On 7/26/24 11:00 PM, Jeff Davis wrote:
Results (in ms):
"C" "libc_c" overhead
master: 6350 7855 24%
v4-0001: 6091 6324 4%
I got more overhead in my quick benchmarking when I ran the same
benchmark. Also tried your idea with caching the last lookup (PoC patch
attached) and it basically removed all overhead, but I guess it will not
help if you have two different non.default locales in the same query.
"C" "libc_c" overhead
before: 6695 8376 25%
after: 6605 7340 11%
cache last: 6618 6677 1%
But even without that extra optimization I think this patch is worth
merging and the patch is small, simple and clean and easy to understand
and a just a clear speed up. Feels like a no brainer. I think that it is
ready for committer.
And then we can discuss after committing if an additional cache of the
last locale is worth it or not.
Andreas
From 5f634670569a3ef8249ff1747af2157b6939f505 Mon Sep 17 00:00:00 2001
From: Andreas Karlsson <andr...@proxel.se>
Date: Sun, 28 Jul 2024 00:04:43 +0200
Subject: [PATCH] WIP: Ugly caching of last locale
---
src/backend/utils/adt/pg_locale.c | 9 +++++++++
1 file changed, 9 insertions(+)
diff --git a/src/backend/utils/adt/pg_locale.c b/src/backend/utils/adt/pg_locale.c
index 4628fcd8dd..e0de7aa625 100644
--- a/src/backend/utils/adt/pg_locale.c
+++ b/src/backend/utils/adt/pg_locale.c
@@ -1566,6 +1566,9 @@ init_database_collation(void)
ReleaseSysCache(tup);
}
+static Oid last_collid = InvalidOid;
+static pg_locale_t last_locale = NULL;
+
/*
* Create a locale_t from a collation OID. Results are cached for the
* lifetime of the backend. Thus, do not free the result with freelocale().
@@ -1587,6 +1590,9 @@ pg_newlocale_from_collation(Oid collid)
if (collid == DEFAULT_COLLATION_OID)
return &default_locale;
+ if (collid == last_collid)
+ return last_locale;
+
cache_entry = lookup_collation_cache(collid);
if (cache_entry->locale == 0)
@@ -1712,6 +1718,9 @@ pg_newlocale_from_collation(Oid collid)
cache_entry->locale = resultp;
}
+ last_collid = collid;
+ last_locale = cache_entry->locale;
+
return cache_entry->locale;
}
--
2.43.0
