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Fix misleading comment in tuplesort.c

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A comment in tuplesort.c was claiming that the code was defining
INITIAL_MEMTUPSIZE so that it *does not* exceed
ALLOCSET_SEPARATE_THRESHOLD, but the code actually ensures that we
purposefully *do* exceed ALLOCSET_SEPARATE_THRESHOLD for the initial
allocation of the tuples array, as per reasons detailed in the
commentary of grow_memtuples().

Also, there's not much need to repeat the mention about
ALLOCSET_SEPARATE_THRESHOLD in each location where INITIAL_MEMTUPSIZE is
used, so remove those comments.

Author: ChangAo Chen <cca5507@qq.com>
Reviewed-by: Chao Li <li.evan.chao@gmail.com>
Reviewed-by: David G. Johnston <david.g.johnston@gmail.com>
Discussion: https://postgr.es/m/tencent_6FA14F85D6B5B5291532D6789E07F4765C08%40qq.com
This commit is contained in:
David Rowley
2025-12-10 12:01:14 +13:00
parent 1b105f9472
commit f275afc997
1 changed files with 3 additions and 13 deletions
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16
src/backend/utils/sort/tuplesort.c
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@@ -111,11 +111,9 @@
#include "utils/tuplesort.h"
/*
* Initial size of memtuples array. We're trying to select this size so that
* array doesn't exceed ALLOCSET_SEPARATE_THRESHOLD and so that the overhead of
* allocation might possibly be lowered. However, we don't consider array sizes
* less than 1024.
*
* Initial size of memtuples array. This must be more than
* ALLOCSET_SEPARATE_THRESHOLD; see comments in grow_memtuples(). Clamp at
* 1024 elements to avoid excessive reallocs.
*/
#define INITIAL_MEMTUPSIZE Max(1024, \
ALLOCSET_SEPARATE_THRESHOLD / sizeof(SortTuple) + 1)
@@ -692,10 +690,6 @@ tuplesort_begin_common(int workMem, SortCoordinate coordinate, int sortopt)
state->base.sortcontext = sortcontext;
state->base.maincontext = maincontext;
/*
* Initial size of array must be more than ALLOCSET_SEPARATE_THRESHOLD;
* see comments in grow_memtuples().
*/
state->memtupsize = INITIAL_MEMTUPSIZE;
state->memtuples = NULL;
@@ -784,10 +778,6 @@ tuplesort_begin_batch(Tuplesortstate *state)
state->memtupcount = 0;
/*
* Initial size of array must be more than ALLOCSET_SEPARATE_THRESHOLD;
* see comments in grow_memtuples().
*/
state->growmemtuples = true;
state->slabAllocatorUsed = false;
if (state->memtuples != NULL && state->memtupsize != INITIAL_MEMTUPSIZE)