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Save a few bytes per CatCTup.

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CatalogCacheCreateEntry() computed the space needed for a CatCTup
as sizeof(CatCTup) + MAXIMUM_ALIGNOF.  That's not our usual style,
and it wastes memory by allocating more padding than necessary.
On 64-bit machines sizeof(CatCTup) would be maxaligned already
since it contains pointer fields, therefore this code is wasting
8 bytes compared to the more usual MAXALIGN(sizeof(CatCTup)).

While at it, we don't really need to do MemoryContextSwitchTo()
when we're only allocating one block.

Author: ChangAo Chen <cca5507@qq.com>
Reviewed-by: Tom Lane <tgl@sss.pgh.pa.us>
Discussion: https://postgr.es/m/tencent_A42E0544C6184FE940CD8E3B14A3F0A39605@qq.com
This commit is contained in:
Tom Lane 2026-03-15 18:05:38 -04:00
parent bb53b8d359
commit e5a77d876d
1 changed files with 4 additions and 6 deletions
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10
src/backend/utils/cache/catcache.c vendored
View file

@ -2221,20 +2221,18 @@ CatalogCacheCreateEntry(CatCache *cache, HeapTuple ntp, Datum *arguments,
dtp = ntp;
/* Allocate memory for CatCTup and the cached tuple in one go */
oldcxt = MemoryContextSwitchTo(CacheMemoryContext);
ct = (CatCTup *) palloc(sizeof(CatCTup) +
MAXIMUM_ALIGNOF + dtp->t_len);
ct = (CatCTup *)
MemoryContextAlloc(CacheMemoryContext,
MAXALIGN(sizeof(CatCTup)) + dtp->t_len);
ct->tuple.t_len = dtp->t_len;
ct->tuple.t_self = dtp->t_self;
ct->tuple.t_tableOid = dtp->t_tableOid;
ct->tuple.t_data = (HeapTupleHeader)
MAXALIGN(((char *) ct) + sizeof(CatCTup));
(((char *) ct) + MAXALIGN(sizeof(CatCTup)));
/* copy tuple contents */
memcpy((char *) ct->tuple.t_data,
(const char *) dtp->t_data,
dtp->t_len);
MemoryContextSwitchTo(oldcxt);
if (dtp != ntp)
heap_freetuple(dtp);