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  • SQLAuthority Book Review – Professional SQL Server 2008 Internals and Troubleshooting

    - by pinaldave
    Professional SQL Server 2008 Internals and Troubleshooting by Christian Bolton, Justin Langford, Brent Ozar, James Rowland-Jones, Steven Wort Link to Amazon (Worldwide) Link to Flipkart (India) Brief Review: Having a book on internal and associating that with real life is “almost” an impossible task. The reason for using the word “almost” is because this book has accomplished this [...]

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  • SQL SERVER – Recompile Stored Procedure at Run Time

    - by pinaldave
    I recently received an email from reader after reading my previous article on SQL SERVER – Plan Recompilation and Reduce Recompilation – Performance Tuning regarding how to recompile any stored procedure at run time. There are multiple ways to do this. If you want your stored procedure to always recompile at run time, you can add [...]

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  • SQLAuthority News – Keeping Your Ducks in a Row

    - by pinaldave
    Last year during my visit to SQLAuthority News – SQL PASS Summit, Seattle 2009 – Day 2 I have received ducks from the event. Well during the same event I had learned from Jonathan Kehayias the saying of ‘Keeping Your Ducks in a Row‘. The most popular theory suggests that “ducks in a row” came [...]

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  • SQL SERVER – Rollback TRUNCATE Command in Transaction

    - by pinaldave
    This is very common concept that truncate can not be rolled back. I always hear conversation between developer if truncate can be rolled back or not. If you use TRANSACTIONS in your code, TRUNCATE can be rolled back. If there is no transaction is used and TRUNCATE operation is committed, it can not be retrieved from [...]

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  • SQL SERVER – Transcript of Learning SQL Server Performance: Indexing Basics – Interview of Vinod Kumar by Pinal Dave

    - by pinaldave
    Recently I just wrote a blog post on about Learning SQL Server Performance: Indexing Basics and I received lots of request that if we can share some insight into the course. Here is 200 seconds interview of Vinod Kumar I took right after completing the course. We have few free codes to watch the course, please your comment at http://facebook.com/SQLAuth and we will few of first ones, we will send the code. There are many people who said they would like to read the transcript of the video. Here I have generated the same. Pinal: Vinod, we recently released this course, SQL Server Indexing. It is about performance tuning. So tell me – how do indexes help performance? Vinod: I think what happens in the industry when it comes to performance is that developers and DBAs look at indexes first.  So that’s the first step for any performance tuning exercise, indexing is one of the most critical aspects and it is important to learn it the right way. Pinal: Correct. So what you mean to say is that if you know indexing you can pretty much tune any server and query. Vinod: So I might contradict my false statement now. Indexing is usually a stepping stone but it does not lead you to the end. But it’s good to start with indexing and there are lots of nuances to indexing that you need to understand, like how SQL uses indexing and how performance can improve because of the strategies that you have made. Pinal: But now I’m confused. First you said indexes are good, and then you said that indexes can degrade your performance.  So what is this course about?  I mean how does this course really make an impact? Vinod: Ok -so from the course perspective, what we are trying to do is give you a capsule which gives you a good start. Every journey needs a beginning, you need that first step.  This course is that first step in understanding. This is the most basic, fundamental course that we have tried to attack. This is the fundamentals of indexing, some of the key things that you must know about indexing.   Some of the basics of indexing are lesser known and so I think this course is geared towards each and every one of you out there who wants to understand little bit more about indexing. Pinal: So what I understand is that if I enrolled in this course I will have a minimum understanding about indexing when dealing with performance tuning.  Right? Vinod: Exactly. In this course is we have tried to give you a nice summary. We are talking about clustered indexing, non clustered indexing, too many indexes, too few indexes, over indexing, under indexing, duplicate indexing, columns tune indexing, with SQL Server 2012. There’s lot’s to learn. Pinal: You can see the URL [http://bit.ly/sql-index] of the course on the screen. Go ahead, attend, and let us know what you think about it. Thank you. Vinod: Thank you. Reference: Pinal Dave (http://blog.sqlauthority.com) Filed under: PostADay, SQL, SQL Authority, SQL Index, SQL Performance, SQL Query, SQL Server, SQL Tips and Tricks, SQLServer, T SQL, Technology, Video

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  • #Error showing up in multiple LEFT JOIN statement Access query when value should be NULL

    - by lar
    I'm trying to return an ID's last 4 years of data, if existing. The table (call it A_TABLE) looks like this: ID, Year, Val The idea behind the query is this: for each ID/Year in the table, LEFT JOIN with Year-1, Year-2, and Year-3 (to get 4 years of data) and then return Val for each year. Here's the SQL: SELECT a.ID, a.year AS [Year], a.Val AS VAL, a1.year AS [Year-1], a1.Val AS [VAL-1], a2.year AS [Year-2], a2.Val AS [VAL-2], a3.year AS [Year-3], a3.Val AS [VAL-3] FROM ( ([A_TABLE] AS a LEFT JOIN [A_TABLE] AS a1 ON (a.ID = a1.ID) AND (a.year = a1.year+1)) LEFT JOIN [A_TABLE] AS a2 ON (a.ID = a2.ID) AND (a.year = a2.year+2)) LEFT JOIN [A_TABLE] AS a3 ON (a.ID = a3.ID) AND (a.year = a3.year+3) The problem is that, for past years where there is no data (eg, Year-1), I see "#Error" in the appropriate VAL column (eg, [VAL-1]). The weird thing is, I see the expected "null" in the Year column (eg, [YEAR-1]). Some sample data: ID YEAR VAL Dave 2004 1 Dave 2006 2 Dave 2007 3 Dave 2008 5 Dave 2009 0 outputs like this: ID YEAR VAL YEAR-1 VAL-1 YEAR-2 VAL-2 YEAR-3 VAL-3 Dave 2004 1 #Error #Error #Error Dave 2006 2 #Error 2004 1 #Error Dave 2007 3 2006 2 #Error 2004 1 Dave 2008 5 2007 3 2006 2 #Error Dave 2009 0 2008 5 2007 3 2006 2 Does that make sense? Why am I getting the appropriate NULL val for the non-existent YEARs, but an #Error for the non-existent VALs? (This is Access 2000. Conditional statements like "IIf(a1.val is null, -999, a1.val)" do not seem to do anything.) EDIT: It turns out that the errors are somehow caused by the fact that A_TABLE is actually a query. When I put all the data into an actual table and run the same query, everything shows up as it should. Thanks for the help, everyone.

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  • Javascript: Pass array as optional method args

    - by Dave Paroulek
    console.log takes a string and replaces tokens with values, for example: console.log("My name is %s, and I like %", 'Dave', 'Javascript') would print: My name is Dave, and I like Javascript I'd like to wrap this inside a method like so: function log(msg, values) { if(config.log == true){ console.log(msg, values); } } The 'values' arg might be a single value or several optional args. How can I accomplish this? If I call it like so: log("My name is %s, and I like %s", "Dave", "Javascript"); I get this (it doesn't recognize "Javascript" as a 3rd argument): My name is Dave, and I like %s If I call this: log("My name is %s, and I like %s", ["Dave", "Javascript"]); then it treats the second arg as an array (it doesn't expand to multiple args). What trick am I missing to get it to expand the optional args?

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  • Exchange Server 2007 Forwarding Circles

    - by LorenVS
    Hello, I asked a question quite a while ago about two members of an organization who wanted to receive all of each other's emails, and yet maintain seperate mailboxes. (so all emails to mike@company get sent to mike and dave and all emails to dave@company get sent to mike and dave). At the time, I actually only needed to implement one side of this (only mikes emails got sent to both receipients) and (with the help of ServerFault) I set up forwarding on dave's inbox so that all of his emails would also be sent to mike. I'm now in a situation where I have to implement the other side of this relation (such that mike's emails will also forward to dave). I still remember how to set up the forwarding rule, but I'm worried that I might be creating a circular forwarding rule such that mike@compnay forwards to dave@company which forwards to mike@company and so on. Can anyone clear up my confusion (just want to make sure I don't make a stupid mistake). Thanks a ton

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  • How to host multiple mail domains with courier?

    - by Dave Vogt
    I had my server set up with generic aliases in /etc/courier/aliases/users, which worked fine. But today I wanted to host some new domains, where addresses overlap. What I need is that [email protected] goes to account "dv", but [email protected] goes to account "d2". So I set up a new file containing fully qualified addresses ([email protected]: dv) instead of the previous dave: dv. But somehow, courier-smtpd doesn't accept mail to these addresses anymore. makealiases -dump prints all the aliases the way they should be.. so i'm a bit stuck.

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  • Figure out what non-symlink path would be?

    - by David Mackintosh
    On Linux, if I've cd'd around and am now in a directory, is there a way to figure out what the real path to that directory is if I had not used a symbolic link to get there? Consider: $ pwd /home/dave/tmp $ mkdir -p 1/2/3/4/5 $ ln -s 1/2/3/4/5 5 $ cd 5 $ pwd /home/dave/tmp/5 Or: $ pwd /home/dave/tmp $ mkdir -p 1/2/3/4/5 $ ln -s 1/2/3/4 4 $ cd 4/5 $ pwd /home/dave/tmp/4/5 Is there any way to figure out that /home/dave/tmp/5 is really /home/dave/1/2/3/4/5 ?

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  • Troubles with PyDev and external libraries in OS X

    - by Davide Gualano
    I've successfully installed the latest version of PyDev in my Eclipse (3.5.1) under OS X 10.6.3, with python 2.6.1 I have troubles in making the libraries I have installed work. For example, I'm trying to use the cx_Oracle library, which is perfectly working if called from the python interpeter of from simple scripts made with some text editor. But I cant make it work inside Eclipse: I have this small piece of code: import cx_Oracle conn = cx_Oracle.connect(CONN_STRING) sql = "select field from mytable" cursor = conn.cursor() cursor.execute(sql) for row in cursor: field = row[0] print field If I execute it from Eclipse, I get the following error: import cx_Oracle File "build/bdist.macosx-10.6-universal/egg/cx_Oracle.py", line 7, in <module> File "build/bdist.macosx-10.6-universal/egg/cx_Oracle.py", line 6, in __bootstrap__ ImportError: dlopen(/Users/dave/.python-eggs/cx_Oracle-5.0.3-py2.6-macosx-10.6-universal.egg-tmp/cx_Oracle.so, 2): Library not loaded: /b/227/rdbms/lib/libclntsh.dylib.10.1 Referenced from: /Users/dave/.python-eggs/cx_Oracle-5.0.3-py2.6-macosx-10.6-universal.egg-tmp/cx_Oracle.so Reason: no suitable image found. Did find: /Users/dave/lib/libclntsh.dylib.10.1: mach-o, but wrong architecture Same snippet works perfectly from the python shell I have configured the interpeter in Eclipse in preferences - PyDev -- Interpreter - Python, using the Auto Config option and selecting all the libs found. What am I doing wrong here? Edit: launching file /Users/dave/.python-eggs/cx_Oracle-5.0.3-py2.6-macosx-10.6-universal.egg-tmp/cx_Oracle.so from the command line tells this: /Users/dave/.python-eggs/cx_Oracle-5.0.3-py2.6-macosx-10.6-universal.egg-tmp/cx_Oracle.so: Mach-O universal binary with 3 architectures /Users/dave/.python-eggs/cx_Oracle-5.0.3-py2.6-macosx-10.6-universal.egg-tmp/cx_Oracle.so (for architecture i386): Mach-O bundle i386 /Users/dave/.python-eggs/cx_Oracle-5.0.3-py2.6-macosx-10.6-universal.egg-tmp/cx_Oracle.so (for architecture ppc7400): Mach-O bundle ppc /Users/dave/.python-eggs/cx_Oracle-5.0.3-py2.6-macosx-10.6-universal.egg-tmp/cx_Oracle.so (for architecture x86_64): Mach-O 64-bit bundle x86_64

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  • Agilist, Heal Thyself!

    - by Dylan Smith
    I’ve been meaning to blog about a great experience I had earlier in the year at Prairie Dev Con Calgary.  Myself and Steve Rogalsky did a session that we called “Agilist, Heal Thyself!”.  We used a format that was new to me, but that Steve had seen used at another conference.  What we did was start by asking the audience to give us a list of challenges they had had when adopting agile.  We wrote them all down, then had everybody vote on the most interesting ones.  Then we split into two groups, and each group was assigned one of the agile challenges.  We had 20 minutes to discuss the challenge, and suggest solutions or approaches to improve things.  At the end of the 20 minutes, each of the groups gave a brief summary of their discussion and learning's, then we mixed up the groups and repeated with another 2 challenges. The 2 groups I was part of had some really interesting discussions, and suggestions: Unfinished Stories at the end of Sprints The first agile challenge we tackled, was something that every single Scrum team I have worked with has struggled with.  What happens when you get to the end of a Sprint, and there are some stories that are only partially completed.  The team in question was getting very de-moralized as they felt that every Sprint was a failure as they never had a set of fully completed stories. How do you avoid this? and/or what do you do when it happens? There were 2 pieces of advice that were well received: 1. Try to bring stories to completion before starting new ones.  This is advice I give all my Scrum teams.  If you have a 3-week sprint, what happens all too often is you get to the end of week 2, and a lot of stories are almost done; but almost none are completely done.  This is a Bad Thing.  I encourage the teams I work with to only start a new story as a very last resort.  If you finish your task look at the stories in progress and see if there’s anything you can do to help before moving onto a new story.  In the daily standup, put a focus on seeing what stories got completed yesterday, if a few days go by with none getting completed, be sure this fact is visible to the team and do something about it.  Something I’ve been doing recently is introducing WIP (Work In Progress) limits while using Scrum.  My current team has 2-week sprints, and we usually have about a dozen or stories in a sprint.  We instituted a WIP limit of 4 stories.  If 4 stories have been started but not finished then nobody is allowed to start new stories.  This made it obvious very quickly that our QA tasks were our bottleneck (we have 4 devs, but only 1.5 testers).  The WIP limit forced the developers to start to pickup QA tasks before moving onto the next dev tasks, and we ended our sprints with many more stories completely finished than we did before introducing WIP limits. 2. Rather than using time-boxed sprints, why not just do away with them altogether and go to a continuous flow type approach like KanBan.  Limit WIP to keep things under control, but don’t have a fixed time box at the end of which all tasks are supposed to be done.  This eliminates the problem almost entirely.  At some points in the project (releases) you need to be able to burn down all the half finished stories to get a stable release build, but this probably occurs less often than every sprint, and there are alternative approaches to achieve it using branching strategies rather than forcing your team to try to get to Zero WIP every 2-weeks (e.g. when you are ready for a release, create a new branch for any new stories, but finish all existing stories in the current branch and release it). Trying to Introduce Agile into a team with previous Bad Agile Experiences One of the agile adoption challenges somebody described, was he was in a leadership role on a team he had recently joined – lets call him Dave.  This team was currently very waterfall in their ALM process, but they were about to start on a new green-field project.  Dave wanted to use this new project as an opportunity to do things the “right way”, using an Agile methodology like Scrum, adopting TDD, automated builds, proper branching strategies, etc.  The problem he was facing is everybody else on the team had previously gone through an “Agile Adoption” that was a horrible failure.  Dave blamed this failure on the consultant brought in previously to lead this agile transition, but regardless of the reason, the team had very negative feelings towards agile, and was very resistant to trying it out again.  Dave possibly had the authority to try to force the team to adopt Agile practices, but we all know that doesn’t work very well.  What was Dave to do? Ultimately, the best advice was to question *why* did Dave want to adopt all these various practices. Rather than trying to convince his team that these were the “right way” to run a dev project, and trying to do a Big Bang approach to introducing change.  He would be better served by identifying problems the team currently faces, have a discussion with the team to get everybody to agree that specific problems existed, then have an open discussion about ways to address those problems.  This way Dave could incrementally introduce agile practices, and he doesn’t even need to identify them as “agile” practices if he doesn’t want to.  For example, when we discussed with Dave, he said probably the teams biggest problem was long periods without feedback from users, then finding out too late that the software is not going to meet their needs.  Rather than Dave jumping right to introducing Scrum and all it entails, it would be easier to get buy-in from team if he framed it as a discussion of existing problems, and brainstorming possible solutions.  And possibly most importantly, don’t try to do massive changes all at once with a team that has not bought-into those changes.  Taking an incremental approach has a greater chance of success. I see something similar in my day job all the time too.  Clients who for one reason or another claim to not be fans of agile (or not ready for agile yet).  But then they go on to ask me to help them get shorter feedback cycles, quicker delivery cycles, iterative development processes, etc.  It’s kind of funny at times, sometimes you just need to phrase the suggestions in terms they are using and avoid the word “agile”. PS – I haven’t blogged all that much over the past couple of years, but in an attempt to motivate myself, a few of us have accepted a blogger challenge.  There’s 6 of us who have all put some money into a pool, and the agreement is that we each need to blog at least once every 2-weeks.  The first 2-week period that we miss we’re eliminated.  Last person standing gets the money.  So expect at least one blog post every couple of weeks for the near future (I hope!).  And check out the blogs of the other 5 people in this blogger challenge: Steve Rogalsky: http://winnipegagilist.blogspot.ca Aaron Kowall: http://www.geekswithblogs.net/caffeinatedgeek Tyler Doerkson: http://blog.tylerdoerksen.com David Alpert: http://www.spinthemoose.com Dave White: http://www.agileramblings.com (note: site not available yet.  should be shortly or he owes me some money!)

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  • Regex to identify rows that do not contain exact number of occurences of quotemark character using Notepad++

    - by SamAspin
    I would like to be able to jump to rows that dont contain 6 quotemarks in a quoted-CSV file as it feels like a good way to identify broken rows. I think using a regular expression with Notepad++'s find features would be a sensible approach but I'm not sure how to pick the rows up. 6 quotemarks (") would suggest a complete row so I want to skip to any row that does not contain 6. Here is some sample data to play with, in this example its the 4th line I'd like to jump to "sam","mark","dave" "sam","mark","dave" "sam","mark","dave" "sam","mark"," dave" "sam","mark","dave" "sam","mark","dave"

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  • Munin node not listing any plugins on new Fedora 14 installation

    - by Dave Forgac
    I have just installed munin-node from the base repo on Fedora 14 and then started it. I found that my munin server is not able to collect data from this node so I tried connecting via telnet to test. When connecting via telnet I see that no plugins are listed: [dave@host ~]# telnet localhost 4949 Trying 127.0.0.1... Connected to localhost. Escape character is '^]'. # munin node at host.example.com list quit Connection closed by foreign host. [dave@host ~]# I did not modify anything after the installation. The munin-node.conf is allowing connections from 127.0.0.1 and the default set of plugins in /etc/munin/plugins/ are symlinked to the plugins in /usr/share/munin/plugins/. Here is the working output of the telnet test of the 'list' command should look like (this is on a Fedora 13 host): [dave@www ~]$ telnet localhost 4949 Trying 127.0.0.1... Connected to localhost. Escape character is '^]'. # munin node at www.example.com list apache_accesses apache_processes apache_volume cpu df df_inode entropy forks fw_packets if_err_eth0 if_err_eth1 if_eth0 if_eth1 interrupts iostat iostat_ios irqstats load memory munin_stats mysql_ mysql_bytes mysql_innodb mysql_queries mysql_slowqueries mysql_threads netstat open_files open_inodes postfix_mailqueue postfix_mailvolume proc_pri processes swap threads uptime users vmstat yum quit Connection closed by foreign host. [dave@www ~]$ Edited to show output of munin-node-configure: [root@host ~]# munin-node-configure Plugin | Used | Extra information ------ | ---- | ----------------- acpi | no | amavis | no | ... http_loadtime | no | if_ | yes | eth1 eth0 if_err_ | yes | eth0 eth1 ifx_concurrent_sessions_ | no | interrupts | yes | ... uptime | yes | users | yes | varnish_ | no | vserver_resources | no | yum | yes | zimbra_ | no | Any suggestions on what to check next?

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  • SQLAuthority News – A Successful Community TechDays at Ahmedabad – December 11, 2010

    - by pinaldave
    We recently had one of the best community events in Ahmedabad. We were fortunate that we had SQL Experts from around the world to have presented at this event. This gathering was very special because besides Jacob Sebastian and myself, we had two other speakers traveling all the way from Florida (Rushabh Mehta) and Bangalore (Vinod Kumar).There were a total of nearly 170 attendees and the event was blast. Here are the details of the event. Pinal Dave Presenting at Community Tech Days On the day of the event, it seemed to be the coldest day in Ahmedabad but I was glad to see hundreds of people waiting for the doors to be opened some hours before. We started the day with hot coffee and cookies. Yes, food first; and it was right after my keynote. I could clearly see that the coffee did some magic right away; the hall was almost full after the coffee break. Jacob Sebastian Presenting at Community Tech Days Jacob Sebastian, an SQL Server MVP and a close friend of mine, had an unusual job of surprising everybody with an innovative topic accompanied with lots of question-and-answer portions. That’s definitely one thing to love Jacob, that is, the novelty of the subject. His presentation was entitled “Best Database Practices for the .Net”; it really created magic on the crowd. Pinal Dave Presenting at Community Tech Days Next to Jacob Sebastian, I presented “Best Database Practices for the SharePoint”. It was really fun to present Database with the perspective of the database itself. The main highlight of my presentation was when I talked about how one can speed up the database performance by 40% for SharePoint in just 40 seconds. It was fun because the most important thing was to convince people to use the recommendation as soon as they walk out of the session. It was really amusing and the response of the participants was remarkable. Pinal Dave Presenting at Community Tech Days My session was followed by the most-awaited session of the day: that of Rushabh Mehta. He is an international BI expert who traveled all the way from Florida to present “Self Service BI” session. This session was funny and truly interesting. In fact, no one knew BI could be this much entertaining and fascinating. Rushabh has an appealing style of presenting the session; he instantly got very much interaction from the audience. Rushabh Mehta Presenting at Community Tech Days We had a networking lunch break in-between, when we talked about many various topics. It is always interesting to get in touch with the Community and feel a part of it. I had a wonderful time during the break. Vinod Kumar Presenting at Community Tech Days After lunch was apparently the most difficult session for the presenter as during this time, many people started to fall sleep and get dizzy. This spot was requested by Microsoft SQL Server Evangelist Vinod Kumar himself. During our discussion he suggested that if he gets this slot he would make sure people are up and more interactive than during the morning session. Just like always, this session was one of the best sessions ever. Vinod is true to his word as he presented the subject of “Time Management for Developer”. This session was the biggest hit in the event because the subject was instilled in the mind of every participant. Vinod Kumar Presenting at Community Tech Days Vinod’s session was followed by his own small session. Due to “insistent public demand”, he presented an interesting subject, “Tricks and Tips of SQL Server“. In 20 minutes he has done another awesome job and all attendees wanted more of the tricks. Just as usual he promised to do that next time for us. Vinod’s session was succeeded by Prabhjot Singh Bakshi’s session. He presented an appealing Silverlight concept. Just the same, he did a great job and people cheered him. Prabhjot Presenting at Community Tech Days We had a special invited speaker, Dhananjay Kumar, traveling all the way from Pune. He always supports our cause to help the Community in empowering participants. He presented the topic about Win7 Mobile and SharePoint integration. This was something many did not even expect to be possible. Kudos to Dhananjay for doing a great job. Dhananjay Kumar Presenting at Community Tech Days All in all, this event was one of the best in the Community Tech Days series in Ahmedabad. We were fortunate that legends from the all over the world were present here to present to the Community. I’d say never underestimate the power of the Community and its influence over the direction of the technology. Vinod Kumar Presenting trophy to Pinal Dave Vinod Kumar Presenting trophy to Pinal Dave This event was a very special gathering to me personally because of your support to the vibrant Community. The following awards were won for last year’s performance: Ahmedabad SQL Server User Group (President: Jacob Sebastian; Leader: Pinal Dave) – Best Tier 2 User Group Best Development Community Individual Contributor – Pinal Dave Speakers I was very glad to receive the award for our entire Community. Attendees at Community Tech Days I want to say thanks to Rushabh Mehta, Vinod Kumar and Dhananjay Kumar for visiting the city and presenting various technology topics in Community Tech Days. Reference: Pinal Dave (http://blog.SQLAuthority.com) Filed under: MVP, SQL, SQL Authority, SQL Query, SQL Server, SQL Tips and Tricks, SQLAuthority Author Visit, SQLAuthority News, T SQL, Technology

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  • Listing common SQL Code Smells.

    - by Phil Factor
    Once you’ve done a number of SQL Code-reviews, you’ll know those signs in the code that all might not be well. These ’Code Smells’ are coding styles that don’t directly cause a bug, but are indicators that all is not well with the code. . Kent Beck and Massimo Arnoldi seem to have coined the phrase in the "OnceAndOnlyOnce" page of www.C2.com, where Kent also said that code "wants to be simple". Bad Smells in Code was an essay by Kent Beck and Martin Fowler, published as Chapter 3 of the book ‘Refactoring: Improving the Design of Existing Code’ (ISBN 978-0201485677) Although there are generic code-smells, SQL has its own particular coding habits that will alert the programmer to the need to re-factor what has been written. See Exploring Smelly Code   and Code Deodorants for Code Smells by Nick Harrison for a grounding in Code Smells in C# I’ve always been tempted by the idea of automating a preliminary code-review for SQL. It would be so useful to trawl through code and pick up the various problems, much like the classic ‘Lint’ did for C, and how the Code Metrics plug-in for .NET Reflector by Jonathan 'Peli' de Halleux is used for finding Code Smells in .NET code. The problem is that few of the standard procedural code smells are relevant to SQL, and we need an agreed list of code smells. Merrilll Aldrich made a grand start last year in his blog Top 10 T-SQL Code Smells.However, I'd like to make a start by discovering if there is a general opinion amongst Database developers what the most important SQL Smells are. One can be a bit defensive about code smells. I will cheerfully write very long stored procedures, even though they are frowned on. I’ll use dynamic SQL occasionally. You can only use them as an aid for your own judgment and it is fine to ‘sign them off’ as being appropriate in particular circumstances. Also, whole classes of ‘code smells’ may be irrelevant for a particular database. The use of proprietary SQL, for example, is only a ‘code smell’ if there is a chance that the database will have to be ported to another RDBMS. The use of dynamic SQL is a risk only with certain security models. As the saying goes,  a CodeSmell is a hint of possible bad practice to a pragmatist, but a sure sign of bad practice to a purist. Plamen Ratchev’s wonderful article Ten Common SQL Programming Mistakes lists some of these ‘code smells’ along with out-and-out mistakes, but there are more. The use of nested transactions, for example, isn’t entirely incorrect, even though the database engine ignores all but the outermost: but it does flag up the possibility that the programmer thinks that nested transactions are supported. If anything requires some sort of general agreement, the definition of code smells is one. I’m therefore going to make this Blog ‘dynamic, in that, if anyone twitters a suggestion with a #SQLCodeSmells tag (or sends me a twitter) I’ll update the list here. If you add a comment to the blog with a suggestion of what should be added or removed, I’ll do my best to oblige. In other words, I’ll try to keep this blog up to date. The name against each 'smell' is the name of the person who Twittered me, commented about or who has written about the 'smell'. it does not imply that they were the first ever to think of the smell! Use of deprecated syntax such as *= (Dave Howard) Denormalisation that requires the shredding of the contents of columns. (Merrill Aldrich) Contrived interfaces Use of deprecated datatypes such as TEXT/NTEXT (Dave Howard) Datatype mis-matches in predicates that rely on implicit conversion.(Plamen Ratchev) Using Correlated subqueries instead of a join   (Dave_Levy/ Plamen Ratchev) The use of Hints in queries, especially NOLOCK (Dave Howard /Mike Reigler) Few or No comments. Use of functions in a WHERE clause. (Anil Das) Overuse of scalar UDFs (Dave Howard, Plamen Ratchev) Excessive ‘overloading’ of routines. The use of Exec xp_cmdShell (Merrill Aldrich) Excessive use of brackets. (Dave Levy) Lack of the use of a semicolon to terminate statements Use of non-SARGable functions on indexed columns in predicates (Plamen Ratchev) Duplicated code, or strikingly similar code. Misuse of SELECT * (Plamen Ratchev) Overuse of Cursors (Everyone. Special mention to Dave Levy & Adrian Hills) Overuse of CLR routines when not necessary (Sam Stange) Same column name in different tables with different datatypes. (Ian Stirk) Use of ‘broken’ functions such as ‘ISNUMERIC’ without additional checks. Excessive use of the WHILE loop (Merrill Aldrich) INSERT ... EXEC (Merrill Aldrich) The use of stored procedures where a view is sufficient (Merrill Aldrich) Not using two-part object names (Merrill Aldrich) Using INSERT INTO without specifying the columns and their order (Merrill Aldrich) Full outer joins even when they are not needed. (Plamen Ratchev) Huge stored procedures (hundreds/thousands of lines). Stored procedures that can produce different columns, or order of columns in their results, depending on the inputs. Code that is never used. Complex and nested conditionals WHILE (not done) loops without an error exit. Variable name same as the Datatype Vague identifiers. Storing complex data  or list in a character map, bitmap or XML field User procedures with sp_ prefix (Aaron Bertrand)Views that reference views that reference views that reference views (Aaron Bertrand) Inappropriate use of sql_variant (Neil Hambly) Errors with identity scope using SCOPE_IDENTITY @@IDENTITY or IDENT_CURRENT (Neil Hambly, Aaron Bertrand) Schemas that involve multiple dated copies of the same table instead of partitions (Matt Whitfield-Atlantis UK) Scalar UDFs that do data lookups (poor man's join) (Matt Whitfield-Atlantis UK) Code that allows SQL Injection (Mladen Prajdic) Tables without clustered indexes (Matt Whitfield-Atlantis UK) Use of "SELECT DISTINCT" to mask a join problem (Nick Harrison) Multiple stored procedures with nearly identical implementation. (Nick Harrison) Excessive column aliasing may point to a problem or it could be a mapping implementation. (Nick Harrison) Joining "too many" tables in a query. (Nick Harrison) Stored procedure returning more than one record set. (Nick Harrison) A NOT LIKE condition (Nick Harrison) excessive "OR" conditions. (Nick Harrison) User procedures with sp_ prefix (Aaron Bertrand) Views that reference views that reference views that reference views (Aaron Bertrand) sp_OACreate or anything related to it (Bill Fellows) Prefixing names with tbl_, vw_, fn_, and usp_ ('tibbling') (Jeremiah Peschka) Aliases that go a,b,c,d,e... (Dave Levy/Diane McNurlan) Overweight Queries (e.g. 4 inner joins, 8 left joins, 4 derived tables, 10 subqueries, 8 clustered GUIDs, 2 UDFs, 6 case statements = 1 query) (Robert L Davis) Order by 3,2 (Dave Levy) MultiStatement Table functions which are then filtered 'Sel * from Udf() where Udf.Col = Something' (Dave Ballantyne) running a SQL 2008 system in SQL 2000 compatibility mode(John Stafford)

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  • Craftsmanship Tour: Day 2 Obtiva

    - by Liam McLennan
    I like Chicago. It is a great city for travellers. From the moment I got off the plane at O’Hare everything was easy. I took the train to ‘the Loop’ and walked around the corner to my hotel, Hotel Blake on Dearborn St. Sadly, the elevated train lines in downtown Chicago remind me of ‘Shall We Dance’. Hotel Blake is excellent (except for the breakfast) and the concierge directed me to a pizza place called Lou Malnati's for Chicago style deep-dish pizza. Lou Malnati’s would be a great place to go with a group of friends. I felt strange dining there by myself, but the food and service were excellent. As usual in the United States the portion was so large that I could not finish it, but oh how I tried. Dave Hoover, who invited me to Obtiva for the day, had asked me to arrive at 9:45am. I was up early and had some time to kill so I stopped at the Willis Tower, since it was on my way to the office. Willis Tower is 1,451 feet (442 m) tall and has an observation deck at the top. Around the observation deck are a set of acrylic boxes, protruding from the side of the building. Brave soles can walk out on the perspex and look between their feet all the way down to the street. It is unnerving. Obtiva is a progressive, craftsmanship-focused software development company in downtown Chicago. Dave even wrote a book, Apprenticeship Patterns, that provides a catalogue of patterns to assist aspiring software craftsmen to achieve their goals. I spent the morning working in Obtiva’s software studio, an open xp-style office that houses Obtiva’s in-house development team. For lunch Dave Hoover, Corey Haines, Cory Foy and I went to a local Greek restaurant (not Dancing Zorbas). Dave, Corey and Cory are three smart and motivated guys and I found their ideas enlightening. It was especially great to chat with Corey Haines since he was the inspiration for my craftsmanship tour in the first place. After lunch I recorded a brief interview with Dave. Unfortunately, the battery in my camera went flat so I missed recording some interesting stuff. Interview with Dave Hoover In the evening Obtiva hosted an rspec hackfest with David Chelimsky and others. This was an excellent opportunity to be around some of the very best ruby programmers. At 10pm I went back to my hotel to get some rest before my train north the next morning.

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  • How do I get rid of the drive mount confirmation question for sshFS on boot?

    - by Dave M G
    With help from this site, I was able to set up an SSHFS connection between two computers on my LAN so that one auto mounts on the other at boot time. Everything works, but there is this annoying confirmation that comes up whenever I boot: An error occurred while mounting /home/dave/Mythbuntu. Press S to skip mounting or M or Manual recovery If I press S, then booting continues, and my drive is mounted as hoped, so it seems like even though I "skipped" it, maybe it tried again and succeeded later in the boot process. I followed the instructions here to set up "if up / if down" scripts, and here is my current /etc/fstab: sshfs#[email protected]:/home/mythbuntu /home/dave/Mythbuntu fuse auto,users,exec,uid=1000,gid=1000,allow_other,reconnect,transform_symlinks,BatchMode=yes 0 0 Although the mounting is working, this step of having to press S every time I boot is obviously kind of a hassle. How do I configure my computer so I don't have to do that, and so that my other computer will still automount?

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  • How do I get rid of this drive mount confirmation question when booting the computer?

    - by Dave M G
    With help from this site, I was able to set up an SSHFS connection between two computers on my LAN so that one auto mounts on the other at boot time. Everything works, but there is this annoying confirmation that comes up whenever I boot: An error occurred while mounting /home/dave/Mythbuntu. Press S to skip mounting or M or Manual recovery If I press S, then booting continues, and my drive is mounted as hoped, so it seems like even though I "skipped" it, maybe it tried again and succeeded later in the boot process. I followed the instructions here to set up "if up / if down" scripts, and here is my current /etc/fstab: sshfs#[email protected]:/home/mythbuntu /home/dave/Mythbuntu fuse auto,users,exec,uid=1000,gid=1000,allow_other,reconnect,transform_symlinks,BatchMode=yes 0 0 Although the mounting is working, this step of having to press S every time I boot is obviously kind of a hassle. How do I configure my computer so I don't have to do that, and so that my other computer will still automount?

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  • Python soap using soaplib (server) and suds (client)

    - by Celso Axelrud
    This question is related to: http://stackoverflow.com/questions/1751027/python-soap-server-client In the case of soap with python, there are recommendation to use soaplib (http://wiki.github.com/jkp/soaplib) as soap server and suds (https://fedorahosted.org/suds/) as soap client. My target is to create soap services in python that can be consumed by several clients (java, etc). I tried the HelloWorld example from soaplib (http://trac.optio.webfactional.com/wiki/HelloWorld). It works well when the client is also using soaplib. Then, I tried to use suds as client consuming the HelloWorld services and it fail. -Why this is happening? Does soaplib server has problems to consumed by different clients? Here the code for the server: from soaplib.wsgi_soap import SimpleWSGISoapApp from soaplib.service import soapmethod from soaplib.serializers.primitive import String, Integer, Arraycode class HelloWorldService(SimpleWSGISoapApp): @soapmethod(String,Integer,_returns=Array(String)) def say_hello(self,name,times): results = [] for i in range(0,times): results.append('Hello, %s'%name) return results if __name__=='__main__': from cherrypy.wsgiserver import CherryPyWSGIServer #from cherrypy._cpwsgiserver import CherryPyWSGIServer # this example uses CherryPy2.2, use cherrypy.wsgiserver.CherryPyWSGIServer for CherryPy 3.0 server = CherryPyWSGIServer(('localhost',7789),HelloWorldService()) server.start() This is the soaplib client: from soaplib.client import make_service_client from SoapServerTest_1 import HelloWorldService client = make_service_client('http://localhost:7789/',HelloWorldService()) print client.say_hello("Dave",5) Results: >>> ['Hello, Dave', 'Hello, Dave', 'Hello, Dave', 'Hello, Dave', 'Hello, Dave'] This is the suds client: from suds.client import Client url = 'http://localhost:7789/HelloWordService?wsdl' client1 = Client(url) client1.service.say_hello("Dave",5) Results: >>> Unhandled exception while debugging... Traceback (most recent call last): File "C:\Python25\Lib\site-packages\RTEP\Sequencing\SoapClientTest_1.py", line 10, in <module> client1.service.say_hello("Dave",5) File "c:\python25\lib\site-packages\suds\client.py", line 537, in __call__ return client.invoke(args, kwargs) File "c:\python25\lib\site-packages\suds\client.py", line 597, in invoke result = self.send(msg) File "c:\python25\lib\site-packages\suds\client.py", line 626, in send result = self.succeeded(binding, reply.message) File "c:\python25\lib\site-packages\suds\client.py", line 658, in succeeded r, p = binding.get_reply(self.method, reply) File "c:\python25\lib\site-packages\suds\bindings\binding.py", line 158, in get_reply result = unmarshaller.process(nodes[0], resolved) File "c:\python25\lib\site-packages\suds\umx\typed.py", line 66, in process return Core.process(self, content) File "c:\python25\lib\site-packages\suds\umx\core.py", line 48, in process return self.append(content) File "c:\python25\lib\site-packages\suds\umx\core.py", line 63, in append self.append_children(content) File "c:\python25\lib\site-packages\suds\umx\core.py", line 140, in append_children cval = self.append(cont) File "c:\python25\lib\site-packages\suds\umx\core.py", line 61, in append self.start(content) File "c:\python25\lib\site-packages\suds\umx\typed.py", line 77, in start found = self.resolver.find(content.node) File "c:\python25\lib\site-packages\suds\resolver.py", line 341, in find frame = Frame(result, resolved=known, ancestry=ancestry) File "c:\python25\lib\site-packages\suds\resolver.py", line 473, in __init__ resolved = type.resolve() File "c:\python25\lib\site-packages\suds\xsd\sxbasic.py", line 63, in resolve raise TypeNotFound(qref) TypeNotFound: Type not found: '(string, HelloWorldService.HelloWorldService, )'

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