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K. Brian Kelley - Databases, Infrastructure, and Security

IT Security, MySQL, Perl, SQL Server, and Windows technologies.

Best Thing I Learned at PASS Summit

If you haven't heard, PASS is running a contest where you could win conference registration to this year's PASS Community Summit or, if you have that covered, 4 nights coverage of hotel costs. All you have to do is enter by July 1. Check the link for details. Here's my best thing I learned, which was from the 2004 PASS Community Summit:

It was a packed, standing-room only presentation. The late Ken Henderson was talking on how SQL Server allocated memory, and was talking about the MemToLeave region. He discussed how large execution plans can tap memory from this space and how any such allocations require contiguous memory. So if MemToLeave is fragmented and you need a large amount of memory, a contiguous block may not be available, generating an error. I slotted away this knowledge, never thinking I would use it.

Fast forward a couple of years when one of our teams kept reporting that one of their nightly processes was failing with an error indicating that it couldn’t allocate contiguous memory. My mind went back to the Henderson talk. The error indicated it couldn’t allocate 229 MB of contiguous memory. When the default setup had only 256 MB total, it wasn’t surprising. Some were blaming SQL Server and asking a case be opened with Microsoft. I pointed to the amount of memory and asked what needed that much. We looked and found a horrendous query in a looping piece of code. It was being built dynamically, adding an AND clause to the WHERE each time it processed a record. This was to exclude said record and the process had tens of thousands of rows to process nightly. I can’t imagine what that execution plan looked like. We had a likely culprit and forced them to rewrite the process. After they did, the process didn’t fail again.

 

Comments

Posted by Steve Jones on 19 June 2009

So, did that knowledge make the conference worthwhile? Savings in time? An MS case is $250, or it used to be, so I'm wondering how this compares in your mind.

Posted by K. Brian Kelley on 19 June 2009

That plus other things, too. I picked out this one item and kept it under 250 words, as per contest rules, but yeah, the conference was definitely worth the time and money, had I been paying my own way. This was the most significant nugget I picked up with respect to impact for a single event, but I learned a ton and I met a lot of great folks. Also, it got me away for a week to really focus on SQL Server. Being in the trenches every day, it was great to just be able to immerse in the technology and talk shop with folks in the same field. Same feeling I had when I went to TechEd a couple of years ago.

Posted by Steve Jones on 20 June 2009

Makes sense to me, and I would tend to agree it's worth the $$ to get away, learn, network, get inspired. Good hard evidence helps with managers, though. Having stories like this, maybe a nice compilation, might help others get funding.

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