Re: Transient plans versus the SPI API

Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us> writes:
> I think we'll be a lot better off with the framework discussed last
> year: build a generic plan, as well as custom plans for the first few
> sets of parameter values, and then observe whether there's a significant
> reduction in estimated costs for the custom plans.

Another way here would be to cache more than a single plan and to keep
execution time samples or some other relevant runtime characteristics.
Then what we need would be a way to switch from a plan to another at run
time on some conditions, like realizing that the reason why the planner
thought a nestloop would be perfect is obviously wrong, or maybe just
based on runtime characteristics.

> But in any case, it's way premature to be debating this until we have
> the infrastructure in which we can experiment with different policies.

That too.

Regards,
--
Dimitri Fontaine
http://2ndQuadrant.fr PostgreSQL : Expertise, Formation et Support