Re: Prevent internal error at concurrent CREATE OR REPLACE FUNCTION

Hi,

On Thu, 22 May 2025 10:25:58 +0800
jian he <jian(dot)universality(at)gmail(dot)com> wrote:

Thank you for looking into it.

> + /* Lock the function so nobody else can do anything with it. */
> + LockDatabaseObject(ProcedureRelationId, oldproc->oid, 0, AccessExclusiveLock);
> +
> + /*
> + * It is possible that by the time we acquire the lock on function,
> + * concurrent DDL has removed it. We can test this by checking the
> + * existence of function. We get the tuple again to avoid the risk
> + * of function definition getting changed.
> + */
> + oldtup = SearchSysCacheCopy3(PROCNAMEARGSNSP,
> + PointerGetDatum(procedureName),
> + PointerGetDatum(parameterTypes),
> + ObjectIdGetDatum(procNamespace));
>
> we already called LockDatabaseObject, concurrent DDL can
> not do DROP FUNCTION or ALTER FUNCTION.
> so no need to call SearchSysCacheCopy3 again?

The function may be dropped *before* we call LockDatabaseObject.
SearchSysCacheCopy3 is called for check this.
Plese see AlterPublication() as a similar code example.

>
> @@ -553,11 +575,13 @@ ProcedureCreate(const char *procedureName,
> replaces[Anum_pg_proc_proowner - 1] = false;
> replaces[Anum_pg_proc_proacl - 1] = false;
>
> +
> +
> /* Okay, do it... */
> no need to add these two new lines.

I'll remove the lines. Thanks.

Regards,
Yugo Nagata

--
Yugo Nagata <nagata(at)sraoss(dot)co(dot)jp>