Re: Avoiding bad prepared-statement plans.

On 02/26/2010 07:03 PM, Tom Lane wrote:
> Robert Haas<robertmhaas@gmail.com>  writes:
>    
>> Basically, what I really want here is some kind of keyword or other
>> syntax that I can stick into a PL/pgsql query that requests a replan
>> on every execution.
>>      
> Wouldn't it be better if it just did the right thing automatically?
>    

Yes please. :-) Often, we are just users of the application, and we do 
not have the freedom to change it.

> The sort of heuristic I'm envisioning would essentially do "replan every
> time" for some number of executions, and give up only if it noticed that
> it wasn't getting anything better than the generic plan.  So you'd have
> a fixed maximum overhead per session when the custom plan was useless,
> and the Right Thing when it wasn't.

My other comments aside - I think generic plan + specific plan where 
specific plan continues to beat generic plan, will meet the cases that 
really annoyed me, and would make a lot of us very happy... Thanks.

Cheers,
mark