From 2b129bb6dadf74bb7edb4497da6e0cca983531ad Mon Sep 17 00:00:00 2001
From: Yao Feng <fengyao0087@gmail.com>
Date: Tue, 29 Sep 2026 09:09:20 +0000
Subject: [PATCH 2/2] Add specialized in-page search support for int8 (bigint)
 opclasses

Extend specialized in-page binary search and interpolation support to
single-column int8 (bigint) B-tree indexes.

This allows 64-bit integer index searches to bypass fmgr calling overhead
and leverage range interpolation, while demonstrating the modularity and
datatype-extensibility of the refactored specialized search framework.
---
 src/backend/access/nbtree/nbtcompare.c | 69 ++++++++++++++++++++++++++
 src/include/catalog/pg_amproc.dat      |  3 ++
 src/include/catalog/pg_proc.dat        |  3 ++
 3 files changed, 75 insertions(+)

diff --git a/src/backend/access/nbtree/nbtcompare.c b/src/backend/access/nbtree/nbtcompare.c
index 9685ecad9e3..0cc22f43dde 100644
--- a/src/backend/access/nbtree/nbtcompare.c
+++ b/src/backend/access/nbtree/nbtcompare.c
@@ -362,6 +362,75 @@ btint8sortsupport(PG_FUNCTION_ARGS)
 	PG_RETURN_VOID();
 }
 
+static inline bool
+btint8tuplevalue(IndexTuple itup, int64 *value)
+{
+	if (!bt_tuple_value_check(itup))
+		return false;
+
+	/* int8 is the first and only key, so its offset is fixed. */
+	memcpy(value, (char *) itup + sizeof(IndexTupleData), sizeof(*value));
+	return true;
+}
+
+static bool
+btint8pagecmp(BTScanInsert key, IndexTuple itup, int32 *result)
+{
+	ScanKey		skey = key->scankeys;
+	int64		search = DatumGetInt64(skey->sk_argument);
+	int64		value;
+
+	if (likely(btint8tuplevalue(itup, &value)))
+	{
+		if (skey->sk_flags & SK_BT_DESC)
+			*result = pg_cmp_s64(value, search);
+		else
+			*result = pg_cmp_s64(search, value);
+		return true;
+	}
+
+	return false;
+}
+
+/*
+ * Interpolation support for int8 single-column page search.
+ */
+static bool
+btint8interpolate(IndexTuple itup_low, IndexTuple itup_high,
+				  Datum target, bool desc, int nslots, int *offset)
+{
+	int64		lowval;
+	int64		highval;
+	int64		search;
+	double		span;
+	double		delta;
+
+	if (!btint8tuplevalue(itup_low, &lowval) ||
+		!btint8tuplevalue(itup_high, &highval) ||
+		lowval == highval)
+		return false;
+
+	search = DatumGetInt64(target);
+	span = desc ? (double) lowval - (double) highval : (double) highval - (double) lowval;
+	delta = desc ? (double) lowval - (double) search : (double) search - (double) lowval;
+
+	if (span <= 0.0 || delta < 0.0 || delta > span)
+		return false;
+
+	*offset = (int) ((delta * (double) nslots) / span);
+	return true;
+}
+
+Datum
+btint8binsearchsupport(PG_FUNCTION_ARGS)
+{
+	BTBinSearchSupportData *support =
+		(BTBinSearchSupportData *) PG_GETARG_POINTER(0);
+
+	support->compare_tuple = btint8pagecmp;
+	support->interpolate = btint8interpolate;
+	PG_RETURN_VOID();
+}
 
 static Datum
 int8_decrement(Relation rel, Datum existing, bool *underflow)
diff --git a/src/include/catalog/pg_amproc.dat b/src/include/catalog/pg_amproc.dat
index b2a413e9263..33ddfec4f3b 100644
--- a/src/include/catalog/pg_amproc.dat
+++ b/src/include/catalog/pg_amproc.dat
@@ -181,6 +181,9 @@
   amprocrighttype => 'int8', amprocnum => '4', amproc => 'btequalimage' },
 { amprocfamily => 'btree/integer_ops', amproclefttype => 'int8',
   amprocrighttype => 'int8', amprocnum => '6', amproc => 'btint8skipsupport' },
+{ amprocfamily => 'btree/integer_ops', amproclefttype => 'int8',
+  amprocrighttype => 'int8', amprocnum => '7',
+  amproc => 'btint8binsearchsupport' },
 { amprocfamily => 'btree/integer_ops', amproclefttype => 'int8',
   amprocrighttype => 'int4', amprocnum => '1', amproc => 'btint84cmp' },
 { amprocfamily => 'btree/integer_ops', amproclefttype => 'int8',
diff --git a/src/include/catalog/pg_proc.dat b/src/include/catalog/pg_proc.dat
index 12c39a57a51..372627e15ce 100644
--- a/src/include/catalog/pg_proc.dat
+++ b/src/include/catalog/pg_proc.dat
@@ -1028,6 +1028,9 @@
 { oid => '6404', descr => 'skip support',
   proname => 'btint8skipsupport', prorettype => 'void',
   proargtypes => 'internal', prosrc => 'btint8skipsupport' },
+{ oid => '8001', descr => 'binary search support',
+  proname => 'btint8binsearchsupport', prorettype => 'void',
+  proargtypes => 'internal', prosrc => 'btint8binsearchsupport' },
 { oid => '354', descr => 'less-equal-greater',
   proname => 'btfloat4cmp', proleakproof => 't', prorettype => 'int4',
   proargtypes => 'float4 float4', prosrc => 'btfloat4cmp' },
-- 
2.53.0