>This patch needs documentation. At a minimum, the new calls_underest >field needs to be listed in the description of the pg_stat_statements. I have attached a version which includes documentation. pg_stat_statements-identification-v4.patch.gz <http://postgresql.1045698.n5.nabble.com/file/n5770844/pg_stat_statements-identification-v4.patch.gz> >Pardon for not following the discussion: What exactly does the >calls_underest field mean? I couldn't decipher it from the patch. What >can an admin do with the value? How does it compare with just bumping up >pg_stat_statements.max? Paraphrasing the documentation. There is a possibility that,for queries which are tracked intermittently, could have their statistics silently reset. The calls_underest field gives an indication that a query has been tracked intermittently and consequently have a higher probability of erroneous statistics. Queries tracked constantly will have a zero value for calls_underest indicating zero probability of erroneous statistics. A greater value of calls_underest indicates greater degree of inconsistent tracking which in turn means greater possibility of erroneous statistics due to statistics being reset when query was not being tracked.
Increasing pg_stat_statements.max reduces the possibility of a query being tracked intermittently but does not address the problem of indicating the probability of erroneous statistics if the query is indeed being tracked intermittently. I do not believe the admin can influence the value of calls_underest as it is not a GUC parameter. We have a need to see this patch committed hence the revived interest in this thread regards Sameer -- View this message in context: http://postgresql.1045698.n5.nabble.com/pg-stat-statements-calls-under-estimation-propagation-tp5738128p5770844.html Sent from the PostgreSQL - hackers mailing list archive at Nabble.com. -- Sent via pgsql-hackers mailing list (pgsql-hackers@postgresql.org) To make changes to your subscription: http://www.postgresql.org/mailpref/pgsql-hackers
