Simon Riggs <si...@2ndquadrant.com> writes: > One of the things I was looking at doing was allowing the operator > estimation functions mark the plan as "one-shot" if they used > non-uniform data to predict the estimate. That would require most > functions to observe the rule that if a plan is marked unsafe then > nobody marks it safe again later. More of a guideline, really.
> For example, if we a doing a PK retrieval it will have a uniform > distribution and so we can always use the final plan, whereas a plan > that relates to a highly skewed distribution would be dangerous and so > would be marked one-shot. I fail to detect the sanity in that. You seem to be confusing "skewed" with "changing rapidly". There's no reason to assume that a nonuniform distribution is less stable than one that is uniform, and in any case we already invalidate all plans related to a table after any update of the statistics by ANALYZE. regards, tom lane -- Sent via pgsql-hackers mailing list (pgsql-hackers@postgresql.org) To make changes to your subscription: http://www.postgresql.org/mailpref/pgsql-hackers