On 12 February 2012 22:28, Peter van Hardenberg <pvh@xxxxxx> wrote: > Yes, I think if we could normalize, anonymize, and randomly EXPLAIN > ANALYZE 0.1% of all queries that run on our platform we could look for > bad choices by the planner. I think the potential here could be quite > remarkable. Tom Lane suggested that plans, rather than the query tree, might be a more appropriate thing for the new pg_stat_statements to be hashing, as plans should be directly blamed for execution costs. While I don't think that that's appropriate for normalisation (consider that there'd often be duplicate pg_stat_statements entries per query), it does seem like an idea that could be worked into a future revision, to detect problematic plans. Maybe it could be usefully combined with auto_explain or something like that (in a revision of auto_explain that doesn't necessarily explain every plan, and therefore doesn't pay the considerable overhead of that instrumentation across the board). -- Peter Geoghegan http://www.2ndQuadrant.com/ PostgreSQL Development, 24x7 Support, Training and Services -- Sent via pgsql-performance mailing list (pgsql-performance@xxxxxxxxxxxxxx) To make changes to your subscription: http://www.postgresql.org/mailpref/pgsql-performance
