so 17. 4. 2021 v 20:36 odesÃlatel Justin Pryzby <pry...@telsasoft.com> napsal:
> On Sat, Apr 17, 2021 at 05:22:59PM +0200, Pavel Stehule wrote: > > so 17. 4. 2021 v 17:09 odesÃlatel Justin Pryzby <pry...@telsasoft.com> > napsal: > > > > > On Sat, Apr 17, 2021 at 04:36:52PM +0200, Pavel Stehule wrote: > > > > today I worked on postgres's server used for critical service. > Because the > > > > application is very specific, we had to do final tuning on production > > > > server. I fix lot of queries, but I am not able to detect fast > queries that > > > > does full scan of middle size tables - to 1M rows. Surely I wouldn't > log > > > > all queries. Now, there are these queries with freq 10 per sec. > > > > > > > > Can be nice to have a possibility to set a log of queries that do > full > > > > scan and read more tuples than is specified limit or that does full > scan of > > > > specified tables. > > > > > > > > What do you think about the proposed feature? > > > > > > Are you able to use auto_explain with auto_explain.log_min_duration ? > > > > Unfortunately, I cannot use it. This server executes 5K queries per > > seconds, and I am afraid to decrease log_min_duration. > > > > The logs are forwarded to the network and last time, when users played > with > > it, then they had problems with the network. > .. > > The fullscan of this table needs about 30ms and has 200K rows. So > > decreasing log_min_duration to this value is very risky. > > auto_explain.sample_rate should allow setting a sufficiently low value of > log_min_duration. It exists since v9.6. > > It cannot help - these queries are executed a few times per sec. In same time this server execute 500 - 1000 other queries per sec Regards Pavel > -- > Justin >
