1 files changed, 29 insertions, 0 deletions
diff --git a/src/backend/access/gist/gistutil.c b/src/backend/access/gist/gistutil.c
index 8686735f234..d2d0b36d4ea 100644
--- a/src/backend/access/gist/gistutil.c
+++ b/src/backend/access/gist/gistutil.c
@@ -1069,3 +1069,32 @@ gist_stratnum_identity(PG_FUNCTION_ARGS)
 
 	PG_RETURN_UINT16(strat);
 }
+
+/*
+ * Returns the opclass's private stratnum used for the given strategy.
+ *
+ * Calls the opclass's GIST_STRATNUM_PROC support function, if any,
+ * and returns the result.
+ * Returns InvalidStrategy if the function is not defined.
+ */
+StrategyNumber
+GistTranslateStratnum(Oid opclass, StrategyNumber strat)
+{
+	Oid			opfamily;
+	Oid			opcintype;
+	Oid			funcid;
+	Datum		result;
+
+	/* Look up the opclass family and input datatype. */
+	if (!get_opclass_opfamily_and_input_type(opclass, &opfamily, &opcintype))
+		return InvalidStrategy;
+
+	/* Check whether the function is provided. */
+	funcid = get_opfamily_proc(opfamily, opcintype, opcintype, GIST_STRATNUM_PROC);
+	if (!OidIsValid(funcid))
+		return InvalidStrategy;
+
+	/* Ask the translation function */
+	result = OidFunctionCall1Coll(funcid, InvalidOid, UInt16GetDatum(strat));
+	return DatumGetUInt16(result);
+}