Le vendredi 18 décembre 2009 09:44:40, Takahiro Itagaki a écrit : > We have infrastructure to count numbers buffer access in 8.5 Alpha 3. > I'd like to add per-query buffer usage into contrib/pg_stat_statements. > > The pg_stat_statements view will have the same contents with > struct BufferUsage. Fields named shared_blks_{hit|read|written}, > local_blks_{hit|read|written}, and temp_blks_{read|written} > will be added to the view. > > We can determine slow queries not only based on durations but also > based on I/O or memory access count. Also, queries with non-zero > temp_blks_read means DBA need to consider increasing work_mem. Those > information would be useful to find where the server's bottleneck is. > > Additional management costs cannot be avoided, but I think it should be > not so high because we accumulate buffer usage only once per query, > while EXPLAIN BUFFERS is slow because we need per-tuple calculation. > > I'll submit this pg_stat_statements enhancement to the next commit fest. > Comments welcome.
Very good idea. Perhaps it can be usefull to have the percentage for hit/read ratio computed in the view ? > > Regards, > --- > Takahiro Itagaki > NTT Open Source Software Center > -- Cédric Villemain Administrateur de Base de Données Cel: +33 (0)6 74 15 56 53 http://dalibo.com - http://dalibo.org
signature.asc
Description: This is a digitally signed message part.