft.com/technet/security/Bulletin/MS11-049.mspx Aaron's article: http://sqlblog.com/blogs/aaron_bertrand/archive/2011/06/14/security-updates-for-all-supported-versions-of-sql-server.aspx#comments Naturally ANY Script needs to be carefully vetted before it is used in your own environments;...(read more)

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  • More info: a "stand-alone" installer for Management Studio Express 2008

    - by AaronBertrand
    Last February, I blogged about something I was initially very happy about: a stand-alone installer for Management Studio Express (SSMSE) 2008 . Now users could allegedly download a much smaller installer, and only install the client tools without having to install an instance of SQL Server Express. While the latter is true, the former remains a pipe dream. Bill Ramos stated in his 2009-02-20 announcement : "We teased out the Tools portion of SQL Server 2008 Express with Tools into it’s own download."...(read more)

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  • Cloud Evolving, SQL Server Responding

    - by KKline
    Brent Ozar ( blog | twitter ) and I did an interview with TechTarget’s Brendan Cournoyer at last summer's Tech-Ed, which as turned into a podcast titled “Cloud efforts advance, SQL Server evolves.” The podcast covers all the major trends at the conference (like BI), virtualization features in Quest’s products (like Spotlight), Brent’s new book and MCM certification, and more. Here’s a link to hear it, appearing on 6/11/10: http://searchsqlserver.techtarget.com/podcast/Cloud-efforts-advance-SQL-Server-evolves....(read more)

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  • Intel Xeon E5 (Sandy Bridge-EP) and SQL Server 2012 Benchmarks

    - by jchang
    Intel officially announced the Xeon E5 2600 series processor based on Sandy Bridge-EP variant with upto 8 cores and 20MB LLC per socket. Only one TPC benchmark accompanied product launch, summary below. Processors Cores per Frequency Memory SQL Vendor TPC-E 2 x Xeon E5-2690 8 2.9GHz 512GB (16x32GB) 2012 IBM 1,863.23 2 x Xeon E7-2870 10 2.4GHz 512GB (32x16GB) 2008R2 IBM 1,560.70 2 x Xeon X5690 6 3.46GHz 192GB (12x16GB) 2008R2 HP 1,284.14 Note: the HP report lists SQL Server 2008 R2 Enterprise Edition...(read more)

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  • Cloud Evolving, SQL Server Responding

    - by KKline
    Brent Ozar ( blog | twitter ) and I did an interview with TechTarget’s Brendan Cournoyer at last summer's Tech-Ed, which as turned into a podcast titled “Cloud efforts advance, SQL Server evolves.” The podcast covers all the major trends at the conference (like BI), virtualization features in Quest’s products (like Spotlight), Brent’s new book and MCM certification, and more. Here’s a link to hear it, appearing on 6/11/10: http://searchsqlserver.techtarget.com/podcast/Cloud-efforts-advance-SQL-Server-evolves....(read more)

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  • SQL UserGroup Events & Service Broker

    - by NeilHambly
    I'm sure you are now aware of the SQL UserGroup events (both in London) on Wednesday 19th & Thrusday 20th evenings, If you have never been to one of the events before then I would highly reconmend attending one or both of them. Covering a wide range of subjects these meetings are an invaluable way to gain insights into various features from SQL experts (both presenters and attendees alike) frequently you will learn new insights and gain different perspectives on how to use those features...(read more)

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  • SQL Server Contains Equivalent

    - by Derek D.
    Many Oracle developers trying to find the SQL Server function compatible with their Contains clause will most likely accidently end up on this page. Therefore, this page will be devoted to them rather than the SQL Server’s Contains function which is used for full-text searching. The most similar function to Oracle’s contains is charindex. The usage [...]

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  • In defense of SELECT * in production code, in some limited cases?

    - by Alexander Kuznetsov
    It is well known that SELECT * is not acceptable in production code, with the exception of this pattern: IF EXISTS( SELECT * We all know that whenever we see code code like this: Listing 1. "Bad" SQL SELECT Column1 , Column2 FROM ( SELECT c. * , ROW_NUMBER () OVER ( PARTITION BY Column1 ORDER BY Column2 ) AS rn FROM data.SomeTable AS c ) AS c WHERE rn < 5 we are supposed to automatically replace * with an explicit list of columns, as follows: Listing 2. "Good" SQL SELECT Column1 , Column2 FROM...(read more)

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  • SQL Server MCM is too easy, is it?

    - by simonsabin
    We all know that Brent Ozar did the MCM training/certification over the past few weeks. He wrote an interesting article on Friday about the bad bits ( http://www.brentozar.com/archive/2010/04/sql-mcm-now-bad-stuff/ ) of the training and it lead me to thinking about the certification process again(I often think about it, and it appears often in response to something from Brent http://sqlblogcasts.com/blogs/simons/archive/2010/02/12/Whats-missing-in-the-SQL-Certification-process-.aspx ) This time what...(read more)

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  • PASS Summit 2012 PreCon - DBA-298-P Automate and Manage SQL Server with PowerShell

    - by AllenMWhite
    On Tuesday I presented an all-day pre-conference session on using PowerShell to automate and manage SQL Server. It was a very full day and we had a lot of great questions. One discussion in Module 6 was around scripting all the objects in a database, and I'd mentioned the script I wrote for the book The Red Gate Guide to SQL Server Team-based Development . When putting together the demos for the attendees to download I realized I'd placed that script in the Module 6 folder, so you don't need to go...(read more)

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  • SQL University: What and why of database refactoring

    - by Mladen Prajdic
    This is a post for a great idea called SQL University started by Jorge Segarra also famously known as SqlChicken on Twitter. It’s a collection of blog posts on different database related topics contributed by several smart people all over the world. So this week is mine and we’ll be talking about database testing and refactoring. In 3 posts we’ll cover: SQLU part 1 - What and why of database testing SQLU part 2 - What and why of database refactoring SQLU part 3 - Tools of the trade This is a second part of the series and in it we’ll take a look at what database refactoring is and why do it. Why refactor a database To know why refactor we first have to know what refactoring actually is. Code refactoring is a process where we change module internals in a way that does not change that module’s input/output behavior. For successful refactoring there is one crucial thing we absolutely must have: Tests. Automated unit tests are the only guarantee we have that we haven’t broken the input/output behavior before refactoring. If you haven’t go back ad read my post on the matter. Then start writing them. Next thing you need is a code module. Those are views, UDFs and stored procedures. By having direct table access we can kiss fast and sweet refactoring good bye. One more point to have a database abstraction layer. And no, ORM’s don’t fall into that category. But also know that refactoring is NOT adding new functionality to your code. Many have fallen into this trap. Don’t be one of them and resist the lure of the dark side. And it’s a strong lure. We developers in general love to add new stuff to our code, but hate fixing our own mistakes or changing existing code for no apparent reason. To be a good refactorer one needs discipline and focus. Now we know that refactoring is all about changing inner workings of existing code. This can be due to performance optimizations, changing internal code workflows or some other reason. This is a typical black box scenario to the outside world. If we upgrade the car engine it still has to drive on the road (preferably faster) and not fly (no matter how cool that would be). Also be aware that white box tests will break when we refactor. What to refactor in a database Refactoring databases doesn’t happen that often but when it does it can include a lot of stuff. Let us look at a few common cases. Adding or removing database schema objects Adding, removing or changing table columns in any way, adding constraints, keys, etc… All of these can be counted as internal changes not visible to the data consumer. But each of these carries a potential input/output behavior change. Dropping a column can result in views not working anymore or stored procedure logic crashing. Adding a unique constraint shows duplicated data that shouldn’t exist. Foreign keys break a truncate table command executed from an application that runs once a month. All these scenarios are very real and can happen. With the proper database abstraction layer fully covered with black box tests we can make sure something like that does not happen (hopefully at all). Changing physical structures Physical structures include heaps, indexes and partitions. We can pretty much add or remove those without changing the data returned by the database. But the performance can be affected. So here we use our performance tests. We do have them, right? Just by adding a single index we can achieve orders of magnitude performance improvement. Won’t that make users happy? But what if that index causes our write operations to crawl to a stop. again we have to test this. There are a lot of things to think about and have tests for. Without tests we can’t do successful refactoring! Fixing bad code We all have some bad code in our systems. We usually refer to that code as code smell as they violate good coding practices. Examples of such code smells are SQL injection, use of SELECT *, scalar UDFs or cursors, etc… Each of those is huge code smell and can result in major code changes. Take SELECT * from example. If we remove a column from a table the client using that SELECT * statement won’t have a clue about that until it runs. Then it will gracefully crash and burn. Not to mention the widely unknown SELECT * view refresh problem that Tomas LaRock (@SQLRockstar on Twitter) and Colin Stasiuk (@BenchmarkIT on Twitter) talk about in detail. Go read about it, it’s informative. Refactoring this includes replacing the * with column names and most likely change to application using the database. Breaking apart huge stored procedures Have you ever seen seen a stored procedure that was 2000 lines long? I have. It’s not pretty. It hurts the eyes and sucks the will to live the next 10 minutes. They are a maintenance nightmare and turn into things no one dares to touch. I’m willing to bet that 100% of time they don’t have a single test on them. Large stored procedures (and functions) are a clear sign that they contain business logic. General opinion on good database coding practices says that business logic has no business in the database. That’s the applications part. Refactoring such behemoths requires writing lots of edge case tests for the stored procedure input/output behavior and then start to refactor it. First we split the logic inside into smaller parts like new stored procedures and UDFs. Those then get called from the master stored procedure. Once we’ve successfully modularized the database code it’s best to transfer that logic into the applications consuming it. This only leaves the stored procedure with common data manipulation logic. Of course this isn’t always possible so having a plethora of performance and behavior unit tests is absolutely necessary to confirm we’ve actually improved the codebase in some way.   Refactoring is not a popular chore amongst developers or managers. The former don’t like fixing old code, the latter can’t see the financial benefit. Remember how we talked about being lousy at estimating future costs in the previous post? But there comes a time when it must be done. Hopefully I’ve given you some ideas how to get started. In the last post of the series we’ll take a look at the tools to use and an example of testing and refactoring.

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  • Configuring SQL Server Audit Logging with Powershell

    - by Jonathan Kehayias
    One of the standard configuration options that I set on all SQL Server installs is to log Failed Login Attempts to the SQL Server Error Log.  I recently inherited an environment that this option wasn’t standardized across all of the servers and needed to configure it for multiple servers in a scripted manner.  There are a couple of ways to handle this kind of task.  First I could log on to every server in SSMS, open the Server Properties, and set the option on the Security sheet for...(read more)

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  • Handy SQL Server Function Series: Part 1

    - by Most Valuable Yak (Rob Volk)
    I've been preparing to give a presentation on SQL Server for a while now, and a topic that was recommended was SQL Server functions.  More specifically, the lesser-known functions (like @@OPTIONS), and maybe some interesting ways to use well-known functions (like using PARSENAME to split IP addresses)  I think this is a veritable goldmine of useful information, and researching for the presentation has confirmed that beyond my initial expectations.I even found a few undocumented/underdocumented functions, so for the first official article in this series I thought I'd start with 2 of each, COLLATIONPROPERTY() and COLLATIONPROPERTYFROMID().COLLATIONPROPERTY() provides information about (wait for it) collations, SQL Server's method for handling foreign character sets, sort orders, and case- or accent-sensitivity when sorting character data.  The Books Online entry for  COLLATIONPROPERTY() lists 4 options for code page, locale ID, comparison style and version.  Used in conjunction with fn_helpcollations():SELECT *, COLLATIONPROPERTY(name,'LCID') LCID, COLLATIONPROPERTY(name,'CodePage') CodePage, COLLATIONPROPERTY(name,'ComparisonStyle') ComparisonStyle, COLLATIONPROPERTY(name,'Version') Version FROM fn_helpcollations()You can get some excellent information. (c'mon, be honest, did you even know about fn_helpcollations?)Collations in SQL Server have a unique name and ID, and you'll see one or both in various system tables or views like syscolumns, sys.columns, and INFORMATION_SCHEMA.COLUMNS.  Unfortunately they only link the ID and name for collations of existing columns, so if you wanted to know the collation ID of Albanian_CI_AI_WS, you'd have to declare a column with that collation and query the system table.While poking around the OBJECT_DEFINITION() of sys.columns I found a reference to COLLATIONPROPERTYFROMID(), and the unknown property "Name".  Not surprisingly, this is how sys.columns finds the name of the collation, based on the ID stored in the system tables.  (Check yourself if you don't believe me)Somewhat surprisingly, the "Name" property also works for COLLATIONPROPERTY(), although you'd already know the name at that point.  Some wild guesses and tests revealed that "CollationID" is also a valid property for both functions, so now:SELECT *, COLLATIONPROPERTY(name,'LCID') LCID, COLLATIONPROPERTY(name,'CodePage') CodePage, COLLATIONPROPERTY(name,'ComparisonStyle') ComparisonStyle, COLLATIONPROPERTY(name,'Version') Version, COLLATIONPROPERTY(name,'CollationID') CollationID FROM fn_helpcollations() Will get you the collation ID-name link you…probably didn't know or care about, but if you ever get on Jeopardy! and this question comes up, feel free to send some of your winnings my way. :)And last but not least, COLLATIONPROPERTYFROMID() uses the same properties as COLLATIONPROPERTY(), so you can use either one depending on which value you have available.Keep an eye out for Part 2!

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  • SQL Server overload in London in June

    - by simonsabin
    After the awesome SQLSocial last night in London we are just about to announce another event next week but in the mean time Paul and Kimberly are doing an Immersion event by Heathrow and have said anyone can come along on the Tuesday or Wednesday nights. If you want to pop along register quick before the space fills up. The event is being held at the Renaissance London Heathrow Hotel .  21 June 2011: Tuesday evening SQL Sentry will present: Tips for Query Tuning with SQL Sentry Plan Explorer...(read more)

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  • Temp Table Recompiles

    - by Derek D.
    If you landed on this article, then you most likely know that temp tables can cause recompilation. This happens because temp tables are treated just like regular tables by the SQL Server Engine. When the tables (in which underlying queries rely on) change significantly, SQL Server detects this change (using auto update statistics) [...]

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  • Secret of SQL Trace Duration Column

    - by Dan Guzman
    Why would a trace of long-running queries not show all queries that exceeded the specified duration filter?  We have a server-side SQL Trace that includes RPC:Completed and SQL:BatchCompleted events with a filter on Duration >= 100000.  Nearly all of the queries on this busy OLTP server run in under this 100 millisecond threshold so any that appear in the trace are candidates for root cause analysis and/or performance tuning opportunities. After an application experienced query timeouts, the DBA looked at the trace data to corroborate the problem.  Surprisingly, he found no long-running queries in the trace from the application that experienced the timeouts even though the application’s error log clearly showed detail of the problem (query text, duration, start time, etc.).  The trace did show, however, that there were hundreds of other long-running queries from different applications during the problem timeframe.  We later determined those queries were blocked by a large UPDATE query against a critical table that was inadvertently run during this busy period. So why didn’t the trace include all of the long-running queries?  The reason is because the SQL Trace event duration doesn’t include the time a request was queued while awaiting a worker thread.  Remember that the server was under considerable stress at the time due to the severe blocking episode.  Most of the worker threads were in use by blocked queries and new requests were queued awaiting a worker to free up (a DMV query on the DAC connection will show this queuing: “SELECT scheduler_id, work_queue_count FROM sys.dm_os_schedulers;”).  Technically, those queued requests had not started.  As worker threads became available, queries were dequeued and completed quickly.  These weren’t included in the trace because the duration was under the 100ms duration filter.  The duration reflected the time it took to actually run the query but didn’t include the time queued waiting for a worker thread. The important point here is that duration is not end-to-end response time.  Duration of RPC:Completed and SQL:BatchCompleted events doesn’t include time before a worker thread is assigned nor does it include the time required to return the last result buffer to the client.  In other words, duration only includes time after the worker thread is assigned until the last buffer is filled.  But be aware that duration does include the time need to return intermediate result set buffers back to the client, which is a factor when large query results are returned.  Clients that are slow in consuming results sets can increase the duration value reported by the trace “completed” events.

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  • Managing Slowly Changing Dimension with MERGE Statement in SQL Server

    Slowly Changing Dimension (SCD) Transformation is a quick and easy way to manage smaller slowly changing dimensions but it has several limitations and does not perform well when the number of rows or columns gets larger. Arshad Ali explores some of the alternatives you can use for managing larger slowly changing dimensions. How to automate your .NET and SQL Server deploymentsDeploy .NET code and SQL Server databases in a single repeatable process with Red Gate Deployment Manager. Start deploying with a 28-day trial.

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  • SQL Down Under Podcast 50 - Guest Louis Davidson now online

    - by Greg Low
    Hi Folks,I've recorded an interview today with SQL Server MVP Louis Davidson. In it, Louis discusses some of his thoughts on database design and his latest book.You'll find the podcast here: http://www.sqldownunder.com/Resources/Podcast.aspxAnd you'll find his latest book (Pro SQL Server 2012 Relational Database Design and Implementation) here: http://www.amazon.com/Server-Relational-Database-Implementation-Professional/dp/1430236957/ref=sr_1_2?ie=UTF8&qid=1344997477&sr=8-2&keywords=louis+davidsonEnjoy!

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  • Looking for a Lead SQL Developer with a passion for data

    - by simonsabin
    Data is a huge part of what we do and I need someone that has a passion for data to lead our SQL team. If you’ve got experience with SQL and want to lead a team working in an agile environment with aggressive CI processes. Do you have a passion about data and want to use technology to solve problems then you are just the person I am looking for The role is based in London working for on of the top tech companies in Europe. Contact me though my blog or linkedin ( http://uk.linkedin.com/in/simonsabin...(read more)

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  • SQL Server Substr Equivalent

    - by Derek D.
    The oracle function equivalent to the SQL Server function of Substr is: Substring. All spelled out. This function is actually identical to Oracle’s function.DECLARE @BaseString varchar(max)SET @BaseString = 'My grandmothers pillows are blue'SELECT SUBSTRING ( @BaseString -- The base string to extract from ,4 -- Start Position ,5 -- Length of Characters )The above query returns the value ‘grand’. Related Posts:»SQL Server Contains [...]

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  • Please allow us to cancel loading of log in SQL Server Management Studio Log Viewer

    - by simonsabin
    The log viewer in management studio is really neat, however if you have large log files or are accessing a remote server over a slow connection it can take a long time to load the log records. Generally you only need the last x records, so you don’t need to load all the records. It would be great to have a cancel button to allow us to cancel the loading of the log records in SQL Server Management Studio. As an aside one of the best features in SQL 2005 was the ability to cancel your connection attempt...(read more)

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