Graybeard52
2425 pts. | Oct 14 2009 5:16PM GMT
Performance can be a tricky thing, because it all depends on so many factors.
My experience with Performance Adjuster was worse than yours. I am running several MQT builds during the night time hours over some large files with 60-70 join files. Suddenly, run time want from 2 hours to 24+ hours (did not let it finish). Here is what the problem was: SQL optimizes based on available memory, but does NOT lock that memory. Consequently my system was optimizing based on about 6G of memory. But other jobs running in QBATCH eventually consumed most of the memory, and SQL went to a near stop trying to run in justa little memory. Perf Adjust just kept pulling it away from SQL.
My solution was to run SQL thru a seperate memory pool, with 2G minimum and 2G maximum. Now Perf Adjust does nothing with it, SQL optimizes at 2G and gets to keep it for the entire run. Those queries are now down to about 20 minutes each, and smaller queries have benefited as well.






