Re: Avoid unnecessary table open/close for TRUNCATE foo, foo, foo; kind of commands

[Fujii Masao]

On 2021/04/10 0:39, Amul Sul wrote:

On Fri, Apr 9, 2021 at 8:51 PM Bharath Rupireddy
<bharath.rupireddyforpostg...@gmail.com> wrote:

Hi,

While checking the ExecuteTruncate code for the FOREIGN TRUNCATE
feature, I saw that we filter out the duplicate relations specified in
the TRUNCATE command. But before skipping the duplicates, we are just
opening the relation, then if it is present in the already seen
relids, then closing it and continuing further.

I think we can just have the duplicate checking before table_open so
that in cases like TRUNCATE foo, foo, foo, foo; we could save costs of
table_open and table_close. Attaching a small patch. Thoughts?

This is just like what we already do for child tables, see following
in ExecuteTruncate:
             foreach(child, children)
             {
                 Oid            childrelid = lfirst_oid(child);

                 if (list_member_oid(relids, childrelid))
                     continue;

Well yes, the patch looks pretty much reasonable to be.

LGTM, too. I will commit this patch.
Though that code exists even in older version, I'm not thinking
to back-patch that because it's not a bug.

Regards,

--
Fujii Masao
Advanced Computing Technology Center
Research and Development Headquarters
NTT DATA CORPORATION