logical: do not allow the REFCURSOR type

This removes LDR support for the REFCURSOR type. The crud writer does
not support it because REFCURSOR does not support the equality SQL
operator.

This removal is unlikely to impact any users. The REFCURSOR is a weird
type that should not show up in a durable table. If the user really
needs this type for some reason, they could store they type as a STRING
and convert it back to a REFCURSOR when reading from the table.

Epic: CRDB-48647
Release note: none

Author: jeffswenson

pkg/crosscluster/logical/logical_replication_job_test.go

@@ -2833,6 +2833,11 @@ func TestLogicalReplicationCreationChecks(t *testing.T) {
 	jobutils.WaitForJobToCancel(t, dbA, jobAID)
 	replicationtestutils.WaitForAllProducerJobsToFail(t, dbB)
 
+	// Check that REFCURSOR columns are not allowed.
+	dbA.Exec(t, "CREATE TABLE tab_with_refcursor (pk INT PRIMARY KEY, curs REFCURSOR)")
+	dbB.Exec(t, "CREATE TABLE b.tab_with_refcursor (pk INT PRIMARY KEY, curs REFCURSOR)")
+	expectErr(t, "tab_with_refcursor", "cannot create logical replication stream: column curs is a RefCursor")
+
 	// Add different default values to to the source and dest, verify the stream
 	// can be created, and that the default value is sent over the wire.
 	dbA.Exec(t, "CREATE TABLE tab2 (pk INT PRIMARY KEY, payload STRING DEFAULT 'cat')")

pkg/sql/catalog/tabledesc/logical_replication_helpers.go

@@ -58,6 +58,22 @@ func CheckLogicalReplicationCompatibility(
 		return pgerror.Wrapf(err, pgcode.InvalidTableDefinition, cannotLDRMsg)
 	}
 
+	if err := checkForbiddenTypes(dst); err != nil {
+		return pgerror.Wrapf(err, pgcode.InvalidTableDefinition, cannotLDRMsg)
+	}
+
+	return nil
+}
+
+func checkForbiddenTypes(dst *descpb.TableDescriptor) error {
+	for _, col := range dst.Columns {
+		// RefCursor is not supported by LDR because it has no definition of
+		// equality. It's a weird type that should never exist in a durable table
+		// since a cursor is a session scoped entity.
+		if col.Type.Family() == types.RefCursorFamily {
+			return errors.Newf("column %s is a RefCursor", col.Name)
+		}
+	}
 	return nil
 }