On Tue, Sep 22, 2015 at 4:40 PM, Tom Lane <t...@sss.pgh.pa.us> wrote: > I wonder whether the real problem here is failure to truncate statement > texts to something sane. Do we really need to record the whole text of > multi-megabyte statements? Especially if doing so could render the entire > feature nonfunctional?
I recently encountered a 9.4 customer database that had an insanely large query text stored by pg_stat_statements, apparently created as part of a process of kicking the tires of their new installation. I don't know how large it actually was, but it caused psql to stall for over 10 seconds. Insane queries happen, so truncating query text could conceal the extent of how unreasonable a query is. I think that the real problem here is that garbage collection needs to deal with OOM more appropriately. That's the only way there could be a problem with an in-flight query as opposed to a query that looks at pg_stat_statements, which seems to be Nasby's complaint. My guess is that this very large query involved a very large number of constants, possibly contained inside an " IN ( )". Slight variants of the same query, that a human would probably consider to be equivalent have caused artificial pressure on garbage collection. -- Peter Geoghegan -- Sent via pgsql-hackers mailing list (pgsql-hackers@postgresql.org) To make changes to your subscription: http://www.postgresql.org/mailpref/pgsql-hackers