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Re: Row pattern recognition

Tatsuo Ishii <ishii@postgresql.org>

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From: Tatsuo Ishii <ishii@postgresql.org>
To: assam258@gmail.com
Cc: jacob.champion@enterprisedb.com, david.g.johnston@gmail.com, vik@postgresfriends.org, er@xs4all.nl, peter@eisentraut.org, pgsql-hackers@postgresql.org
Date: 2026-01-20T03:14:45Z
Lists: pgsql-hackers 
> Hi Ishii-san,
> 
> While reviewing the code, I noticed a potential improvement
> in 'register_reduced_frame_map()':
> 
> diff --git a/src/backend/executor/nodeWindowAgg.c
> b/src/backend/executor/nodeWindowAgg.c
> index 5185ad40237..3a71c279945 100644
> --- a/src/backend/executor/nodeWindowAgg.c
> +++ b/src/backend/executor/nodeWindowAgg.c
> @@ -4770,7 +4770,7 @@ register_reduced_frame_map(WindowAggState *winstate,
> int64 pos, int val)
>         if (pos < 0)
>                 elog(ERROR, "wrong pos: " INT64_FORMAT, pos);
> 
> -       if (pos > winstate->alloc_sz - 1)
> +       while (pos > winstate->alloc_sz - 1)
>         {
>                 realloc_sz = winstate->alloc_sz * 2;
> 
> In practice, 'pos' is always sequential (0, 1, 2, ...),
> so the current 'if' works fine - doubling once is always
> sufficient for +1 increment.
> 
> However, using 'while' would be more defensive, handling
> any theoretical case where 'pos' might jump by more than
> 2x the current size.
> 
> It's a trivial change with no functional impact on normal
> operation, but makes the code more robust.
> 
> What do you think?

Looks good improvement to me. Will merge into v41.

Best regards,
--
Tatsuo Ishii
SRA OSS K.K.
English: http://www.sraoss.co.jp/index_en/
Japanese:http://www.sraoss.co.jp

Commits

Same data as JSON: GET /api/v1/messages/:b64id/commits the thread's linked commits as JSON, with link sources. API reference →

  1. Adjust cross-version upgrade tests for seg_out() fix

  2. Rationalize error comments in partition split/merge tests

  3. Add fast path for foreign key constraint checks

  4. Fix assorted pretty-trivial memory leaks in the backend.

  5. Add temporal FOREIGN KEY contraints

  6. Add trailing commas to enum definitions

  7. Remove obsolete executor cleanup code