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Re: Row pattern recognition

Henson Choi <assam258@gmail.com>

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From: Henson Choi <assam258@gmail.com>
To: Tatsuo Ishii <ishii@postgresql.org>
Cc: jacob.champion@enterprisedb.com, david.g.johnston@gmail.com, vik@postgresfriends.org, er@xs4all.nl, peter@eisentraut.org, pgsql-hackers@postgresql.org
Date: 2026-01-20T02:29:34Z
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?

Best regards

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