diff options
| author | David Rowley | 2025-12-09 23:01:14 +0000 |
|---|---|---|
| committer | David Rowley | 2025-12-09 23:01:14 +0000 |
| commit | f275afc997d77ada991307d22703b08f1dedef13 (patch) | |
| tree | 267b5ccd8e12e9f0926c8d1ac8b36569dcffdaac | |
| parent | 1b105f9472bdb9a68f709778afafb494997267bd (diff) | |
Fix misleading comment in tuplesort.c
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
| -rw-r--r-- | src/backend/utils/sort/tuplesort.c | 16 |
1 files changed, 3 insertions, 13 deletions
diff --git a/src/backend/utils/sort/tuplesort.c b/src/backend/utils/sort/tuplesort.c index c1fa7a97509..88ae529e843 100644 --- a/src/backend/utils/sort/tuplesort.c +++ b/src/backend/utils/sort/tuplesort.c @@ -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) |