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  • Bloggers Behaving Badly

    - by andyleonard
    Introduction The other morning I awoke and said to myself, "Self, you need a million bucks." After breakfast, I waltzed down to the local bank. I slipped into the vault and managed to grab a million bucks while no one was paying attention. Quietly, I slipped out of the vault and made it home with the money. My logic? The money was there for the taking, as evidenced by my ability to go and take it. I plan to donate some of the money to charity. Worst-case: If the bank wants the money back, they'll...(read more)

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  • Thoughts on Nexus in SQL Server PDW

    - by jamiet
    I have been on a SQL Server Parallel Data Warehouse (aka PDW) training course this week and was interested to learn that you can't (yet) use SQL Server Management Studio (SSMS) against PDW, instead they ship a 3rd party tool called Nexus Chameleon. This was a bit of a disappointment at the beginning of the week (I'd prefer parity across SQL Server editions) but actually, having used Nexus for 3 days, I'm rather getting used to it. Some of it is a bit clunky (e.g. everything goes via an ODBC DSN) but once you get into using it its the epitome of "it just works". For example, over the past few years I have come to rely on intellisense in SSMS and have learnt to cope with its nuances. There is no intellisense in Nexus but you know what....I don't really miss it that much. In a sense its a breath of fresh air not having to hope that you've crossed the line into that will it work/won't it work grey area with SSMS intellisense. And I don't end up with writing @@CONNECTIONS instead of FROM anymore (anyone else suffer from this?) :) Moreover, Nexus is a standalone tool. Its not a bunch of features shoehorned into something else (Visual Studio). Another thing I like about Nexus is that you can actually do something with your resultset client-side. Take a look at the screenshots below:   You can see Nexus allows you to group a resultest by a column or set of columns. Nice touch. I know that many people have submitted Connect requests asking for the ability to do similar things in SSMS that would mean we don't have to copy resultsets into Excel (I know I have) - Nexus is a step in that direction. Its refreshing to use a tool that just gets out of the way yet still has some really useful features. How ironic that it gets shipped inside an edition of SQL Server! If I had the option of using Nexus in my day job I suspect that over time I would probably gravitate back to SSMS because as yet I haven’t really stretched Nexus’ capabilities, overall SSMS *does* have more features and up until now I've never really had any objections to it ... but its been an interesting awakening into the nuances that plague SSMS. Anyone else used Nexus? Any thoughts on it? @Jamiet

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  • July, the 31 Days of SQL Server DMO’s – Day 28 (sys.dm_db_stats_properties)

    - by Tamarick Hill
    The sys.dm_db_stats_properties Dynamic Management Function returns information about the statistics that are currently on your database objects. This function takes two parameters, an object_id and a stats_id. Let’s have a look at the result set from this function against the AdventureWorks2012.Sales.SalesOrderHeader table. To obtain the object_id and stats_id I will use a CROSS APPLY with the sys.stats system table. SELECT sp.* FROM sys.stats s CROSS APPLY sys.dm_db_stats_properties(s.object_id, s.Stats_id) sp WHERE sp.object_id = object_id('Sales.SalesOrderHeader') The first two columns returned by this function are the object_id and the stats_id columns. The next column, ‘last_updated’, gives you the date and the time that a particular statistic was last updated. The next column, ‘rows’, gives you the total number of rows in the table as of the last statistic update date. The ‘rows_sampled’ column gives you the number of rows that were sampled to create the statistic. The ‘steps’ column represents the number of specific value ranges from the statistic histogram. The ‘unfiltered_rows’ column represents the number of rows before any filters are applied. If a particular statistic is not filtered, the ‘unfiltered_rows’ column will always equal the ‘rows’ column. Lastly we have the ‘modification_counter’ column which represents the number of modification to the leading column in a given statistic since the last time the statistic was updated. Probably the most important column from this Dynamic Management Function is the ‘last_updated’ column. You want to always ensure that you have accurate and updated statistics on your database objects. Accurate statistics are vital for the query optimizer to generate efficient and reliable query execution plans. Without accurate and updated statistics, the performance of your SQL Server would likely suffer. For more information about this Dynamic Management Function, please see the below Books Online link: http://msdn.microsoft.com/en-us/library/jj553546.aspx Folllow me on Twitter @PrimeTimeDBA

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  • Logical and Physical Modeling for Analytical Applications

    - by Dejan Sarka
    I am proud to announce that my first course for Pluralsight is released. The course title is Logical and Physical Modeling for Analytical Applications. Here is the description of the course. A bad data model leads to an application that does not perform well. Therefore, when developing an application, you should create a good data model from the start. However, even the best logical model can’t help when the physical implementation is bad. It is also important to know how SQL Server stores and accesses data, and how to optimize the data access. Database optimization starts by splitting transactional and analytical applications. In this course, you learn how to support analytical applications with logical design, get understanding of the problems with data access for queries that deal with large amounts of data, and learn about SQL Server optimizations that help solving these problems. Enjoy the course!

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  • Online Password Security Tactics

    - by BuckWoody
    Recently two more large databases were attacked and compromised, one at the popular Gawker Media sites and the other at McDonald’s. Every time this kind of thing happens (which is FAR too often) it should remind the technical professional to ensure that they secure their systems correctly. If you write software that stores passwords, it should be heavily encrypted, and not human-readable in any storage. I advocate a different store for the login and password, so that if one is compromised, the other is not. I also advocate that you set a bit flag when a user changes their password, and send out a reminder to change passwords if that bit isn’t changed every three or six months.    But this post is about the *other* side – what to do to secure your own passwords, especially those you use online, either in a cloud service or at a provider. While you’re not in control of these breaches, there are some things you can do to help protect yourself. Most of these are obvious, but they contain a few little twists that make the process easier.   Use Complex Passwords This is easily stated, and probably one of the most un-heeded piece of advice. There are three main concepts here: ·         Don’t use a dictionary-based word ·         Use mixed case ·         Use punctuation, special characters and so on   So this: password Isn’t nearly as safe as this: P@ssw03d   Of course, this only helps if the site that stores your password encrypts it. Gawker does, so theoretically if you had the second password you’re in better shape, at least, than the first. Dictionary words are quickly broken, regardless of the encryption, so the more unusual characters you use, and the farther away from the dictionary words you get, the better.   Of course, this doesn’t help, not even a little, if the site stores the passwords in clear text, or the key to their encryption is broken. In that case…   Use a Different Password at Every Site What? I have hundreds of sites! Are you kidding me? Nope – I’m not. If you use the same password at every site, when a site gets attacked, the attacker will store your name and password value for attacks at other sites. So the only safe thing to do is to use different names or passwords (or both) at each site. Of course, most sites use your e-mail as a username, so you’re kind of hosed there. So even though you have hundreds of sites you visit, you need to have at least a different password at each site.   But it’s easier than you think – if you use an algorithm.   What I’m describing is to pick a “root” password, and then modify that based on the site or purpose. That way, if the site is compromised, you can still use that root password for the other sites.   Let’s take that second password: P@ssw03d   And now you can append, prepend or intersperse that password with other characters to make it unique to the site. That way you can easily remember the root password, but make it unique to the site. For instance, perhaps you read a lot of information on Gawker – how about these:   P@ssw03dRead ReadP@ssw03d PR@esasdw03d   If you have lots of sites, tracking even this can be difficult, so I recommend you use password software such as Password Safe or some other tool to have a secure database of your passwords at each site. DO NOT store this on the web. DO NOT use an Office document (Microsoft or otherwise) that is “encrypted” – the encryption office automation packages use is very trivial, and easily broken. A quick web search for tools to do that should show you how bad a choice this is.   Change Your Password on a Schedule I know. It’s a real pain. And it doesn’t seem worth it…until your account gets hacked. A quick note here – whenever a site gets hacked (and I find out about it) I change the password at that site immediately (or quit doing business with them) and then change the root password on every site, as quickly as I can.   If you follow the tip above, it’s not as hard. Just add another number, year, month, day, something like that into the mix. It’s not unlike making a Primary Key in an RDBMS.   P@ssw03dRead10242010   Change the site, and then update your password database. I do this about once a month, on the first or last day, during staff meetings. (J)   If you have other tips, post them here. We can all learn from each other on this.

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  • I Could Sure Use Some Windows Azure Code Samples…

    - by BuckWoody
    There are multiple ways to learn, and one of the most effective is with examples. You have multiple options with Windows Azure, including the Software Development Kit, the Windows Azure Training Kit and now another one…. the Microsoft All-In-One Code Framework,, a free, centralized code sample library driven by developers' real-world pains and needs. The goal is to provide customer-driven code samples for all Microsoft development technologies, and Windows Azure is included. Once you hit the site, you download an EXE that will create a web-app based installer for a Code Browser.   Once inside, you can configure where the samples store data and other settings, and then search for what you want.   You can also request a sample – if enough people ask, we do it. OneCode also partnered with gallery and Visual Studio team to develop this Sample Browser Visual Studio extension.  It’s an easy way for developers to find and download samples from within Visual Studio.  

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  • top tweets SOA Partner Community – June 2013

    - by JuergenKress
    Send your tweets @soacommunity #soacommunity and follow us at http://twitter.com/soacommunity Oracle SOA Learn how Business Rules are used in Oracle SOA Suite. New free self-study course - Oracle Univ. #soa #oraclesoa http://pub.vitrue.com/ll9B OPITZ CONSULTING ?Wie #BPM und #SOA zusammengehören? Watch 100-Seconds-Video-Lesson by @Rolfbaer - http://ow.ly/luSjK @soacommunity Andrejus Baranovskis ?Customized BPM 11g PS6 Workspace Application http://fb.me/2ukaSBXKs Mark Nelson ?Case Management Samples Released http://wp.me/pgVeO-Lv Mark Nelson Instance Patching Demo for BPM 11.1.1.7 http://wp.me/pgVeO-Lx Simone Geib Antony Reynolds: Target Verification #oraclesoa https://blogs.oracle.com/reynolds/ OPITZ CONSULTING ?"It's all about Integration - Developing with Oracle #Cloud Services" @t_winterberg files: http://ow.ly/ljtEY #cloudworld @soacommunity Arun Pareek ?Functional Testing Business Processes In Oracle BPM Suite 11g http://wp.me/pkPu1-pc via @arrunpareek SOA Proactive Want to get started with Human Workflow? Check out the introductory video on OTN, http://pub.vitrue.com/enIL C2B2 Consulting Free tech workshop,London 6th of Jun Diagnosing Performance & Scalability Problems in Oracle SOASuite http://www.c2b2.co.uk/oracle_fusion_middleware_performance_seminar … @soacommunity Oracle BPM Must have technologies for delivering effective #CX : #BPM #Social #Mobile > #OracleBPM Whitepaper http://pub.vitrue.com/6pF6 OracleBlogs ?Introduction to Web Forms -Basic Tutorial http://ow.ly/2wQLTE OTNArchBeat ?Complete State of SOA podcast now available w/ @soacommunity @hajonormann @gschmutz @t_winterberg #industrialsoa http://pub.vitrue.com/PZFw Ronald Luttikhuizen VENNSTER Blog | Article published - Fault Handling and Prevention - Part 2 | http://blog.vennster.nl/2013/05/article-published-fault-handling-and.html … Mark Nelson ?Getting to know Maven http://wp.me/pgVeO-Lk gschmutz ?Cool! Our 2nd article has just been published: "Fault Handling and Prevention for Services in Oracle Service Bus" http://pub.vitrue.com/jMOy David Shaffer Interesting SOA Development and Delivery post on A-Team Redstack site - http://bit.ly/18oqrAI . Would be great to get others to contribute! Mark Nelson BPM PS6 video showing process lifecycle in more detail (30min) http://wp.me/pgVeO-Ko SOA Proactive ?Webcast: 'Introduction and Troubleshooting of the SOA 11g Database Adapter', May 9th. Register now at http://pub.vitrue.com/8In7 Mark Nelson ?SOA Development and Delivery http://wp.me/pgVeO-Kd Oracle BPM Manoj Das, VP Product Mangement talks about new #OracleBPM release #BPM #processmanagement http://pub.vitrue.com/FV3R OTNArchBeat Podcast: The State of SOA w/ @soacommunity @hajonormann @gschmutz @t_winterberg #industrialsoa http://pub.vitrue.com/OK2M gschmutz New article series on Industrial SOA started on OTN and Service Technology Magazine: http://guidoschmutz.wordpress.com/2013/04/22/first-two-chapters-of-industrial-soa-articles-series-have-been-published-both-on-otn-and-service-technology-magazine/ … #industrialSOA Danilo Schmiedel ?Article series #industrialSOA published on OTN and Service Technology Magazine http://inside-bpm-and-soa.blogspot.de/2013/04/industrial-soa_22.html … @soacommunity @OC_WIRE SOA & BPM Partner Community For regular information on Oracle SOA Suite become a member in the SOA & BPM Partner Community for registration please visit www.oracle.com/goto/emea/soa (OPN account required) If you need support with your account please contact the Oracle Partner Business Center. Blog Twitter LinkedIn Facebook Wiki Mix Forum Technorati Tags: twitter,SOA Community,Oracle SOA,Oracle BPM,Community,OPN,Jürgen Kress

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  • Survey: How much data do you work with?

    - by James Luetkehoelter
    Andy isn't the only one that can ask a survey question. This is something I really curious about because many of the answers or recommendations or rants in blogs are not universably applicable to every database - small databases must sometimes be treated differently, and uber databases are just a pain (and fun at the same time). So, how would you classify most of the databases you work with: 1) Up to 50GB 2) 50-500GB 3) 500GB - 2TB 4) DEAR GOD THAT"S TOO MUCH INFORMATION! Share this post: email it!...(read more)

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  • SQL SERVER – Weekly Series – Memory Lane – #006

    - by pinaldave
    Here is the list of selected articles of SQLAuthority.com across all these years. Instead of just listing all the articles I have selected a few of my most favorite articles and have listed them here with additional notes below it. Let me know which one of the following is your favorite article from memory lane. 2006 This was my very first year of blogging so I was every day learning something new. As I have said many times, that blogging was never an intention. I had really not understood what exactly I am working on or beginning when I was beginning blogging in 2006. I had never knew that my life was going to change forever, once I started blogging. When I look back all of this year, I am happy that we are here together. 2007 IT Outsourcing to India – Top 10 Reasons Companies Outsource Outsourcing is about trust, collaboration and success. Helping other countries in need has been always the course of mankind, outsourcing is nothing different then that. With information technology and process improvements increasing the complexity, costs and skills required to accomplish routine tasks as well as challenging complex tasks, companies are outsourcing such tasks to providers who have the expertise to perform them at lower costs , with greater value and quality outcome. UDF – Remove Duplicate Chars From String This was a very interesting function I wrote in my early career. I am still using this function when I have to remove duplicate chars from strings. I have yet to come across a scenario where it does not work so I keep on using it till today. Please leave a comment if there is any better solution to this problem. FIX : Error : 3702 Cannot drop database because it is currently in use This is a very generic error when DROP Database is command is executed and the database is not dropped. The common mistake user is kept the connection open with this database and trying to drop the database. The database cannot be dropped if there is any other connection open along with it. It is always a good idea to take database in single user mode before dropping it. Here is the quick tutorial regarding how to bring the database in single user mode: Using T-SQL | Using SSMS. 2008 Install SQL Server 2008 – How to Upgrade to SQL Server 2008 – Installation Tutorial This was indeed one of the most popular articles in SQL Server 2008. Lots of people wanted to learn how to install SQL SErver 2008 but they were facing various issues while installation. I build this tutorial which becomes reference points for many. Default Collation of SQL Server 2008 What is the collation of SQL Server 2008 default installations? I often see this question confusing many experienced developers as well. Well the answer is in following image. Ahmedabad SQL Server User Group Meeting – November 2008 User group meetings are fun, now a days I am going to User Group meetings every week but there was a case when I have been just a beginner on this subject. The bug of the community was caught on me years ago when I started to present in Ahmedabad and Gandhinagar SQ LServer User Groups. 2009 Validate an XML document in TSQL using XSD My friend Jacob Sebastian wrote an excellent article on the subject XML and XSD. Because of the ‘eXtensible’ nature of XML (eXtensible Markup Language), often there is a requirement to restrict and validate the content of an XML document to a pre-defined structure and values. XSD (XML Schema Definition Language) is the W3C recommended language for describing and validating XML documents. SQL Server implements XSD as XML Schema Collections. Star Join Query Optimization At present, when queries are sent to very large databases, millions of rows are returned. Also the users have to go through extended query response times when joining multiple tables are involved with such queries. ‘Star Join Query Optimization’ is a new feature of SQL Server 2008 Enterprise Edition. This mechanism uses bitmap filtering for improving the performance of some types of queries by the effective retrieval of rows from fact tables. 2010 These puzzles are very interesting and intriguing – there was lots of interest on this subject. If you have free time this weekend. You may want to try them out. SQL SERVER – Challenge – Puzzle – Usage of FAST Hint (Solution)  SQL SERVER – Puzzle – Challenge – Error While Converting Money to Decimal (Solution)  SQL SERVER – Challenge – Puzzle – Why does RIGHT JOIN Exists (Open)  Additionally, I had great fun presenting SQL Server Performance Tuning seminar at fantastic locations in Hyderabad. Installing AdventeWorks Database This has been the most popular request I have received on my blog. Here is the quick video about how one can install AdventureWorks. 2011 Effect of SET NOCOUNT on @@ROWCOUNT There was an interesting incident once while I was presenting a session. I wrote a code and suddenly 10 hands went up in the air.  This was a bit surprise to me as I do not know why they all got alerted. I assumed that there should be something wrong with either project, screen or my display. However the real reason was very interesting – I suggest you read the complete blog post to understand this interesting scenario. Error: Deleting Offline Database and Creating the Same Name This is very interesting because once a user deletes the offline database the MDF and LDF file still exists and if the user attempts to create a new database with the same name it will give error. I found this very interesting and the blog explains the concept very quickly. Have you ever faced a similar situation? Reference: Pinal Dave (http://blog.sqlauthority.com) Filed under: Memory Lane, PostADay, SQL, SQL Authority, SQL Query, SQL Server, SQL Tips and Tricks, T SQL, Technology

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  • Smart defaults [SSDT]

    - by jamiet
    I’ve just discovered a new, somewhat hidden, feature in SSDT that I didn’t know about and figured it would be worth highlighting here because I’ll bet not many others know it either; the feature is called Smart Defaults. It gets around the problem of adding a NOT NULLable column to an existing table that has got data in it – previous to SSDT you would need to define a DEFAULT constraint however it does feel rather cumbersome to create an object purely for the purpose of pushing through a deployment – that’s the situation that Smart Defaults is meant to alleviate. The Smart Defaults option exists in the advanced section of a Publish Profile file: The description of the setting is “Automatically provides a default value when updating a table that contains data with a column that does not allow null values”, in other words checking that option will cause SSDT to insert an arbitrary default value into your newly created NON NULLable column. In case you’re wondering how it does it, here’s how: SSDT creates a DEFAULT CONSTRAINT at the same time as the column is created and then immediately removes that constraint: ALTER TABLE [dbo].[T1]    ADD [C1] INT NOT NULL,         CONSTRAINT [SD_T1_1df7a5f76cf44bb593506d05ff9a1e2b] DEFAULT 0 FOR [C1];ALTER TABLE [dbo].[T1] DROP CONSTRAINT [SD_T1_1df7a5f76cf44bb593506d05ff9a1e2b]; You can then update the value as appropriate in a Post-Deployment script. Pretty cool! On the downside, you can only specify this option for the whole project, not for an individual table or even an individual column – I’m not sure that I’d want to turn this on for an entire project as it could hide problems that a failed deployment would highlight, in other words smart defaults could be seen to be “papering over the cracks”. If you think that should be improved go and vote (and leave a comment) at [SSDT] Allow us to specify Smart defaults per table or even per column. @Jamiet

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  • Converting #MDX to #DAX and PowerPivot Workshop online #ppws

    - by Marco Russo (SQLBI)
    I just published the article Converting MDX to DAX – First Steps on the renewed SQLBI web site about converting MDX to DAX. The reason is that with BISM Tabular in Analysis Services 2012 you will be able to write queries in both DAX and MDX. If you already know MDX, you might wonder how to “translate” your MDX knowledge in DAX. I think that this is another way you can improve your knowledge about DAX: it has different concepts behind and this comparison should be helpful in this purpose. This is...(read more)

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  • Women in Technology Microsoft Career Webcast: Learn More About Microsoft Services Roles

    - by Lara Rubbelke
    Since I joined Microsoft over 2 1/2 years ago, many of my friends and colleagues ask me how I like it and how things are going. To be more precise, often these friends tip their heads to the side and ask with great concern “How are you doing? Are you working all the time?”. In many cases, I think this would be the same manner that they may have inquired on my state after a death in the family:-) I don’t begrudge anyone for how they approach me in my choice to join Microsoft, and fully appreciate...(read more)

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  • SQL SERVER – Download FREE PDFs from SQLAuthority.com

    - by Pinal Dave
    Throughout the last seven years, we have created many PDF downloads from SQLAuthority.com and many are very much appreciated by users. I just wanted to list all the downloads which we have created so far in a single place, hence here is the blog post which contains all the PDF downloads which we have created so far. SQL Server Interview Questions and Answers Download Beginning Big Data with NuoDB SQL Server Management Studio Keyboard Shorts Download SQL Server 2008 Certification Path Complete Download SQL Server Cheat Sheet Download SQL Server Database Coding Standards and Guidelines Complete List Download SQL Server Indexing Checklist Let me know which one of the PDF you like the most and if you expect us to create any more PDF articles. Leave a comment. Additionally, we have created various script bank for all the script which has been used on SQLAuthority.com so far. You can get access to the scripts by clicking on following link. SQLAuthority.com Scripts Download Reference : Pinal Dave (http://blog.SQLAuthority.com) Filed under: PostADay, SQL, SQL Authority, SQL Download, SQL Query, SQL Server, SQL Tips and Tricks, T SQL

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  • Open the SQL Server Error Log with PowerShell

    - by BuckWoody
    Using the Server Management Objects (SMO) library, you don’t even need to have the SQL Server 2008 PowerShell Provider to read the SQL Server Error Logs – in fact, you can use regular old everyday PowerShell. Keep in mind you will need the SMO libraries – which can be installed separately or by installing the Client Tools from the SQL Server install media. You could search for errors, store a result as a variable, or act on the returned values in some other way. Replace the Machine Name with your server and Instance Name with your instance, but leave the quotes, to make this work on your system: [reflection.assembly]::LoadWithPartialName("Microsoft.SqlServer.Smo") $machineName = "UNIVAC" $instanceName = "Production" $sqlServer = new-object ("Microsoft.SqlServer.Management.Smo.Server") "$machineName\$instanceName" $sqlServer.ReadErrorLog() Want to search for something specific, like the word “Error”? Replace the last line with this: $sqlServer.ReadErrorLog() | where {$_.Text -like "Error*"} Script Disclaimer, for people who need to be told this sort of thing: Never trust any script, including those that you find here, until you understand exactly what it does and how it will act on your systems. Always check the script on a test system or Virtual Machine, not a production system. Yes, there are always multiple ways to do things, and this script may not work in every situation, for everything. It’s just a script, people. All scripts on this site are performed by a professional stunt driver on a closed course. Your mileage may vary. Void where prohibited. Offer good for a limited time only. Keep out of reach of small children. Do not operate heavy machinery while using this script. If you experience blurry vision, indigestion or diarrhea during the operation of this script, see a physician immediately. Share this post: email it! | bookmark it! | digg it! | reddit! | kick it! | live it!

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  • Blogger sub-directory

    - by user137263
    There has long been a debate on the internet about SEO in relation to using either sub-domains or sub-directories for blogs. I am not terribly interested in that debate. I merely want to redirect my blogger blog to my domain, the easiest way possible, and in a manner least likely to impair the current functionality of my server/websites. I believe that the simplest way in which to do this is to use a subdirectory for the blog (although I am slightly concerned that the CNAME record will be shared by both) My question is this: how to use custom domain sub-directories when blogger refuse their use; complaining that the "URL must not end with a path" when a user attempts to establish such a custom domain? Google searches on this matter are oddly useless, as most results return Blogger's forum entries that always seem to direct to Blogger's Help home page o.O (using the search facilities of Blogger's Help directory itself fails to unearth these forum posts). Any pointers (no pun intended) would be greatly appreciated.

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  • Time for the yearly Microsoft Pilgrimage known as the MVP Summit

    - by drsql
    One of the most fun events of the year is the MVP Summit if perhaps for no other reason than my preparation for it is packing a suitcase. No presentations to write, prepare for, nothing. No activities that I have to do anything more than show up with my 2 shovels. One for the amazing amounts of knowledge that will be flowing from the Microsoft folks to us, and the other is actually more of a fork, to get all of the great food they serve us in with.  The whole event is a lot like any other conference,...(read more)

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  • Spooling in SQL execution plans

    - by Rob Farley
    Sewing has never been my thing. I barely even know the terminology, and when discussing this with American friends, I even found out that half the words that Americans use are different to the words that English and Australian people use. That said – let’s talk about spools! In particular, the Spool operators that you find in some SQL execution plans. This post is for T-SQL Tuesday, hosted this month by me! I’ve chosen to write about spools because they seem to get a bad rap (even in my song I used the line “There’s spooling from a CTE, they’ve got recursion needlessly”). I figured it was worth covering some of what spools are about, and hopefully explain why they are remarkably necessary, and generally very useful. If you have a look at the Books Online page about Plan Operators, at http://msdn.microsoft.com/en-us/library/ms191158.aspx, and do a search for the word ‘spool’, you’ll notice it says there are 46 matches. 46! Yeah, that’s what I thought too... Spooling is mentioned in several operators: Eager Spool, Lazy Spool, Index Spool (sometimes called a Nonclustered Index Spool), Row Count Spool, Spool, Table Spool, and Window Spool (oh, and Cache, which is a special kind of spool for a single row, but as it isn’t used in SQL 2012, I won’t describe it any further here). Spool, Table Spool, Index Spool, Window Spool and Row Count Spool are all physical operators, whereas Eager Spool and Lazy Spool are logical operators, describing the way that the other spools work. For example, you might see a Table Spool which is either Eager or Lazy. A Window Spool can actually act as both, as I’ll mention in a moment. In sewing, cotton is put onto a spool to make it more useful. You might buy it in bulk on a cone, but if you’re going to be using a sewing machine, then you quite probably want to have it on a spool or bobbin, which allows it to be used in a more effective way. This is the picture that I want you to think about in relation to your data. I’m sure you use spools every time you use your sewing machine. I know I do. I can’t think of a time when I’ve got out my sewing machine to do some sewing and haven’t used a spool. However, I often run SQL queries that don’t use spools. You see, the data that is consumed by my query is typically in a useful state without a spool. It’s like I can just sew with my cotton despite it not being on a spool! Many of my favourite features in T-SQL do like to use spools though. This looks like a very similar query to before, but includes an OVER clause to return a column telling me the number of rows in my data set. I’ll describe what’s going on in a few paragraphs’ time. So what does a Spool operator actually do? The spool operator consumes a set of data, and stores it in a temporary structure, in the tempdb database. This structure is typically either a Table (ie, a heap), or an Index (ie, a b-tree). If no data is actually needed from it, then it could also be a Row Count spool, which only stores the number of rows that the spool operator consumes. A Window Spool is another option if the data being consumed is tightly linked to windows of data, such as when the ROWS/RANGE clause of the OVER clause is being used. You could maybe think about the type of spool being like whether the cotton is going onto a small bobbin to fit in the base of the sewing machine, or whether it’s a larger spool for the top. A Table or Index Spool is either Eager or Lazy in nature. Eager and Lazy are Logical operators, which talk more about the behaviour, rather than the physical operation. If I’m sewing, I can either be all enthusiastic and get all my cotton onto the spool before I start, or I can do it as I need it. “Lazy” might not the be the best word to describe a person – in the SQL world it describes the idea of either fetching all the rows to build up the whole spool when the operator is called (Eager), or populating the spool only as it’s needed (Lazy). Window Spools are both physical and logical. They’re eager on a per-window basis, but lazy between windows. And when is it needed? The way I see it, spools are needed for two reasons. 1 – When data is going to be needed AGAIN. 2 – When data needs to be kept away from the original source. If you’re someone that writes long stored procedures, you are probably quite aware of the second scenario. I see plenty of stored procedures being written this way – where the query writer populates a temporary table, so that they can make updates to it without risking the original table. SQL does this too. Imagine I’m updating my contact list, and some of my changes move data to later in the book. If I’m not careful, I might update the same row a second time (or even enter an infinite loop, updating it over and over). A spool can make sure that I don’t, by using a copy of the data. This problem is known as the Halloween Effect (not because it’s spooky, but because it was discovered in late October one year). As I’m sure you can imagine, the kind of spool you’d need to protect against the Halloween Effect would be eager, because if you’re only handling one row at a time, then you’re not providing the protection... An eager spool will block the flow of data, waiting until it has fetched all the data before serving it up to the operator that called it. In the query below I’m forcing the Query Optimizer to use an index which would be upset if the Name column values got changed, and we see that before any data is fetched, a spool is created to load the data into. This doesn’t stop the index being maintained, but it does mean that the index is protected from the changes that are being done. There are plenty of times, though, when you need data repeatedly. Consider the query I put above. A simple join, but then counting the number of rows that came through. The way that this has executed (be it ideal or not), is to ask that a Table Spool be populated. That’s the Table Spool operator on the top row. That spool can produce the same set of rows repeatedly. This is the behaviour that we see in the bottom half of the plan. In the bottom half of the plan, we see that the a join is being done between the rows that are being sourced from the spool – one being aggregated and one not – producing the columns that we need for the query. Table v Index When considering whether to use a Table Spool or an Index Spool, the question that the Query Optimizer needs to answer is whether there is sufficient benefit to storing the data in a b-tree. The idea of having data in indexes is great, but of course there is a cost to maintaining them. Here we’re creating a temporary structure for data, and there is a cost associated with populating each row into its correct position according to a b-tree, as opposed to simply adding it to the end of the list of rows in a heap. Using a b-tree could even result in page-splits as the b-tree is populated, so there had better be a reason to use that kind of structure. That all depends on how the data is going to be used in other parts of the plan. If you’ve ever thought that you could use a temporary index for a particular query, well this is it – and the Query Optimizer can do that if it thinks it’s worthwhile. It’s worth noting that just because a Spool is populated using an Index Spool, it can still be fetched using a Table Spool. The details about whether or not a Spool used as a source shows as a Table Spool or an Index Spool is more about whether a Seek predicate is used, rather than on the underlying structure. Recursive CTE I’ve already shown you an example of spooling when the OVER clause is used. You might see them being used whenever you have data that is needed multiple times, and CTEs are quite common here. With the definition of a set of data described in a CTE, if the query writer is leveraging this by referring to the CTE multiple times, and there’s no simplification to be leveraged, a spool could theoretically be used to avoid reapplying the CTE’s logic. Annoyingly, this doesn’t happen. Consider this query, which really looks like it’s using the same data twice. I’m creating a set of data (which is completely deterministic, by the way), and then joining it back to itself. There seems to be no reason why it shouldn’t use a spool for the set described by the CTE, but it doesn’t. On the other hand, if we don’t pull as many columns back, we might see a very different plan. You see, CTEs, like all sub-queries, are simplified out to figure out the best way of executing the whole query. My example is somewhat contrived, and although there are plenty of cases when it’s nice to give the Query Optimizer hints about how to execute queries, it usually doesn’t do a bad job, even without spooling (and you can always use a temporary table). When recursion is used, though, spooling should be expected. Consider what we’re asking for in a recursive CTE. We’re telling the system to construct a set of data using an initial query, and then use set as a source for another query, piping this back into the same set and back around. It’s very much a spool. The analogy of cotton is long gone here, as the idea of having a continual loop of cotton feeding onto a spool and off again doesn’t quite fit, but that’s what we have here. Data is being fed onto the spool, and getting pulled out a second time when the spool is used as a source. (This query is running on AdventureWorks, which has a ManagerID column in HumanResources.Employee, not AdventureWorks2012) The Index Spool operator is sucking rows into it – lazily. It has to be lazy, because at the start, there’s only one row to be had. However, as rows get populated onto the spool, the Table Spool operator on the right can return rows when asked, ending up with more rows (potentially) getting back onto the spool, ready for the next round. (The Assert operator is merely checking to see if we’ve reached the MAXRECURSION point – it vanishes if you use OPTION (MAXRECURSION 0), which you can try yourself if you like). Spools are useful. Don’t lose sight of that. Every time you use temporary tables or table variables in a stored procedure, you’re essentially doing the same – don’t get upset at the Query Optimizer for doing so, even if you think the spool looks like an expensive part of the query. I hope you’re enjoying this T-SQL Tuesday. Why not head over to my post that is hosting it this month to read about some other plan operators? At some point I’ll write a summary post – once I have you should find a comment below pointing at it. @rob_farley

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  • SQL Saturday 47 Phoenix February 2011

    - by billramo
    Today I presented data collection strategies for SQL Server 2008 at Phoenix SQL Saturday 47. I’ve attached my deck to this post so that you can get the links and references that I presented. To learn more about the Data Collector, check out these links. SQL Server 2008 Data Collector Proof of Concept – How to get started with Data Collector in your organization SQL Server Query Hash Statistics – Replacement for the shipping Query Statistics collection set Writing Reports Against the Management Data Warehouse – This is part 1 of the series on MDW reports. You can see all the articles through this link. Be sure to click on the attachment link to download the slides.

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  • New SSIS features and enhancements in Denali – a webinar on 28th June in association with Pragmatic Works

    - by jamiet
    Tomorrow I shall be presenting a webinar entitled “New SSIS features and enhancements in Denali”. The webinar is being hosted by Pragmatic Works and you can sign up for it at Pragmatic Works webinars. The webinar will start at 1930BST and you can view the time for your timezone at this link: http://www.timeanddate.com/worldclock/fixedtime.html?msg=New+SSIS+features+and+enhancements+in+Denali&iso=20110628T1830 The webinar was arranged a few months ago and at that time we were hoping that the next Community Technology Preview (CTP) of SQL Server Denali would be available for public consumption; unfortunately it transpires that that is not yet the case and hence I will be presenting new features of CTP1 that was released at the start of this year. If you’re not yet familiar with the new features of SSIS that are coming in the next release of SQL Server then please do come and join the webinar. @Jamiet

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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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  • The final Cumulative Update for SQL Server 2008 SP3

    - by AaronBertrand
    Microsoft has released the final Cumulative Update (#17) for SQL Server 2008 Service Pack 3. Build # 10.00.5861 KB Article: KB #2958696 9 public fixes Relevant for builds 10.00.5500 -> 10.00.5860 NOT for SQL Server 2008 R2 (10.50.xxxx) Once more, this is the last cumulative update for SQL Server 2008. Both 2008 and 2008 R2 exit mainstream support in July of this year. That's two months away. If you want a final service pack for either or both of these major versions, and want your voice heard,...(read more)

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  • Survey: How do you manage the source code for your personal projects?

    - by Linchi Shea
    This seems to be the survey season. Andy’s post on source controlling T-SQL code triggered a question that I always wanted to ask. Do you version control the source code for your various personal projects (i.e. not projects of your customer or employer)? Do you use a computer at home for your source control repository, or do you use a hosting service such as ProjectLocker ? If you do it yourself at home, what version control software you use? If you use a hosting service, what’s your experience?...(read more)

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  • SQL File Layout Viewer 1.2

    - by merrillaldrich
    Just ahead of presenting it at SQL Saturday in my home town of Minneapolis / Saint Paul, I’m happy to release an updated version of the SQL Server File Layout Viewer. This is a utility I released back in March for inspecting the arrangement of data pages in SQL Server files. If you will be in Minneapolis this Saturday (space permitting), please come out and see this tool in action! New Features Based on feedback from others in the SQL Server community, I made these enhancements: Page types now provide...(read more)

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  • SQL Server 2012 : A couple of notes about installing RC0

    - by AaronBertrand
    If you're going to install Distributed Replay Controller I've posted about this on twitter a few times, but I thought I should put it down somewhere permanent as well. When you install RC0, and have selected the Distributed Replay Controller, you should be very careful about choosing the "Add Current User" button on the following dialog (I felt compelled to embellish with the skull and crossbones): If you click this button (it may also happen for the Add... button), you may experience a little delay...(read more)

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  • Seeking on a Heap, and Two Useful DMVs

    - by Paul White
    So far in this mini-series on seeks and scans, we have seen that a simple ‘seek’ operation can be much more complex than it first appears.  A seek can contain one or more seek predicates – each of which can either identify at most one row in a unique index (a singleton lookup) or a range of values (a range scan).  When looking at a query plan, we will often need to look at the details of the seek operator in the Properties window to see how many operations it is performing, and what type of operation each one is.  As you saw in the first post in this series, the number of hidden seeking operations can have an appreciable impact on performance. Measuring Seeks and Scans I mentioned in my last post that there is no way to tell from a graphical query plan whether you are seeing a singleton lookup or a range scan.  You can work it out – if you happen to know that the index is defined as unique and the seek predicate is an equality comparison, but there’s no separate property that says ‘singleton lookup’ or ‘range scan’.  This is a shame, and if I had my way, the query plan would show different icons for range scans and singleton lookups – perhaps also indicating whether the operation was one or more of those operations underneath the covers. In light of all that, you might be wondering if there is another way to measure how many seeks of either type are occurring in your system, or for a particular query.  As is often the case, the answer is yes – we can use a couple of dynamic management views (DMVs): sys.dm_db_index_usage_stats and sys.dm_db_index_operational_stats. Index Usage Stats The index usage stats DMV contains counts of index operations from the perspective of the Query Executor (QE) – the SQL Server component that is responsible for executing the query plan.  It has three columns that are of particular interest to us: user_seeks – the number of times an Index Seek operator appears in an executed plan user_scans – the number of times a Table Scan or Index Scan operator appears in an executed plan user_lookups – the number of times an RID or Key Lookup operator appears in an executed plan An operator is counted once per execution (generating an estimated plan does not affect the totals), so an Index Seek that executes 10,000 times in a single plan execution adds 1 to the count of user seeks.  Even less intuitively, an operator is also counted once per execution even if it is not executed at all.  I will show you a demonstration of each of these things later in this post. Index Operational Stats The index operational stats DMV contains counts of index and table operations from the perspective of the Storage Engine (SE).  It contains a wealth of interesting information, but the two columns of interest to us right now are: range_scan_count – the number of range scans (including unrestricted full scans) on a heap or index structure singleton_lookup_count – the number of singleton lookups in a heap or index structure This DMV counts each SE operation, so 10,000 singleton lookups will add 10,000 to the singleton lookup count column, and a table scan that is executed 5 times will add 5 to the range scan count. The Test Rig To explore the behaviour of seeks and scans in detail, we will need to create a test environment.  The scripts presented here are best run on SQL Server 2008 Developer Edition, but the majority of the tests will work just fine on SQL Server 2005.  A couple of tests use partitioning, but these will be skipped if you are not running an Enterprise-equivalent SKU.  Ok, first up we need a database: USE master; GO IF DB_ID('ScansAndSeeks') IS NOT NULL DROP DATABASE ScansAndSeeks; GO CREATE DATABASE ScansAndSeeks; GO USE ScansAndSeeks; GO ALTER DATABASE ScansAndSeeks SET ALLOW_SNAPSHOT_ISOLATION OFF ; ALTER DATABASE ScansAndSeeks SET AUTO_CLOSE OFF, AUTO_SHRINK OFF, AUTO_CREATE_STATISTICS OFF, AUTO_UPDATE_STATISTICS OFF, PARAMETERIZATION SIMPLE, READ_COMMITTED_SNAPSHOT OFF, RESTRICTED_USER ; Notice that several database options are set in particular ways to ensure we get meaningful and reproducible results from the DMVs.  In particular, the options to auto-create and update statistics are disabled.  There are also three stored procedures, the first of which creates a test table (which may or may not be partitioned).  The table is pretty much the same one we used yesterday: The table has 100 rows, and both the key_col and data columns contain the same values – the integers from 1 to 100 inclusive.  The table is a heap, with a non-clustered primary key on key_col, and a non-clustered non-unique index on the data column.  The only reason I have used a heap here, rather than a clustered table, is so I can demonstrate a seek on a heap later on.  The table has an extra column (not shown because I am too lazy to update the diagram from yesterday) called padding – a CHAR(100) column that just contains 100 spaces in every row.  It’s just there to discourage SQL Server from choosing table scan over an index + RID lookup in one of the tests. The first stored procedure is called ResetTest: CREATE PROCEDURE dbo.ResetTest @Partitioned BIT = 'false' AS BEGIN SET NOCOUNT ON ; IF OBJECT_ID(N'dbo.Example', N'U') IS NOT NULL BEGIN DROP TABLE dbo.Example; END ; -- Test table is a heap -- Non-clustered primary key on 'key_col' CREATE TABLE dbo.Example ( key_col INTEGER NOT NULL, data INTEGER NOT NULL, padding CHAR(100) NOT NULL DEFAULT SPACE(100), CONSTRAINT [PK dbo.Example key_col] PRIMARY KEY NONCLUSTERED (key_col) ) ; IF @Partitioned = 'true' BEGIN -- Enterprise, Trial, or Developer -- required for partitioning tests IF SERVERPROPERTY('EngineEdition') = 3 BEGIN EXECUTE (' DROP TABLE dbo.Example ; IF EXISTS ( SELECT 1 FROM sys.partition_schemes WHERE name = N''PS'' ) DROP PARTITION SCHEME PS ; IF EXISTS ( SELECT 1 FROM sys.partition_functions WHERE name = N''PF'' ) DROP PARTITION FUNCTION PF ; CREATE PARTITION FUNCTION PF (INTEGER) AS RANGE RIGHT FOR VALUES (20, 40, 60, 80, 100) ; CREATE PARTITION SCHEME PS AS PARTITION PF ALL TO ([PRIMARY]) ; CREATE TABLE dbo.Example ( key_col INTEGER NOT NULL, data INTEGER NOT NULL, padding CHAR(100) NOT NULL DEFAULT SPACE(100), CONSTRAINT [PK dbo.Example key_col] PRIMARY KEY NONCLUSTERED (key_col) ) ON PS (key_col); '); END ELSE BEGIN RAISERROR('Invalid SKU for partition test', 16, 1); RETURN; END; END ; -- Non-unique non-clustered index on the 'data' column CREATE NONCLUSTERED INDEX [IX dbo.Example data] ON dbo.Example (data) ; -- Add 100 rows INSERT dbo.Example WITH (TABLOCKX) ( key_col, data ) SELECT key_col = V.number, data = V.number FROM master.dbo.spt_values AS V WHERE V.[type] = N'P' AND V.number BETWEEN 1 AND 100 ; END; GO The second stored procedure, ShowStats, displays information from the Index Usage Stats and Index Operational Stats DMVs: CREATE PROCEDURE dbo.ShowStats @Partitioned BIT = 'false' AS BEGIN -- Index Usage Stats DMV (QE) SELECT index_name = ISNULL(I.name, I.type_desc), scans = IUS.user_scans, seeks = IUS.user_seeks, lookups = IUS.user_lookups FROM sys.dm_db_index_usage_stats AS IUS JOIN sys.indexes AS I ON I.object_id = IUS.object_id AND I.index_id = IUS.index_id WHERE IUS.database_id = DB_ID(N'ScansAndSeeks') AND IUS.object_id = OBJECT_ID(N'dbo.Example', N'U') ORDER BY I.index_id ; -- Index Operational Stats DMV (SE) IF @Partitioned = 'true' SELECT index_name = ISNULL(I.name, I.type_desc), partitions = COUNT(IOS.partition_number), range_scans = SUM(IOS.range_scan_count), single_lookups = SUM(IOS.singleton_lookup_count) FROM sys.dm_db_index_operational_stats ( DB_ID(N'ScansAndSeeks'), OBJECT_ID(N'dbo.Example', N'U'), NULL, NULL ) AS IOS JOIN sys.indexes AS I ON I.object_id = IOS.object_id AND I.index_id = IOS.index_id GROUP BY I.index_id, -- Key I.name, I.type_desc ORDER BY I.index_id; ELSE SELECT index_name = ISNULL(I.name, I.type_desc), range_scans = SUM(IOS.range_scan_count), single_lookups = SUM(IOS.singleton_lookup_count) FROM sys.dm_db_index_operational_stats ( DB_ID(N'ScansAndSeeks'), OBJECT_ID(N'dbo.Example', N'U'), NULL, NULL ) AS IOS JOIN sys.indexes AS I ON I.object_id = IOS.object_id AND I.index_id = IOS.index_id GROUP BY I.index_id, -- Key I.name, I.type_desc ORDER BY I.index_id; END; The final stored procedure, RunTest, executes a query written against the example table: CREATE PROCEDURE dbo.RunTest @SQL VARCHAR(8000), @Partitioned BIT = 'false' AS BEGIN -- No execution plan yet SET STATISTICS XML OFF ; -- Reset the test environment EXECUTE dbo.ResetTest @Partitioned ; -- Previous call will throw an error if a partitioned -- test was requested, but SKU does not support it IF @@ERROR = 0 BEGIN -- IO statistics and plan on SET STATISTICS XML, IO ON ; -- Test statement EXECUTE (@SQL) ; -- Plan and IO statistics off SET STATISTICS XML, IO OFF ; EXECUTE dbo.ShowStats @Partitioned; END; END; The Tests The first test is a simple scan of the heap table: EXECUTE dbo.RunTest @SQL = 'SELECT * FROM Example'; The top result set comes from the Index Usage Stats DMV, so it is the Query Executor’s (QE) view.  The lower result is from Index Operational Stats, which shows statistics derived from the actions taken by the Storage Engine (SE).  We see that QE performed 1 scan operation on the heap, and SE performed a single range scan.  Let’s try a single-value equality seek on a unique index next: EXECUTE dbo.RunTest @SQL = 'SELECT key_col FROM Example WHERE key_col = 32'; This time we see a single seek on the non-clustered primary key from QE, and one singleton lookup on the same index by the SE.  Now for a single-value seek on the non-unique non-clustered index: EXECUTE dbo.RunTest @SQL = 'SELECT data FROM Example WHERE data = 32'; QE shows a single seek on the non-clustered non-unique index, but SE shows a single range scan on that index – not the singleton lookup we saw in the previous test.  That makes sense because we know that only a single-value seek into a unique index is a singleton seek.  A single-value seek into a non-unique index might retrieve any number of rows, if you think about it.  The next query is equivalent to the IN list example seen in the first post in this series, but it is written using OR (just for variety, you understand): EXECUTE dbo.RunTest @SQL = 'SELECT data FROM Example WHERE data = 32 OR data = 33'; The plan looks the same, and there’s no difference in the stats recorded by QE, but the SE shows two range scans.  Again, these are range scans because we are looking for two values in the data column, which is covered by a non-unique index.  I’ve added a snippet from the Properties window to show that the query plan does show two seek predicates, not just one.  Now let’s rewrite the query using BETWEEN: EXECUTE dbo.RunTest @SQL = 'SELECT data FROM Example WHERE data BETWEEN 32 AND 33'; Notice the seek operator only has one predicate now – it’s just a single range scan from 32 to 33 in the index – as the SE output shows.  For the next test, we will look up four values in the key_col column: EXECUTE dbo.RunTest @SQL = 'SELECT key_col FROM Example WHERE key_col IN (2,4,6,8)'; Just a single seek on the PK from the Query Executor, but four singleton lookups reported by the Storage Engine – and four seek predicates in the Properties window.  On to a more complex example: EXECUTE dbo.RunTest @SQL = 'SELECT * FROM Example WITH (INDEX([PK dbo.Example key_col])) WHERE key_col BETWEEN 1 AND 8'; This time we are forcing use of the non-clustered primary key to return eight rows.  The index is not covering for this query, so the query plan includes an RID lookup into the heap to fetch the data and padding columns.  The QE reports a seek on the PK and a lookup on the heap.  The SE reports a single range scan on the PK (to find key_col values between 1 and 8), and eight singleton lookups on the heap.  Remember that a bookmark lookup (RID or Key) is a seek to a single value in a ‘unique index’ – it finds a row in the heap or cluster from a unique RID or clustering key – so that’s why lookups are always singleton lookups, not range scans. Our next example shows what happens when a query plan operator is not executed at all: EXECUTE dbo.RunTest @SQL = 'SELECT key_col FROM Example WHERE key_col = 8 AND @@TRANCOUNT < 0'; The Filter has a start-up predicate which is always false (if your @@TRANCOUNT is less than zero, call CSS immediately).  The index seek is never executed, but QE still records a single seek against the PK because the operator appears once in an executed plan.  The SE output shows no activity at all.  This next example is 2008 and above only, I’m afraid: EXECUTE dbo.RunTest @SQL = 'SELECT * FROM Example WHERE key_col BETWEEN 1 AND 30', @Partitioned = 'true'; This is the first example to use a partitioned table.  QE reports a single seek on the heap (yes – a seek on a heap), and the SE reports two range scans on the heap.  SQL Server knows (from the partitioning definition) that it only needs to look at partitions 1 and 2 to find all the rows where key_col is between 1 and 30 – the engine seeks to find the two partitions, and performs a range scan seek on each partition. The final example for today is another seek on a heap – try to work out the output of the query before running it! EXECUTE dbo.RunTest @SQL = 'SELECT TOP (2) WITH TIES * FROM Example WHERE key_col BETWEEN 1 AND 50 ORDER BY $PARTITION.PF(key_col) DESC', @Partitioned = 'true'; Notice the lack of an explicit Sort operator in the query plan to enforce the ORDER BY clause, and the backward range scan. © 2011 Paul White email: [email protected] twitter: @SQL_Kiwi

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