Solving Blocking Without Sysadmin

Michael Swart has a story on blocking due to an edge case scenario:

SQL Server was struggling to compile the procedure in time and the application wouldn’t let it catch its breath. The query optimizer was attempting to create statistics automatically that it needed for optimizing the query, but after thirty seconds, the application got impatient and cancelled the query.

So the compilation of the procedure was cancelled and this caused two things to happen. First, the creation of the statistics was cancelled. Second, the next session in line was allowed to run. But the problem was that the next session had already spent 28 seconds blocked by the first session and only had two seconds to try to compile a query before getting cancelled itself.

The frequent calls to the procedure meant that nobody had time to compile this query. And we were stuck in an endless cycle of sessions that wanted to compile a procedure, but could never get enough time to do it.

There are two important lessons here:  how Michael solved the problem and also a reminder that plan cache entries are dependent upon specific application settings.

Related Posts

Change Tracking in SQL Server

Tim Weigel covers the basics of change tracking in SQL Server: There aren’t a lot of parameters here. You can set change tracking on or off, you can specify your retention period, and you can specify whether to enable auto-cleanup or not. For the retention period, you have the choice of DAYS, HOURS, or MINUTES. […]

Read More

Maintaining SSISDB

John McCormack was in a jam: I made 2 unsuccessful attempts at running the SSIS Server Maintenance Job. However, after several hours of processing and still no available free space in the database, I knew the job wasn’t coping with the sheer number of rows it had to delete. The deletes all happen from the parent table […]

Read More

Categories

December 2016
MTWTFSS
« Nov Jan »
 1234
567891011
12131415161718
19202122232425
262728293031