Per-column collation support

This adds collation support for columns and domains, a COLLATE clause
to override it per expression, and B-tree index support.

Peter Eisentraut
reviewed by Pavel Stehule, Itagaki Takahiro, Robert Haas, Noah Misch

2 files changed, 69 insertions, 1 deletions

diff --git a/src/backend/utils/fmgr/fmgr.c b/src/backend/utils/fmgr/fmgr.c
index 54d50e96377..d05e4d2dd8f 100644
--- a/src/backend/utils/fmgr/fmgr.c
+++ b/src/backend/utils/fmgr/fmgr.c
@@ -192,6 +192,7 @@ fmgr_info_cxt_security(Oid functionId, FmgrInfo *finfo, MemoryContext mcxt,
 	 * elogs.
 	 */
 	finfo->fn_oid = InvalidOid;
+	finfo->fn_collation = InvalidOid;
 	finfo->fn_extra = NULL;
 	finfo->fn_mcxt = mcxt;
 	finfo->fn_expr = NULL;		/* caller may set this later */
@@ -420,6 +421,25 @@ fmgr_info_other_lang(Oid functionId, FmgrInfo *finfo, HeapTuple procedureTuple)
 }
 
 /*
+ * Initialize the fn_collation field
+ */
+void
+fmgr_info_collation(Oid collationId, FmgrInfo *finfo)
+{
+	finfo->fn_collation = collationId;
+}
+
+/*
+ * Initialize the fn_expr field and set the collation based on it
+ */
+void
+fmgr_info_expr(Node *expr, FmgrInfo *finfo)
+{
+	finfo->fn_expr = expr;
+	finfo->fn_collation = exprCollation(expr);
+}
+
+/*
  * Fetch and validate the information record for the given external function.
  * The function is specified by a handle for the containing library
  * (obtained from load_external_function) as well as the function name.
@@ -1273,6 +1293,52 @@ DirectFunctionCall9(PGFunction func, Datum arg1, Datum arg2,
 	return result;
 }
 
+Datum
+DirectFunctionCall1WithCollation(PGFunction func, Oid collation, Datum arg1)
+{
+	FunctionCallInfoData fcinfo;
+	FmgrInfo	flinfo;
+	Datum		result;
+
+	InitFunctionCallInfoData(fcinfo, &flinfo, 1, NULL, NULL);
+	fcinfo.flinfo->fn_collation = collation;
+
+	fcinfo.arg[0] = arg1;
+	fcinfo.argnull[0] = false;
+
+	result = (*func) (&fcinfo);
+
+	/* Check for null result, since caller is clearly not expecting one */
+	if (fcinfo.isnull)
+		elog(ERROR, "function %p returned NULL", (void *) func);
+
+	return result;
+}
+
+Datum
+DirectFunctionCall2WithCollation(PGFunction func, Oid collation, Datum arg1, Datum arg2)
+{
+	FunctionCallInfoData fcinfo;
+	FmgrInfo	flinfo;
+	Datum		result;
+
+	InitFunctionCallInfoData(fcinfo, &flinfo, 2, NULL, NULL);
+	fcinfo.flinfo->fn_collation = collation;
+
+	fcinfo.arg[0] = arg1;
+	fcinfo.arg[1] = arg2;
+	fcinfo.argnull[0] = false;
+	fcinfo.argnull[1] = false;
+
+	result = (*func) (&fcinfo);
+
+	/* Check for null result, since caller is clearly not expecting one */
+	if (fcinfo.isnull)
+		elog(ERROR, "function %p returned NULL", (void *) func);
+
+	return result;
+}
+
 
 /*
  * These are for invocation of a previously-looked-up function with a
diff --git a/src/backend/utils/fmgr/funcapi.c b/src/backend/utils/fmgr/funcapi.c
index e32c716392c..321b4e7f8ff 100644
--- a/src/backend/utils/fmgr/funcapi.c
+++ b/src/backend/utils/fmgr/funcapi.c
@@ -468,7 +468,6 @@ resolve_polymorphic_tupdesc(TupleDesc tupdesc, oidvector *declared_args,
 	/* If nothing found, parser messed up */
 	if (!OidIsValid(anyelement_type) && !OidIsValid(anyarray_type))
 		return false;
-
 	/* If needed, deduce one polymorphic type from the other */
 	if (have_anyelement_result && !OidIsValid(anyelement_type))
 		anyelement_type = resolve_generic_type(ANYELEMENTOID,
@@ -511,6 +510,9 @@ resolve_polymorphic_tupdesc(TupleDesc tupdesc, oidvector *declared_args,
 			default:
 				break;
 		}
+		/* Set collation based on actual argument types */
+		TupleDescInitEntryCollation(tupdesc, i + 1,
+									exprCollation(call_expr));
 	}
 
 	return true;