On Mon, Feb 15, 2010 at 7:11 PM, Bruce Momjian <br...@momjian.us> wrote: > 1. Why do we only do bind-level planning for anonymous wire-level queries? > > 2. I realize we did anonymous-only because that was the only way we had > in the protocol to _signal_ bind-time planning, but didn't we think of > this when we were implementing the wire-level protocol?
Is there any other difference between anonymous and non-anonymous queries? If this is the only major difference do we need to separate them? Is there any particular reason a driver would need two prepared queries if they're both just going to be planned at execution time? Incidentally, can you have two active anonymous portals at the same time? > 4. Why don't we just always do planning at first bind time? When is > that worse than using generic values? > > 6. When do our generic columns costs significantly worse than having > specific constants? I assume unique columns are fine with generic > constants. Well using parameters will always have a better chance of producing a better plan but that's not the only factor people consider important. For a lot of users *predictability* is more important than absolute performance. If my web server could run 10% faster that might be nice but if it's capable of keeping up at its current speed it's not terribly important. But if it means it crashes once a day because some particular combination of parameters causes a bad plan to be used for a specific user that's a bad trade-off. -- greg -- Sent via pgsql-hackers mailing list (pgsql-hackers@postgresql.org) To make changes to your subscription: http://www.postgresql.org/mailpref/pgsql-hackers
