Great. Based on this, do you have a patch that is ready to apply. ---------------------------------------------------------------------------
Heikki Linnakangas wrote: > Heikki Linnakangas wrote: > > In any case, I'd like to see more test results before we make a > > decision. I'm running tests with DBT-2 and a seq scan running in the > > background to see if the cache-spoiling effect shows up. I'm also trying > > to get hold of some bigger hardware to run on. Running these tests takes > > some calendar time, but the hard work has already been done. I'm going > > to start reviewing Jeff's synchronized scans patch now. > > Here are the results of the DBT-2 tests: > > http://community.enterprisedb.com/seqscan/imola/ > > In each of these tests, at the end of rampup a script is started that > issues a "SELECT COUNT(*) FROM stock" in a loop, with 2 minute delay > between end of previous query and start of next one. > > The patch makes the seq scans go significantly faster. In the 1 hour > test period, the patched tests perform roughly 30-100% as many selects > as unpatched tests. > > With 100 and 105 warehouses, it also significantly reduces the impact of > the seq scan on other queries; response times are lower with the patch. > With 120 warehouses the reduction of impact is not as clear, but when > you plot the response times it's still there (the plots on the "response > times charts"-page are useless because they're overwhelmed by the > checkpoint spike). > > -- > Heikki Linnakangas > EnterpriseDB http://www.enterprisedb.com > > ---------------------------(end of broadcast)--------------------------- > TIP 5: don't forget to increase your free space map settings -- Bruce Momjian <[EMAIL PROTECTED]> http://momjian.us EnterpriseDB http://www.enterprisedb.com + If your life is a hard drive, Christ can be your backup. + ---------------------------(end of broadcast)--------------------------- TIP 9: In versions below 8.0, the planner will ignore your desire to choose an index scan if your joining column's datatypes do not match
