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Specialize tuplesort routines for different kinds of abbreviated keys

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Previously, the specialized tuplesort routine inlined handling for
reverse-sort and NULLs-ordering but called the datum comparator via a
pointer in the SortSupport struct parameter. Testing has showed that we
can get a useful performance gain by specializing datum comparison for
the different representations of abbreviated keys -- signed and unsigned
64-bit integers and signed 32-bit integers. Almost all abbreviatable data
types will benefit -- the only exception for now is numeric, since the
datum comparison is more complex. The performance gain depends on data
type and input distribution, but often falls in the range of 10-20% faster.

Thomas Munro

Reviewed by Peter Geoghegan, review and performance testing by me

Discussion:
https://www.postgresql.org/message-id/CA%2BhUKGKKYttZZk-JMRQSVak%3DCXSJ5fiwtirFf%3Dn%3DPAbumvn1Ww%40mail.gmail.com
This commit is contained in:
John Naylor
2022-04-02 15:22:25 +07:00
parent db086de5ab
commit 6974924347
10 changed files with 308 additions and 132 deletions
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22
src/backend/access/nbtree/nbtcompare.c
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@@ -119,26 +119,12 @@ btint4cmp(PG_FUNCTION_ARGS)
PG_RETURN_INT32(A_LESS_THAN_B);
}
static int
btint4fastcmp(Datum x, Datum y, SortSupport ssup)
{
int32 a = DatumGetInt32(x);
int32 b = DatumGetInt32(y);
if (a > b)
return A_GREATER_THAN_B;
else if (a == b)
return 0;
else
return A_LESS_THAN_B;
}
Datum
btint4sortsupport(PG_FUNCTION_ARGS)
{
SortSupport ssup = (SortSupport) PG_GETARG_POINTER(0);
ssup->comparator = btint4fastcmp;
ssup->comparator = ssup_datum_int32_cmp;
PG_RETURN_VOID();
}
@@ -156,6 +142,7 @@ btint8cmp(PG_FUNCTION_ARGS)
PG_RETURN_INT32(A_LESS_THAN_B);
}
#ifndef USE_FLOAT8_BYVAL
static int
btint8fastcmp(Datum x, Datum y, SortSupport ssup)
{
@@ -169,13 +156,18 @@ btint8fastcmp(Datum x, Datum y, SortSupport ssup)
else
return A_LESS_THAN_B;
}
#endif
Datum
btint8sortsupport(PG_FUNCTION_ARGS)
{
SortSupport ssup = (SortSupport) PG_GETARG_POINTER(0);
#ifdef USE_FLOAT8_BYVAL
ssup->comparator = ssup_datum_signed_cmp;
#else
ssup->comparator = btint8fastcmp;
#endif
PG_RETURN_VOID();
}