Re: proposal - queryid can be used as filter for auto_explain

Hello

+ PGC_SUSET | GUC_LIST_INPUT,
+ 0,

Shouldn't that be PGC_SUSET, GUC_LIST_INPUT?

+ /*
+ * In almost all cases, the queryid is computed due pg_stat_statements.
+ * Without log_queryids computing queryid is not necessary, but it can
+ * be hard to enable or disable queryid in dependecy of log_queryids.
+ * There are two possibilities - force queryid computing, or ignore
+ * queries without computed queryid (computing should be forced by setting
+ * compute_query_id). Boths probably can work, first looks more clean
+ * at this moment.
+ */
+ EnableQueryId();

This comment seems misleading to me. Based on it, I would think that
we always force queryid computing, but EnableQueryId doesn't do
anything with compute_query_id = off, so it seems like the second
choice instead? (also typo: Boths)

+ result = (auto_explain_queryids *) guc_malloc(LOG, allocsize);
+ if (result == NULL)
+ return false;

This leaks rawstring/elemlist, is that intentional?

+ if (*newval == NULL || *newval[0] == '\0')

That should be probably (*newval)[0].