Re: Memory leak in pg_stat_statements when qtext file contains invalid encoding

On 27/03/2026 11:05, Daniel Gustafsson wrote:
>> On 27 Mar 2026, at 09:59, Heikki Linnakangas <hlinnaka@iki.fi> wrote:
> 
>> Hmm, perhaps. But there's a simpler, less invasive fix. When that code was written, we didn't have MCXT_ALLOC_HUGE
norMCXT_ALLOC_NO_OOM. Now that we do, we can just use palloc_extended(MCXT_ALLOC_HUGE | MCXT_ALLOC_NO_OOM) instead of
rawmalloc(). Per attached.
 
> 
> LGTM.

Committed, thanks!


Here's one way to reproduce the invalid encoding error without 
artificially corrupting the file:

-- Run a query with a non-latin character in it. (This needs to be run 
in UTF-8 database.)
psql postgres -c 'select g as "omega Ω col" from generate_series(1, 1) g;'

-- Create a database with latin1 encoding
psql postgres -c "create database latindb encoding 'latin1' lc_ctype='C' 
lc_collate='C' template template0"

-- check pg_stat_statements() from the latin1 database
-- This fails with encoding conversion error.
PATH=~/pgsql.fsmfork/bin/ psql latindb -c "create extension 
pg_stat_statements; select * from pg_stat_statements"

If you repeat the erroring "select * from pg_stat_statements" in latindb 
many times, you can see the memory usage grow without this fix.

- Heikki