Re: ProcessUtility_hook

Robert Haas <robertmhaas(at)gmail(dot)com> wrote:

> Why does this patch #ifdef out the _PG_fini code in pg_stat_statements?

That's because _PG_fini is never called in current releases.
We could remove it completely, but I'd like to leave it for future
releases where _PG_fini callback is re-enabled.
Or, removing #ifdef (enabling _PG_fini function) is also harmless.

> Where you check for INSERT, UPDATE, and DELETE return codes in
> pgss_ProcessUtility, I think this deserves a comment explaining that
> these could occur as a result of EXECUTE. It wasn't obvious to me,
> anyway.

Like this?
/*
* Parse command tag to retrieve the number of affected rows.
* COPY command returns COPY tag. EXECUTE command might return INSERT,
* UPDATE, or DELETE tags, but we cannot retrieve the number of rows
* for SELECT. We assume other commands always return 0 row.
*/

> It seems to me that the current hook placement does not address this complaint
> >> I don't see why the hook function should have the ability to
> >> editorialize on the behavior of everything about ProcessUtility
> >> *except* the read-only-xact check.

I moved the initialization code of completionTag as the comment,
but check_xact_readonly() should be called before the hook.
Am I missing something?

Regards,
---
Takahiro Itagaki
NTT Open Source Software Center