Tom,
Even though we all agree default_statistics_target = 10 is too low, proposing a 40X increase in the default value requires more evidence than this. In particular, the prospect of a 1600-fold increase in the typical cost of eqjoinsel() is a mite scary.
It's a *completely* acceptable tradeoff for a *data warehousing* database, where queries take multiple seconds to execute even under the best plans ... and minutes or hours for the worst. And that's what I'm proposing a value of 400 for, if you read my posting rather than just Greg's outraged response.
(and yes, I've done this for multiple *production* data warehouses and the results have been good)
For a web database, keep it at 10. It might turn out that an increase to 25 or 50 would benefit even web applications, but we don't yet have the testing resources to determine that.
Of *course* it would be better for the DBA to go through and set statistics column-by-column. But few will.
--Josh -- Sent via pgsql-hackers mailing list (pgsql-hackers@postgresql.org) To make changes to your subscription: http://www.postgresql.org/mailpref/pgsql-hackers
