On 3/14/19 00:29, Stephan Schmidt wrote: > i’m currently working on a high Performance Database and want to make > sure that whenever there are slow queries during regular operations i’ve > got all Information about the query in my logs. So auto_explain come to > mind, but the documentation explicitly states that it Comes at a cost. > My Question is, how big is the latency added by auto_explain in > percentage or ms ? One thought - what if the problem query is a 4ms query that just went to 6ms but it's executed millions of times per second? That would create a 150% increase to the load on the system. The approach I've had the most success with is to combine active session sampling (from pg_stat_activity) with pg_stat_statements (ideally with periodic snapshots) to identify problematic SQL statements, then use explain analyze after you've identified them. There are a handful of extensions on the internet that can do active session sampling for you, and I've seen a few scripts that can be put into a scheduler to capture snapshots of stats tables. Maybe something to consider in addition to the auto_explain stuff. -Jeremy -- http://about.me/jeremy_schneider
