Create a "sort support" interface API for faster sorting.

This patch creates an API whereby a btree index opclass can optionally
provide non-SQL-callable support functions for sorting.  In the initial
patch, we only use this to provide a directly-callable comparator function,
which can be invoked with a bit less overhead than the traditional
SQL-callable comparator.  While that should be of value in itself, the real
reason for doing this is to provide a datatype-extensible framework for
more aggressive optimizations, as in Peter Geoghegan's recent work.

Robert Haas and Tom Lane

3 files changed, 79 insertions, 0 deletions

diff --git a/src/backend/utils/adt/date.c b/src/backend/utils/adt/date.c
index 271b57a830..ff4e3044f0 100644
--- a/src/backend/utils/adt/date.c
+++ b/src/backend/utils/adt/date.c
@@ -29,6 +29,7 @@
 #include "utils/date.h"
 #include "utils/datetime.h"
 #include "utils/nabstime.h"
+#include "utils/sortsupport.h"
 
 /*
  * gcc's -ffast-math switch breaks routines that expect exact results from
@@ -320,6 +321,28 @@ date_cmp(PG_FUNCTION_ARGS)
 	PG_RETURN_INT32(0);
 }
 
+static int
+date_fastcmp(Datum x, Datum y, SortSupport ssup)
+{
+	DateADT		a = DatumGetDateADT(x);
+	DateADT		b = DatumGetDateADT(y);
+
+	if (a < b)
+		return -1;
+	else if (a > b)
+		return 1;
+	return 0;
+}
+
+Datum
+date_sortsupport(PG_FUNCTION_ARGS)
+{
+	SortSupport	ssup = (SortSupport) PG_GETARG_POINTER(0);
+
+	ssup->comparator = date_fastcmp;
+	PG_RETURN_VOID();
+}
+
 Datum
 date_finite(PG_FUNCTION_ARGS)
 {
diff --git a/src/backend/utils/adt/float.c b/src/backend/utils/adt/float.c
index e3c84fd6c5..63b09a4eca 100644
--- a/src/backend/utils/adt/float.c
+++ b/src/backend/utils/adt/float.c
@@ -23,6 +23,7 @@
 #include "libpq/pqformat.h"
 #include "utils/array.h"
 #include "utils/builtins.h"
+#include "utils/sortsupport.h"
 
 
 #ifndef M_PI
@@ -936,6 +937,24 @@ btfloat4cmp(PG_FUNCTION_ARGS)
 	PG_RETURN_INT32(float4_cmp_internal(arg1, arg2));
 }
 
+static int
+btfloat4fastcmp(Datum x, Datum y, SortSupport ssup)
+{
+	float4		arg1 = DatumGetFloat4(x);
+	float4		arg2 = DatumGetFloat4(y);
+
+	return float4_cmp_internal(arg1, arg2);
+}
+
+Datum
+btfloat4sortsupport(PG_FUNCTION_ARGS)
+{
+	SortSupport	ssup = (SortSupport) PG_GETARG_POINTER(0);
+
+	ssup->comparator = btfloat4fastcmp;
+	PG_RETURN_VOID();
+}
+
 /*
  *		float8{eq,ne,lt,le,gt,ge}		- float8/float8 comparison operations
  */
@@ -1032,6 +1051,24 @@ btfloat8cmp(PG_FUNCTION_ARGS)
 	PG_RETURN_INT32(float8_cmp_internal(arg1, arg2));
 }
 
+static int
+btfloat8fastcmp(Datum x, Datum y, SortSupport ssup)
+{
+	float8		arg1 = DatumGetFloat8(x);
+	float8		arg2 = DatumGetFloat8(y);
+
+	return float8_cmp_internal(arg1, arg2);
+}
+
+Datum
+btfloat8sortsupport(PG_FUNCTION_ARGS)
+{
+	SortSupport	ssup = (SortSupport) PG_GETARG_POINTER(0);
+
+	ssup->comparator = btfloat8fastcmp;
+	PG_RETURN_VOID();
+}
+
 Datum
 btfloat48cmp(PG_FUNCTION_ARGS)
 {
diff --git a/src/backend/utils/adt/timestamp.c b/src/backend/utils/adt/timestamp.c
index 45e70029e5..450dcd4727 100644
--- a/src/backend/utils/adt/timestamp.c
+++ b/src/backend/utils/adt/timestamp.c
@@ -1830,6 +1830,25 @@ timestamp_cmp(PG_FUNCTION_ARGS)
 	PG_RETURN_INT32(timestamp_cmp_internal(dt1, dt2));
 }
 
+/* note: this is used for timestamptz also */
+static int
+timestamp_fastcmp(Datum x, Datum y, SortSupport ssup)
+{
+	Timestamp	a = DatumGetTimestamp(x);
+	Timestamp	b = DatumGetTimestamp(y);
+
+	return timestamp_cmp_internal(a, b);
+}
+
+Datum
+timestamp_sortsupport(PG_FUNCTION_ARGS)
+{
+	SortSupport	ssup = (SortSupport) PG_GETARG_POINTER(0);
+
+	ssup->comparator = timestamp_fastcmp;
+	PG_RETURN_VOID();
+}
+
 Datum
 timestamp_hash(PG_FUNCTION_ARGS)
 {