1 files changed, 61 insertions, 0 deletions
diff --git a/src/backend/utils/adt/skipsupport.c b/src/backend/utils/adt/skipsupport.c
new file mode 100644
index 00000000000..2bd35d2d272
--- /dev/null
+++ b/src/backend/utils/adt/skipsupport.c
@@ -0,0 +1,61 @@
+/*-------------------------------------------------------------------------
+ *
+ * skipsupport.c
+ *	  Support routines for B-Tree skip scan.
+ *
+ *
+ * Portions Copyright (c) 1996-2025, PostgreSQL Global Development Group
+ * Portions Copyright (c) 1994, Regents of the University of California
+ *
+ * IDENTIFICATION
+ *	  src/backend/utils/adt/skipsupport.c
+ *
+ *-------------------------------------------------------------------------
+ */
+
+#include "postgres.h"
+
+#include "access/nbtree.h"
+#include "utils/lsyscache.h"
+#include "utils/skipsupport.h"
+
+/*
+ * Fill in SkipSupport given an operator class (opfamily + opcintype).
+ *
+ * On success, returns skip support struct, allocating in caller's memory
+ * context.  Otherwise returns NULL, indicating that operator class has no
+ * skip support function.
+ */
+SkipSupport
+PrepareSkipSupportFromOpclass(Oid opfamily, Oid opcintype, bool reverse)
+{
+	Oid			skipSupportFunction;
+	SkipSupport sksup;
+
+	/* Look for a skip support function */
+	skipSupportFunction = get_opfamily_proc(opfamily, opcintype, opcintype,
+											BTSKIPSUPPORT_PROC);
+	if (!OidIsValid(skipSupportFunction))
+		return NULL;
+
+	sksup = palloc(sizeof(SkipSupportData));
+	OidFunctionCall1(skipSupportFunction, PointerGetDatum(sksup));
+
+	if (reverse)
+	{
+		/*
+		 * DESC/reverse case: swap low_elem with high_elem, and swap decrement
+		 * with increment
+		 */
+		Datum		low_elem = sksup->low_elem;
+		SkipSupportIncDec decrement = sksup->decrement;
+
+		sksup->low_elem = sksup->high_elem;
+		sksup->decrement = sksup->increment;
+
+		sksup->high_elem = low_elem;
+		sksup->increment = decrement;
+	}
+
+	return sksup;
+}