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* [PATCH v6 3/3] Optimize hash function
@ 2021-01-20 22:06 Heikki Linnakangas <[email protected]>
0 siblings, 0 replies; 5+ messages in thread
From: Heikki Linnakangas @ 2021-01-20 22:06 UTC (permalink / raw)
---
src/backend/utils/resowner/resowner.c | 24 ++++++++++++++++++------
src/include/common/hashfn.h | 15 +++++++++++++++
2 files changed, 33 insertions(+), 6 deletions(-)
diff --git a/src/backend/utils/resowner/resowner.c b/src/backend/utils/resowner/resowner.c
index 1db1e7cf14b..72e4d8a784c 100644
--- a/src/backend/utils/resowner/resowner.c
+++ b/src/backend/utils/resowner/resowner.c
@@ -163,15 +163,27 @@ static void ReleaseAuxProcessResourcesCallback(int code, Datum arg);
* INTERNAL ROUTINES *
*****************************************************************************/
+/*
+ * Hash function for value+kind combination.
+ */
static inline uint32
hash_resource_elem(Datum value, ResourceOwnerFuncs *kind)
{
- Datum data[2];
-
- data[0] = value;
- data[1] = PointerGetDatum(kind);
-
- return hash_bytes((unsigned char *) &data, 2 * SIZEOF_DATUM);
+ /*
+ * Most resources types store a pointer in 'value', and pointers are
+ * unique all on their own. But some resources store plain integers (Files
+ * and Buffers as of this writing), so we want to incorporate the 'kind'
+ * in the hash too, otherwise those resources will collide a lot. But
+ * because there are only a few resource kinds like that - and only a few
+ * resource kinds to begin with - we don't need to work too hard to mix
+ * 'kind' into the hash. Just add it with hash_combine(), it perturbs the
+ * result enough for our purposes.
+ */
+#if SIZEOF_DATUM == 8
+ return hash_combine64(murmurhash64((uint64) value), (uint64) kind);
+#else
+ return hash_combine(murmurhash32((uint32) value), (uint32) kind);
+#endif
}
static void
diff --git a/src/include/common/hashfn.h b/src/include/common/hashfn.h
index c634cc067a1..009ffbbdd38 100644
--- a/src/include/common/hashfn.h
+++ b/src/include/common/hashfn.h
@@ -101,4 +101,19 @@ murmurhash32(uint32 data)
return h;
}
+/* 64-bit variant */
+static inline uint64
+murmurhash64(uint64 data)
+{
+ uint64 h = data;
+
+ h ^= h >> 33;
+ h *= 0xff51afd7ed558ccd;
+ h ^= h >> 33;
+ h *= 0xc4ceb9fe1a85ec53;
+ h ^= h >> 33;
+
+ return h;
+}
+
#endif /* HASHFN_H */
--
2.29.2
--------------F30A5443A5D524A5CBC51AE7
Content-Type: text/x-patch; charset=UTF-8;
name="v2-0001-resownerbench.patch"
Content-Transfer-Encoding: 7bit
Content-Disposition: attachment;
filename="v2-0001-resownerbench.patch"
^ permalink raw reply [nested|flat] 5+ messages in thread
* How to add a new pg oid?
@ 2023-09-05 14:29 jacktby jacktby <[email protected]>
0 siblings, 1 reply; 5+ messages in thread
From: jacktby jacktby @ 2023-09-05 14:29 UTC (permalink / raw)
To: [email protected]
^ permalink raw reply [nested|flat] 5+ messages in thread
* Re: How to add a new pg oid?
@ 2023-09-05 17:47 David G. Johnston <[email protected]>
parent: jacktby jacktby <[email protected]>
0 siblings, 1 reply; 5+ messages in thread
From: David G. Johnston @ 2023-09-05 17:47 UTC (permalink / raw)
To: jacktby jacktby <[email protected]>; +Cc: [email protected]
OIDs don't exist independently of the data they are associated with. Give
more context if you want a better answer. Or just go look at the source
code commits for when the last time something needing an OID got added to
the core catalog.
David J.
^ permalink raw reply [nested|flat] 5+ messages in thread
* Re: How to add a new pg oid?
@ 2023-09-06 10:19 jacktby jacktby <[email protected]>
parent: David G. Johnston <[email protected]>
0 siblings, 1 reply; 5+ messages in thread
From: jacktby jacktby @ 2023-09-06 10:19 UTC (permalink / raw)
To: [email protected]; +Cc: David G. Johnston <[email protected]>
> 2023年9月6日 01:47，David G. Johnston <[email protected]> 写道：
>
> OIDs don't exist independently of the data they are associated with. Give more context if you want a better answer. Or just go look at the source code commits for when the last time something needing an OID got added to the core catalog.
>
> David J.
>
{ oid => '111', array_type_oid => '6099', descr => 'similarity columns',
typname => 'similarity_columns', typlen => '-1', typlen => '-1', typbyval => 'f', typcategory => 'U',
typinput => 'byteain', typoutput => 'byteaout', typreceive => 'bytearecv',
typsend => 'byteasend', typalign => 'i', typstorage => 'x' },
I add above into pg_type.dat. And then I add execute “make install” and restart pg. And Then do below:
postgres=# SELECT typname from pg_type where typname like '%similarity%';
typname
---------
(0 rows)
I can’t get the type I added. What else I need to do?
^ permalink raw reply [nested|flat] 5+ messages in thread
* Re: How to add a new pg oid?
@ 2023-09-06 10:50 jacktby jacktby <[email protected]>
parent: jacktby jacktby <[email protected]>
0 siblings, 0 replies; 5+ messages in thread
From: jacktby jacktby @ 2023-09-06 10:50 UTC (permalink / raw)
To: [email protected]
> 2023年9月6日 18:19，jacktby jacktby <[email protected]> 写道：
>
>
>
>> 2023年9月6日 01:47，David G. Johnston <[email protected]> 写道：
>>
>> OIDs don't exist independently of the data they are associated with. Give more context if you want a better answer. Or just go look at the source code commits for when the last time something needing an OID got added to the core catalog.
>>
>> David J.
>>
>
> { oid => '111', array_type_oid => '6099', descr => 'similarity columns',
> typname => 'similarity_columns', typlen => '-1', typlen => '-1', typbyval => 'f', typcategory => 'U',
> typinput => 'byteain', typoutput => 'byteaout', typreceive => 'bytearecv',
> typsend => 'byteasend', typalign => 'i', typstorage => 'x' },
>
> I add above into pg_type.dat. And then I add execute “make install” and restart pg. And Then do below:
> postgres=# SELECT typname from pg_type where typname like '%similarity%';
> typname
> ---------
> (0 rows)
>
> I can’t get the type I added. What else I need to do?
I add below in bootstrap.c:
static const struct typinfo TypInfo[] = {
{"similarity_columns", SimilarityColumns, 0, -1, false, TYPALIGN_INT, TYPSTORAGE_EXTENDED, InvalidOid,
F_BYTEAIN, F_BYTEAOUT},
….
}
And then “make install” and restart pg.but still:
postgres=# SELECT typname from pg_type where typname like '%similarity%';
typname
---------
(0 rows)
Please give me help.
^ permalink raw reply [nested|flat] 5+ messages in thread
end of thread, other threads:[~2023-09-06 10:50 UTC | newest]
Thread overview: 5+ messages (download: mbox mbox.gz follow: Atom feed)
-- links below jump to the message on this page --
2021-01-20 22:06 [PATCH v6 3/3] Optimize hash function Heikki Linnakangas <[email protected]>
2023-09-05 14:29 How to add a new pg oid? jacktby jacktby <[email protected]>
2023-09-05 17:47 ` Re: How to add a new pg oid? David G. Johnston <[email protected]>
2023-09-06 10:19 ` Re: How to add a new pg oid? jacktby jacktby <[email protected]>
2023-09-06 10:50 ` Re: How to add a new pg oid? jacktby jacktby <[email protected]>
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