Re: A performance issue with Memoize

David Rowley <dgrowleyml(at)gmail(dot)com> writes:
> I'd feel better about doing it your way if Tom could comment on if
> there was a reason he put the function calls that way around in
> 5ebaaa494.

Apologies for not having noticed this thread before. I'm taking
a look at it now. However, while sniffing around this I found
what seems like an oversight in paramassign.c's
assign_param_for_var(): it says it should compare all the same
fields as _equalVar except for varlevelsup, but it's failing to
compare varnullingrels. Is that a bug? It's conceivable that
it's not possible to get here with varnullingrels different and
all else the same, but I don't feel good about that proposition.

I tried adding

@@ -91,7 +91,10 @@ assign_param_for_var(PlannerInfo *root, Var *var)
pvar->vartype == var->vartype &&
pvar->vartypmod == var->vartypmod &&
pvar->varcollid == var->varcollid)
+ {
+ Assert(bms_equal(pvar->varnullingrels, var->varnullingrels));
return pitem->paramId;
+ }
}
}

This triggers no failures in the regression tests, but we know
how little that proves.

Anyway, that's just a side observation unrelated to the problem
at hand. More later.

regards, tom lane