On Sat, Aug 17, 2019 at 6:58 PM Daniel Migowski <dmigow...@ikoffice.de> wrote:
> Hello, > > attached you find a patch that adds a new GUC: > Quick questions before looking at the patch. > > prepared_statement_limit: > > - Do we have a consensus about the name of GUC? I don't think it is the right name for that. - Is this a WIP patch or the final patch? Because I can see TODO and non-standard comments in the patch. > Specifies the maximum amount of memory used in each session to > cache > parsed-and-rewritten queries and execution plans. This affects > the maximum memory > a backend threads will reserve when many prepared statements > are used. > The default value of 0 disables this setting, but it is > recommended to set this > value to a bit lower than the maximum memory a backend worker > thread should reserve > permanently. > > If the GUC is configured after each save of a CachedPlanSource, or after > creating a CachedPlan from it, the function > EnforcePreparedStatementLimit is called now. It checks the mem usage of > the existing saved CachedPlanSources and invalidates the query_list and > the gplan if available until the memory limit is met again. > > CachedPlanSource are removed-and-tailadded in the saved_plan_list > everytime GetCachedPlan is called on them so it can be used as a LRU list. > > I also reworked ResetPlanCache, PlanCacheRelCallback and > PlanCacheObjectCallback a bit so when a CachedPlanSource is invalidated > the query_list is not only marked as invalid but it is also fully > released to free memory here. > > Regards, > Daniel Migowski > > PS@Konstantin: This patch also includes the CachedPlanMemoryUsage > function you like, maybe you like the review the patch for me? > > -- Ibrar Ahmed
