On Thu, 2024-06-20 at 17:07 +0700, John Naylor wrote: > On Sat, Jun 15, 2024 at 6:46 AM Jeff Davis <pg...@j-davis.com> wrote: > > Attached is a patch to use simplehash.h instead, which speeds > > things up > > enough to make them fairly close (from around 15% slower to around > > 8%). > > +#define SH_HASH_KEY(tb, key) hash_uint32((uint32) key) > > For a static inline hash for speed reasons, we can use murmurhash32 > here, which is also inline.
Thank you, that brings it down a few more percentage points. New patches attached, still based on the setlocale-removal patch series. Setup: create collation libc_c (provider=libc, locale='C'); create table collation_cache_test(t text); insert into collation_cache_test select g::text||' '||g::text from generate_series(1,200000000) g; Queries: select * from collation_cache_test where t < '0' collate "C"; select * from collation_cache_test where t < '0' collate libc_c; The two collations are identical except that the former benefits from the optimization for C_COLLATION_OID, and the latter does not, so these queries measure the overhead of the collation cache lookup. Results (in ms): "C" "libc_c" overhead master: 6350 7855 24% v4-0001: 6091 6324 4% (Note: I don't have an explanation for the difference in performance of the "C" locale -- probably just some noise in the test.) Considering that simplehash brings the worst case overhead under 5%, I don't see a big reason to use the single-element cache also. Regards, Jeff Davis
From 64a017f169858cf646002a28f97ae05cb7ab9fcd Mon Sep 17 00:00:00 2001 From: Jeff Davis <j...@j-davis.com> Date: Fri, 14 Jun 2024 15:38:42 -0700 Subject: [PATCH v4] Change collation cache to use simplehash.h. --- src/backend/utils/adt/pg_locale.c | 39 +++++++++++++++++++++---------- 1 file changed, 27 insertions(+), 12 deletions(-) diff --git a/src/backend/utils/adt/pg_locale.c b/src/backend/utils/adt/pg_locale.c index 2e6f624798f..5afb69c6632 100644 --- a/src/backend/utils/adt/pg_locale.c +++ b/src/backend/utils/adt/pg_locale.c @@ -57,12 +57,12 @@ #include "access/htup_details.h" #include "catalog/pg_collation.h" #include "catalog/pg_database.h" +#include "common/hashfn.h" #include "mb/pg_wchar.h" #include "miscadmin.h" #include "utils/builtins.h" #include "utils/formatting.h" #include "utils/guc_hooks.h" -#include "utils/hsearch.h" #include "utils/lsyscache.h" #include "utils/memutils.h" #include "utils/pg_locale.h" @@ -129,10 +129,27 @@ typedef struct { Oid collid; /* hash key: pg_collation OID */ pg_locale_t locale; /* locale_t struct, or 0 if not valid */ -} collation_cache_entry; -static HTAB *collation_cache = NULL; + /* needed for simplehash */ + uint32 hash; + char status; +} collation_cache_entry; +#define SH_PREFIX collation_cache +#define SH_ELEMENT_TYPE collation_cache_entry +#define SH_KEY_TYPE Oid +#define SH_KEY collid +#define SH_HASH_KEY(tb, key) murmurhash32((uint32) key) +#define SH_EQUAL(tb, a, b) (a == b) +#define SH_GET_HASH(tb, a) a->hash +#define SH_SCOPE static inline +#define SH_STORE_HASH +#define SH_DECLARE +#define SH_DEFINE +#include "lib/simplehash.h" + +static MemoryContext CollationCacheContext = NULL; +static collation_cache_hash *CollationCache = NULL; #if defined(WIN32) && defined(LC_MESSAGES) static char *IsoLocaleName(const char *); @@ -1219,18 +1236,16 @@ lookup_collation_cache(Oid collation) Assert(OidIsValid(collation)); Assert(collation != DEFAULT_COLLATION_OID); - if (collation_cache == NULL) + if (CollationCache == NULL) { - /* First time through, initialize the hash table */ - HASHCTL ctl; - - ctl.keysize = sizeof(Oid); - ctl.entrysize = sizeof(collation_cache_entry); - collation_cache = hash_create("Collation cache", 100, &ctl, - HASH_ELEM | HASH_BLOBS); + CollationCacheContext = AllocSetContextCreate(TopMemoryContext, + "collation cache", + ALLOCSET_DEFAULT_SIZES); + CollationCache = collation_cache_create( + CollationCacheContext, 16, NULL); } - cache_entry = hash_search(collation_cache, &collation, HASH_ENTER, &found); + cache_entry = collation_cache_insert(CollationCache, collation, &found); if (!found) { /* -- 2.34.1