On Fri, Oct 04, 2024 at 08:16:00PM +0800, jian he wrote:
> about v5 0001
> select_with_parens:
> '(' select_no_parens ')' { $$ = $2; }
> | '(' select_with_parens ')' { $$ = $2; }
> ;
>
>
> toplevel | calls | query
> ----------+-------+-------------------------------------------------------
> t | 1 | SELECT pg_stat_statements_reset() IS NOT NULL AS t
> t | 0 | SELECT toplevel, calls, query FROM pg_stat_statements+
> | | ORDER BY query COLLATE "C", toplevel
> t | 1 | explain (select $1)
> f | 1 | select $1);
>
> query "select $1);" looks weird. not sure how to improve it,
> or this should be the expected behavior?GOod point, this is confusing. The point is that having only stmt_location is not enough to detect where the element in the query you want to track is because it only points at its start location in the full query string. In an ideal world, what we should have is its start and end, pass it down to pgss_store(), and store only this subquery between the start and end positions in the stats entry. Making that right through the parser may be challenging, though. This concept is something that's perhaps larger than this thread? I think that we want the same kind of thing for values in IN() and ANY() clauses, where we want to track an area for a single normalization parameter, perhaps with a separate node_attr. I am not sure if using the same trackers would make sense, so I am just waving hands a bit here, but the concepts required are quite close. Saying that, a patch set implemented this way would ensure a strict 1:1 mapping between a query ID and the internal query in these EXPLAIN and CREATE commands, which would be good. The first step should be IMO to expand the tests of pgss and track all the behaviors we have historically in the tree about all that. Then, it becomes much easier to track how much we want to tweak them depending on if pgss.track is set to "top" or "all", and easier to see how a behavior changes when manipulating the parse node structures with location data. -- Michael
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