Re: Prepared statements considered harmful

On Thu, August 31, 2006 18:56, Peter Eisentraut wrote:

> With time, it becomes ever clearer to me that prepared SQL statements are
> just
> a really bad idea. On some days, it seems like half the performance
> problems
> in PostgreSQL-using systems are because a bad plan was cached somewhere.

Is there any kind of pattern at all to this problem? Anything
recognizable? A few typical pitfalls?

Without knowing much of the internals, I could imagine [waves hands in
vague gestures] other options--something like recognizing major changes
that upset the cost functions that went into generating a plan, and
invalidating the plan based on those; or noting bad estimates somehow as
they become apparent during execution, and annotating the plan with a
"this assumption was a bad idea" marker so you'll do better next time.

I guess you can't go far wrong if you re-define "prepared" to mean merely
"pre-parsed," but it sounds like such a waste of opportunity...

Jeroen