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help / color / mirror / Atom feedFrom: Baji Shaik <[email protected]>
To: [email protected]
Cc: [email protected]
Cc: [email protected]
Subject: [PATCH] Use ssup_datum_*_cmp for int2, oid, and oid8 sort support
Date: Wed, 3 Jun 2026 18:37:09 -0500
Message-ID: <CA+fm-RMyLC94NfrxCh273+dKs44U0ZJjRczznvzvgw=KtpPNVw@mail.gmail.com> (raw)
Hi,
While auditing nbtcompare.c, I noticed that int2, oid, and oid8
sortsupport functions use custom local fastcmp helpers that are
functionally equivalent to the existing ssup_datum_int32_cmp (for
int2) and ssup_datum_unsigned_cmp (for oid, oid8).
This prevents these types from hitting the radix sort fast path
added in commit ef3c3cf6d02 [1], which dispatches based on the
comparator function pointer.
The original 2021-2022 thread that introduced the ssup_datum_*_cmp
helpers (commit 6974924347c, Apr 2022) [2] covered int4, int8,
timestamp, date, and the abbreviated-key types (text, uuid, macaddr,
inet, bytea). int2 and oid weren't called out in that discussion,
and oid8 didn't exist at the time, it was added in Jan 2026 [3]
and inherited the custom fastcmp pattern from oid, about a month
before radix sort landed. This patch fills those gaps.
Switching to the existing helpers makes these types eligible for
radix sort. Benchmark (10M-row single-key sort):
Type Before After Speedup
---- ------ ----- -------
int2 2440 ms 1778 ms ~27%
oid 2875 ms 2073 ms ~28%
oid8 2837 ms 2042 ms ~28%
int4 -- 1765 ms (baseline)
int8 -- 2031 ms (baseline)
The patch just replaces the comparator assignment and removes the
now-unused local fastcmp functions. No behavioral change and the
helpers produce identical results.
int2 uses ssup_datum_int32_cmp because there is no int16-specific
helper, every int16 fits losslessly in int32, and int32_cmp is more
efficient than signed_cmp (4-byte radix passes instead of 8).
Other custom fastcmp users in core (float4/float8, varlena types)
cannot be trivially switched due to NaN handling or locale-dependent
comparison, so they are left as-is.
Tested with make check (245/245 pass) and make isolation/check
(128/128 pass).
[1]
https://git.postgresql.org/gitweb/?p=postgresql.git;a=commit;h=ef3c3cf6d02
[2]
https://www.postgresql.org/message-id/flat/CA%2BhUKGJ2-eaDqAum5bxhpMNhvuJmRDZxB_Tow0n-gse%2BHG0Yig%4...
[3] https://git.postgresql.org/gitweb/?p=postgresql.git;a=commit;h=b139bd3b6
Thanks,
Baji Shaik
Attachments:
[application/octet-stream] 0001-Use-ssup_datum_-_cmp-for-int2-oid-and-oid8-sort-supp.patch (2.6K, 3-0001-Use-ssup_datum_-_cmp-for-int2-oid-and-oid8-sort-supp.patch)
download | inline diff:
From e23fc1c9a28435f56cbb24e6fc23c85dde4062da Mon Sep 17 00:00:00 2001
From: Baji Shaik <[email protected]>
Date: Wed, 27 May 2026 01:48:05 +0000
Subject: [PATCH] Use ssup_datum_*_cmp for int2, oid and oid8 sort support
The int2, oid, and oid8 sortsupport functions used custom fastcmp
helpers that are functionally equivalent to ssup_datum_int32_cmp (for
int2) and ssup_datum_unsigned_cmp (for oid, oid8). This prevented
these types from using the radix sort fast path added in commit
ef3c3cf6d02, which dispatches based on the comparator pointer.
Switching to the existing helpers makes int2, oid, and oid8 column
sorts eligible for radix sort, bringing them to parity with int4/int8
baseline.
Author: Baji Shaik <[email protected]>
Reviewed-by:
Discussion:
---
src/backend/access/nbtree/nbtcompare.c | 43 ++------------------------
1 file changed, 3 insertions(+), 40 deletions(-)
diff --git a/src/backend/access/nbtree/nbtcompare.c b/src/backend/access/nbtree/nbtcompare.c
index 1d343377e98..795fded49d3 100644
--- a/src/backend/access/nbtree/nbtcompare.c
+++ b/src/backend/access/nbtree/nbtcompare.c
@@ -134,21 +134,12 @@ btint2cmp(PG_FUNCTION_ARGS)
PG_RETURN_INT32((int32) a - (int32) b);
}
-static int
-btint2fastcmp(Datum x, Datum y, SortSupport ssup)
-{
- int16 a = DatumGetInt16(x);
- int16 b = DatumGetInt16(y);
-
- return (int) a - (int) b;
-}
-
Datum
btint2sortsupport(PG_FUNCTION_ARGS)
{
SortSupport ssup = (SortSupport) PG_GETARG_POINTER(0);
- ssup->comparator = btint2fastcmp;
+ ssup->comparator = ssup_datum_int32_cmp;
PG_RETURN_VOID();
}
@@ -431,26 +422,12 @@ btoidcmp(PG_FUNCTION_ARGS)
PG_RETURN_INT32(A_LESS_THAN_B);
}
-static int
-btoidfastcmp(Datum x, Datum y, SortSupport ssup)
-{
- Oid a = DatumGetObjectId(x);
- Oid b = DatumGetObjectId(y);
-
- if (a > b)
- return A_GREATER_THAN_B;
- else if (a == b)
- return 0;
- else
- return A_LESS_THAN_B;
-}
-
Datum
btoidsortsupport(PG_FUNCTION_ARGS)
{
SortSupport ssup = (SortSupport) PG_GETARG_POINTER(0);
- ssup->comparator = btoidfastcmp;
+ ssup->comparator = ssup_datum_unsigned_cmp;
PG_RETURN_VOID();
}
@@ -513,26 +490,12 @@ btoid8cmp(PG_FUNCTION_ARGS)
PG_RETURN_INT32(A_LESS_THAN_B);
}
-static int
-btoid8fastcmp(Datum x, Datum y, SortSupport ssup)
-{
- Oid8 a = DatumGetObjectId8(x);
- Oid8 b = DatumGetObjectId8(y);
-
- if (a > b)
- return A_GREATER_THAN_B;
- else if (a == b)
- return 0;
- else
- return A_LESS_THAN_B;
-}
-
Datum
btoid8sortsupport(PG_FUNCTION_ARGS)
{
SortSupport ssup = (SortSupport) PG_GETARG_POINTER(0);
- ssup->comparator = btoid8fastcmp;
+ ssup->comparator = ssup_datum_unsigned_cmp;
PG_RETURN_VOID();
}
--
2.50.1
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