> The hairiness is in the plan dependence (or independence) on parameter > values, ideally we only want to cache plans that would be good for all > parameter values, only the user knows that precisely. Although it could be > possible to examine the column histograms...
If cached plans would be implemented, the dependence on parameter values could be solved too: use special "fork" nodes in the plan which execute different sub-plans depending on special parameter values/ranges, possibly looking up the stats at runtime, so that the plan is in a compiled state with the "decision points" wired in. This of course would mean a lot heavier planning and possibly a lot bigger plans, but you could afford that if you cache the plan. You could even have a special command to plan a query this way. Cheers, Csaba. -- Sent via pgsql-hackers mailing list (pgsql-hackers@postgresql.org) To make changes to your subscription: http://www.postgresql.org/mailpref/pgsql-hackers
