Markus Schaber wrote:
> Hi, Oliver,
>
> Oliver Jowett wrote:
>>Isn't this just a very roundabout way of overriding the planner? i.e.
>>what you are really doing is saying "ignore your statistics, I know more
>>about the parameter values I'm going to give you than I'm actually
>>telling you"..
>
>
> No, it's telling the planner "You can assume that all those queries for
> my statement are similar enough that the same query plan will fit them,
> so you can safe the overhead of both parsing and planning".
What I mean is, if you are prepared to say that, what you are really
wanting is to second-guess the planner and tell the server "use *THIS*
plan" explicitly .. In both approaches, you (the app developer) need
detailed knowledge about what sort of plans work for the parameters &
query you are using (for your particular server version and dataset etc).
Doing that at the Parse/Bind level doesn't seem right and in fact seems
even more errorprone than explicitly specifying a plan, since you are
relying on the planner picking a particular plan for a particular set of
parameter values that you happened to use first which may or may not
always be true depending on things like the current state of DB statistics..
-O
