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  • Optimize bootup sequence

    - by ubuntudroid
    I'm on Ubuntu 11.04 (upgraded from 10.10) and suffering really high bootup times. It got so annoying, that I decided to dive into bootchart analysis myself. Therefore I installed bootchart and restarted the system which generated this chart. However, I'm not really experienced in reading such stuff. What causes the long bootup sequence? Edit: Here is the output of hdparm -i /dev/sda: /dev/sda: Model=SAMSUNG HD501LJ, FwRev=CR100-12, SerialNo=S0MUJ1EQ102621 Config={ Fixed } RawCHS=16383/16/63, TrkSize=34902, SectSize=554, ECCbytes=4 BuffType=DualPortCache, BuffSize=16384kB, MaxMultSect=16, MultSect=16 CurCHS=16383/16/63, CurSects=16514064, LBA=yes, LBAsects=976773168 IORDY=on/off, tPIO={min:120,w/IORDY:120}, tDMA={min:120,rec:120} PIO modes: pio0 pio1 pio2 pio3 pio4 DMA modes: mdma0 mdma1 mdma2 UDMA modes: udma0 udma1 udma2 udma3 udma4 udma5 *udma6 AdvancedPM=no WriteCache=enabled Drive conforms to: unknown: ATA/ATAPI-3,4,5,6,7 * signifies the current active mode And here the output of hdparm -tT /dev/sda /dev/sda: Timing cached reads: 2410 MB in 2.00 seconds = 1205.26 MB/sec Timing buffered disk reads: 258 MB in 3.02 seconds = 85.50 MB/sec

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  • How much isometric sprites can one optimize by mirroring and alike?

    - by Tom
    I am working on a basic isometric game, and am struggling to find the correct mirrors. I have managed to get SE out of SW, by scaling the sprite on X axis by -1. Same applies for NE angle. Something is bugging me, that I should be able to also mirror N to S, but I cannot manage to pull this one off. Am I just too sleepy and trying to do the impossible, or a basic -1 scale on Y axis is not enough? What are the common used mirror table for optimizing 8 angle (N, NE, E, SE, S, SW, W, NW) isometric sprites?

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  • Structuring Access Control In Hierarchical Object Graph

    - by SB2055
    I have a Folder entity that can be Moderated by users. Folders can contain other folders. So I may have a structure like this: Folder 1 Folder 2 Folder 3 Folder 4 I have to decide how to implement Moderation for this entity. I've come up with two options: Option 1 When the user is given moderation privileges to Folder 1, define a moderator relationship between Folder 1 and User 1. No other relationships are added to the db. To determine if the user can moderate Folder 3, I check and see if User 1 is the moderator of any parent folders. This seems to alleviate some of the complexity of handling updates / moved entities / additions under Folder 1 after the relationship has been defined, and reverting the relationship means I only have to deal with one entity. Option 2 When the user is given moderation privileges to Folder 1, define a new relationship between User 1 and Folder 1, and all child entities down to the grandest of grandchildren when the relationship is created, and if it's ever removed, iterate back down the graph to remove the relationship. If I add something under Folder 2 after this relationship has been made, I just copy all Moderators into the new Entity. But when I need to show only the top-level Folders that a user is Moderating, I need to query all folders that have a parent folder that the user does not moderate, as opposed to option 1, where I just query any items that the user is moderating. Thoughts I think it comes down to determining if users will be querying for all parent items more than they'll be querying child items... if so, then option 1 seems better. But I'm not sure. Is either approach better than the other? Why? Or is there another approach that's better than both? I'm using Entity Framework in case it matters.

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  • How to reverse engineer the SEO on a website?

    - by Startup Crazy
    I have read this question. My question is a bit different from it. I want to know how can I reverse engineer another website that is ranking the best for some keywords. For example some website called www.bla.com is there and it ranks high for many keywords and I want to learn from it how can my website be of the same authority and get the same ranking (or probably better ranking if I found something that they are missing). Can anyone enlist it as a procedure, how to reverse engineer a website?

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  • Google Analitycs says source is Search Engine (100%)

    - by Angel Estrada
    I have a problem with my google analytics code, 'cause it says since 2 months that all traffic of my websites is directly from search engine, i'm really sure that must be a mistake 'cause i have made some email marketing and landing page campaing that could help to create referal traffic, maybe somethink goes wrong with the new version of the analytics or i forgot some settings. please any help is aceptable

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  • Introduction to the SQL Server Analysis Services Neural Network Data Mining Algorithm

    In data mining and machine learning circles, the neural network is one of the most difficult algorithms to explain. Fortunately, SQL Server Analysis Services allows for a simple implementation of the algorithm for data analytics. Dallas Snider explains 24% of devs don’t use database source control – make sure you aren’t one of themVersion control is standard for application code, but databases haven’t caught up. So what steps can you take to put your SQL databases under version control? Why should you start doing it? Read more to find out…

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  • How do I swap two objects in a GC language without triggering GC?

    - by TenFour04
    I have two array lists. that I want to swap each frame. My question is, does the variable 'temp' need to be a member variable to avoid triggering GC, assuming this method is called on dozens of objects each frame? I'm not creating a new object, just a new reference to an object. public void LateUpdate(){ ArrayList<int> temp = previousFrameCollisions; previousFrameCollisions = currentFrameCollisions; currentFrameCollisions = temp; currentFrameCollisions.clear(); } I've been told there's no reason to make a primitive into a member variable just to avoid GC, so my best guess is that this also applies to object references.

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  • Improving python code

    - by cobie
    I just answered the question on project euler about finding circular primes below 1 million using python. My solution is below. I was able to reduce the running time of the solution from 9 seconds to about 3 seconds. I would like to see what else can be done to the code to reduce its running time further. This is strictly for educational purposes and for fun. import math import time def getPrimes(n): """returns set of all primes below n""" non_primes = [j for j in range(4, n, 2)] # 2 covers all even numbers for i in range(3, n, 2): non_primes.extend([j for j in range(i*2, n, i)]) return set([i for i in range(2, n)]) - set(non_primes) def getCircularPrimes(n): primes = getPrimes(n) is_circ = [] for prime in primes: prime_str = str(prime) iter_count = len(prime_str) - 1 rotated_num = [] while iter_count > 0: prime_str = prime_str[1:] + prime_str[:1] rotated_num.append(int(prime_str)) iter_count -= 1 if primes >= set(rotated_num): is_circ.append(prime) return len(is_circ)

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  • What amount of PHP memory usage is reasonable for multiple WordPress sites? [closed]

    - by John
    It seems like I've been plagued with memory usage issues most of the time I've been blogging (7 years). I upgraded my hosting to a HostGator VPS and still seem to have issues. I have about a dozen WP 3.4.2 sites running within a single account. Each has a separate installation. I finally installed TPC! Memory Usage within one of my WP installs to see what was going on. The memory usage just standing still is on the order of 40 MB. This seems high, but I don't know. What would be a reasonable memory usage for these WP installs? Do I need to take other things into account, or am I even looking at it the right way?

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  • How can you identify duplicate CSS rules?

    - by DanMan
    I'm not talking about used/unused here. I have two stylesheets and some rules differ (either in selectors, rules or both) and some are exactly the same. So I'm looking for a way to extract and move those rules, which are the same in both files, into a third stylesheet. In other words: an intersection of two stylesheets. Strangely, I couldn't find a software for this. Would have expected this to be a more common problem. Background, for those who care: I'm converting a desktop website into a mobile one and I've started by duplicating the desktop stylesheet and changing it (throwing stuff out, adding to it).

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  • Tune Your Indexing Strategy with SQL Server DMVs

    SQL Server Indexes need to be effective. It is wrong to have too few or too many. The ones you create must ensure that the workload reads the data quickly with a minimum of I/O. As well as a sound knowledge of the way that relational databases work, it helps to be familiar with the Dynamic Management Objects that are there to assist with your indexing strategy. New! SQL Backup Pro 7.2 - easy, automated backup and restoresTry out the latest features and get faster, smaller, verified backups. Download a free trial.

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  • SQL Saturday #248 Tampa

    SQLSaturday BI & Big Data Edition is a free training event for everyone interested in learning about Business Intelligence & Big Data with a focus in the Microsoft SQL Server platform. This event will be held November 9th, 2013. In addition to our Saturday free event, we will also host four paid full day pre-conferences. Want faster, smaller backups you can rely on? Use SQL Backup Pro for up to 95% compression, faster file transfer and integrated DBCC CHECKDB. Download a free trial now.

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  • SQL Injection: How it Works and How to Thwart it

    This is an extract from the book Tribal SQL. In this article, Kevin Feasel explains SQL injection attacks, how to defend against them, and how to keep your Chief Information Security Officer from appearing on the nightly news. NEW! The DBA Team in The Girl with the Backup TattooPina colada in the disk drives! How could any DBA do such a thing? And can the DBA Team undo the damage? Find out in Part 2 of their new series, 5 Worst Days in a DBA’s Life. Read the new article now.

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  • Lipoaspiration in your SQL Server Database

    Once, when disk space was at a premium, DBAs fought hard to keep the size of their database down. Now there seems less motivation to 'fight the flab' of a database. Fabiano Amorim was watching television recently when the subject matter, cosmetic surgery, gave him the theme and inspiration for this guide to keeping your database fit and trim. Free trial of SQL Backup™“SQL Backup was able to cut down my backup time significantly AND achieved a 90% compression at the same time!” Joe Cheng. Download a free trial now.

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  • How do I swap two objects in C# (specifically Mono) without triggering GC?

    - by TenFour04
    I have two array lists. that I want to swap each frame. My question is, does the variable 'temp' need to be a member variable to avoid triggering GC, assuming this method is called on dozens of objects each frame? I'm not creating a new object, just a new reference to an object. public void LateUpdate(){ ArrayList<int> temp = previousFrameCollisions; previousFrameCollisions = currentFrameCollisions; currentFrameCollisions = temp; currentFrameCollisions.clear(); } I've been told there's no reason to make a primitive into a member variable just to avoid GC, so my best guess is that this also applies to object references.

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  • Minimizing use of paper

    - by Abody97
    I've recently faced this problem in a dynamic programming curriculum, and I honestly have no idea about how to determine the appropriate state. You're given N (1 <= N <= 70) paragraphs and M (1 <= M <= N) figures. Each paragraph i requires PL_i (1 <= PL_i <= 100) lines and references at most one figure. Each figure is referenced exactly once (i.e., no two paragraphs can reference the same figure, and for each figure there's a paragraph that references it.) Each figure requires PF_i (1 <= PF_i <= 100) lines. The task is to distribute those figures and paragraphs on paper in the order they're given, where one paper fits for L lines at most. No paragraph or figure is too large to fit on one paper. If a paragraph x placed on paper x_p references a figure y then y must be placed on either the paper x_p - 1 or x_p or x_p + 1. We have to find the minimum number of lines (and thus pages) to allocate in order to distribute all the figures and paragraphs. Any help would be extremely appreciated. Thanks in advance!

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  • Looking for SQL People

    - by simonsabin
    I’m looking for 2 SQL people to join our data team. I need people that are keen to develop an exciting data platform with strong SQL skills. Desirable skills are MDX/SSAS, data warehousing and working in finance industry. The role is a full time role based in London. If you are interested then let me know either via my http://sqlblogcasts.com/blogs/simons/contact.aspx or via twitter @simon_sabin https://twitter.com/intent/tweet?screen_name=simon_sabin&text=Read your blog send me details . No...(read more)

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  • Using Friendly Names for SQL Servers via DNS

    Wouldn't it be great if your HR folks only had to put in HR-SQL.mydomain.com for the database connection in their reports? They wouldn't have to remember it was on server Nile and they certainly wouldn't have to change their reports if you migrated their database from the Nile server to the server named Danube. In DNS there are two easy ways to do this. New! SQL Monitor 3.0 Red Gate's multi-server performance monitoring and alerting tool gets results from Day One.Simple to install and easy to use – download a free trial today.

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  • Setting Up Your SQL Server Agent Correctly

    It is important to set up SQL Server Agent Security on the principles of 'executing with minimum privileges’, and ensure that errors are properly logged and alerts are set up for a comprehensive range of errors. SQL Server Agent allows fine-grained control of every job step that should allow tasks to be run entirely safely even if they occasionally need special privileges. 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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  • Fragmented Log files could be slowing down your database

    - by Fatherjack
    Something that is sometimes forgotten by a lot of DBAs is the fact that database log files get fragmented in the same way that you get fragmentation in a data file. The cause is very different but the effect is the same – too much effort reading and writing data. Data files get fragmented as data is changed through normal system activity, INSERTs, UPDATEs and DELETEs cause fragmentation and most experienced DBAs are monitoring their indexes for fragmentation and dealing with it accordingly. However, you don’t hear about so many working on their log files. How can a log file get fragmented? I’m glad you asked. When you create a database there are at least two files created on the disk storage; an mdf for the data and an ldf for the log file (you can also have ndf files for extra data storage but that’s off topic for now). It is wholly possible to have more than one log file but in most cases there is little point in creating more than one as the log file is written to in a ‘wrap-around’ method (more on that later). When a log file is created at the time that a database is created the file is actually sub divided into a number of virtual log files (VLFs). The number and size of these VLFs depends on the size chosen for the log file. VLFs are also created in the space added to a log file when a log file growth event takes place. Do you have your log files set to auto grow? Then you have potentially been introducing many VLFs into your log file. Let’s get to see how many VLFs we have in a brand new database. USE master GO CREATE DATABASE VLF_Test ON ( NAME = VLF_Test, FILENAME = 'C:\Program Files\Microsoft SQL Server\MSSQL10.ROCK_2008\MSSQL\DATA\VLF_Test.mdf', SIZE = 100, MAXSIZE = 500, FILEGROWTH = 50 ) LOG ON ( NAME = VLF_Test_Log, FILENAME = 'C:\Program Files\Microsoft SQL Server\MSSQL10.ROCK_2008\MSSQL\DATA\VLF_Test_log.ldf', SIZE = 5MB, MAXSIZE = 250MB, FILEGROWTH = 5MB ); go USE VLF_Test go DBCC LOGINFO; The results of this are firstly a new database is created with specified files sizes and the the DBCC LOGINFO results are returned to the script editor. The DBCC LOGINFO results have plenty of interesting information in them but lets first note there are 4 rows of information, this relates to the fact that 4 VLFs have been created in the log file. The values in the FileSize column are the sizes of each VLF in bytes, you will see that the last one to be created is slightly larger than the others. So, a 5MB log file has 4 VLFs of roughly 1.25 MB. Lets alter the CREATE DATABASE script to create a log file that’s a bit bigger and see what happens. Alter the code above so that the log file details are replaced by LOG ON ( NAME = VLF_Test_Log, FILENAME = 'C:\Program Files\Microsoft SQL Server\MSSQL10.ROCK_2008\MSSQL\DATA\VLF_Test_log.ldf', SIZE = 1GB, MAXSIZE = 25GB, FILEGROWTH = 1GB ); With a bigger log file specified we get more VLFs What if we make it bigger again? LOG ON ( NAME = VLF_Test_Log, FILENAME = 'C:\Program Files\Microsoft SQL Server\MSSQL10.ROCK_2008\MSSQL\DATA\VLF_Test_log.ldf', SIZE = 5GB, MAXSIZE = 250GB, FILEGROWTH = 5GB ); This time we see more VLFs are created within our log file. We now have our 5GB log file comprised of 16 files of 320MB each. In fact these sizes fall into all the ranges that control the VLF creation criteria – what a coincidence! The rules that are followed when a log file is created or has it’s size increased are pretty basic. If the file growth is lower than 64MB then 4 VLFs are created If the growth is between 64MB and 1GB then 8 VLFs are created If the growth is greater than 1GB then 16 VLFs are created. Now the potential for chaos comes if the default values and settings for log file growth are used. By default a database log file gets a 1MB log file with unlimited growth in steps of 10%. The database we just created is 6 MB, let’s add some data and see what happens. USE vlf_test go -- we need somewhere to put the data so, a table is in order IF OBJECT_ID('A_Table') IS NOT NULL DROP TABLE A_Table go CREATE TABLE A_Table ( Col_A int IDENTITY, Col_B CHAR(8000) ) GO -- Let's check the state of the log file -- 4 VLFs found EXECUTE ('DBCC LOGINFO'); go -- We can go ahead and insert some data and then check the state of the log file again INSERT A_Table (col_b) SELECT TOP 500 REPLICATE('a',2000) FROM sys.columns AS sc, sys.columns AS sc2 GO -- insert 500 rows and we get 22 VLFs EXECUTE ('DBCC LOGINFO'); go -- Let's insert more rows INSERT A_Table (col_b) SELECT TOP 2000 REPLICATE('a',2000) FROM sys.columns AS sc, sys.columns AS sc2 GO 10 -- insert 2000 rows, in 10 batches and we suddenly have 107 VLFs EXECUTE ('DBCC LOGINFO'); Well, that escalated quickly! Our log file is split, internally, into 107 fragments after a few thousand inserts. The same happens with any logged transactions, I just chose to illustrate this with INSERTs. Having too many VLFs can cause performance degradation at times of database start up, log backup and log restore operations so it’s well worth keeping a check on this property. How do we prevent excessive VLF creation? Creating the database with larger files and also with larger growth steps and actively choosing to grow your databases rather than leaving it to the Auto Grow event can make sure that the growths are made with a size that is optimal. How do we resolve a situation of a database with too many VLFs? This process needs to be done when the database is under little or no stress so that you don’t affect system users. The steps are: BACKUP LOG YourDBName TO YourBackupDestinationOfChoice Shrink the log file to its smallest possible size DBCC SHRINKFILE(FileNameOfTLogHere, TRUNCATEONLY) * Re-size the log file to the size you want it to, taking in to account your expected needs for the coming months or year. ALTER DATABASE YourDBName MODIFY FILE ( NAME = FileNameOfTLogHere, SIZE = TheSizeYouWantItToBeIn_MB) * – If you don’t know the file name of your log file then run sp_helpfile while you are connected to the database that you want to work on and you will get the details you need. The resize step can take quite a while This is already detailed far better than I can explain it by Kimberley Tripp in her blog 8-Steps-to-better-Transaction-Log-throughput.aspx. The result of this will be a log file with a VLF count according to the bullet list above. Knowing when VLFs are being created By complete coincidence while I have been writing this blog (it’s been quite some time from it’s inception to going live) Jonathan Kehayias from SQLSkills.com has written a great article on how to track database file growth using Event Notifications and Service Broker. I strongly recommend taking a look at it as this is going to catch any sneaky auto grows that take place and let you know about them right away. Hassle free monitoring of VLFs If you are lucky or wise enough to be using SQL Monitor or another monitoring tool that let’s you write your own custom metrics then you can keep an eye on this very easily. There is a custom metric for VLFs (written by Stuart Ainsworth) already on the site and there are some others there are very useful so take a moment or two to look around while you are there. Resources MSDN – http://msdn.microsoft.com/en-us/library/ms179355(v=sql.105).aspx Kimberly Tripp from SQLSkills.com – http://www.sqlskills.com/BLOGS/KIMBERLY/post/8-Steps-to-better-Transaction-Log-throughput.aspx Thomas LaRock at Simple-Talk.com – http://www.simple-talk.com/sql/database-administration/monitoring-sql-server-virtual-log-file-fragmentation/ Disclosure I am a Friend of Red Gate. This means that I am more than likely to say good things about Red Gate DBA and Developer tools. No matter how awesome I make them sound, take the time to compare them with other products before you contact the Red Gate sales team to make your order.

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