Re: making update/delete of inheritance trees scale better

Amit Langote <amitlangote09(at)gmail(dot)com> writes:
> On Tue, Mar 30, 2021 at 1:51 PM Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us> wrote:
>> Here's a v13 patchset that I feel pretty good about.

> Thanks. After staring at this for a day now, I do too.

Thanks for looking! Pushed after some more docs-fiddling and a final
read-through. I think the only code change from v13 is that I decided
to convert ExecGetJunkAttribute into a "static inline", since it's
just a thin wrapper around slot_getattr(). Doesn't really help
performance much, but it shouldn't hurt.

> ... The drop as partition count increases can
> be attributed to the fact that with a generic plan, there are a bunch
> of steps that must be done across all partitions, such as
> AcauireExecutorLocks(), ExecCheckRTPerms(), per-result-rel
> initializations in ExecInitModifyTable(), etc., even with the patched.
> As mentioned upthread, [1] can help with the last bit.

I'll try to find some time to look at that one.

I'd previously been thinking that we couldn't be lazy about applying
most of those steps at executor startup, but on second thought,
ExecCheckRTPerms should be a no-op anyway for child tables. So
maybe it would be okay to not take a lock, much less do the other
stuff, until the particular child table is stored into.

regards, tom lane