Add sortsupport for gist_btree opclasses, for faster index builds.

Commit 16fa9b2 introduced a faster way to build GiST indexes, by
sorting all the data. This commit adds the sortsupport functions needed
to make use of that feature for btree_gist.

Author: Andrey Borodin
Discussion: https://www.postgresql.org/message-id/2F3F7265-0D22-44DB-AD71-8554C743D943@yandex-team.ru

Author: hlinnaka

contrib/btree_gist/Makefile

@@ -32,7 +32,7 @@ EXTENSION = btree_gist
 DATA = btree_gist--1.0--1.1.sql \
        btree_gist--1.1--1.2.sql btree_gist--1.2.sql btree_gist--1.2--1.3.sql \
        btree_gist--1.3--1.4.sql btree_gist--1.4--1.5.sql \
-       btree_gist--1.5--1.6.sql
+       btree_gist--1.5--1.6.sql btree_gist--1.6--1.7.sql
 PGFILEDESC = "btree_gist - B-tree equivalent GiST operator classes"
 
 REGRESS = init int2 int4 int8 float4 float8 cash oid timestamp timestamptz \

contrib/btree_gist/btree_bit.c

@@ -19,6 +19,7 @@ PG_FUNCTION_INFO_V1(gbt_bit_picksplit);
 PG_FUNCTION_INFO_V1(gbt_bit_consistent);
 PG_FUNCTION_INFO_V1(gbt_bit_penalty);
 PG_FUNCTION_INFO_V1(gbt_bit_same);
+PG_FUNCTION_INFO_V1(gbt_bit_sortsupport);
 
 
 /* define for comparison */
@@ -209,3 +210,27 @@ gbt_bit_penalty(PG_FUNCTION_ARGS)
 	PG_RETURN_POINTER(gbt_var_penalty(result, o, n, PG_GET_COLLATION(),
 									  &tinfo, fcinfo->flinfo));
 }
+
+static int
+gbt_bit_sort_build_cmp(Datum a, Datum b, SortSupport ssup)
+{
+	/* Use byteacmp(), like gbt_bitcmp() does */
+	return DatumGetInt32(DirectFunctionCall2(byteacmp,
+											 PointerGetDatum(a),
+											 PointerGetDatum(b)));
+}
+
+/*
+ * Sort support routine for fast GiST index build by sorting.
+ */
+Datum
+gbt_bit_sortsupport(PG_FUNCTION_ARGS)
+{
+	SortSupport ssup = (SortSupport) PG_GETARG_POINTER(0);
+
+	ssup->comparator = gbt_bit_sort_build_cmp;
+	ssup->abbrev_converter = NULL;
+	ssup->abbrev_abort = NULL;
+	ssup->abbrev_full_comparator = NULL;
+	PG_RETURN_VOID();
+}