Re: Row pattern recognition

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