Thread

Re: Fixes a clip bug in pg_stat_get_backend_activity()

Michael Paquier <michael@paquier.xyz> — 2025-12-26T05:59:33Z

On Fri, Dec 26, 2025 at 11:54:38AM +0800, Chao Li wrote:
> This is an eyeball caught bug:
> ```
>  clipped_activity = pgstat_clip_activity(activity);
> ret = cstring_to_text(activity); <== bug here: should use clipped_activity
> pfree(clipped_activity);
> 
> PG_RETURN_TEXT_P(ret);
> ```
> clipped result is stored in clipped_activity, but it's not used.

Ohh....  Oops.  Nice catch.

> This should be an edge case bug. It would only be triggered by using
> multi-byte characters in SQL and the SQL statement length
> exceeds track_activity_query_size, and a multi-byte character just across
> the boundary and gets truncated in the middle.

Yep, that seems wrong since 54b6cd589ac2, meaning a backpatch all the
way down.  pg_stat_get_backend_activity() is a less popular solution
than pg_stat_activity, so this would unlikely be hit, still wrong it
is.
--
Michael