logical: enable crud writer by default

This change enables the crud writer by default for IMMEDIATE and
VALIDATED mode LDR jobs.

Release note: LDR now supports partial indexes and is tolerant of
mismatched column ids in the source and destination tables.

Epic: CRDB-51533

Author: jeffswenson

pkg/crosscluster/logical/logical_replication_job_test.go

@@ -22,6 +22,7 @@ import (
 	"github.com/cockroachdb/cockroach/pkg/base"
 	"github.com/cockroachdb/cockroach/pkg/ccl/changefeedccl/cdcevent"
 	"github.com/cockroachdb/cockroach/pkg/clusterversion"
+	"github.com/cockroachdb/cockroach/pkg/crosscluster"
 	"github.com/cockroachdb/cockroach/pkg/crosscluster/replicationtestutils"
 	"github.com/cockroachdb/cockroach/pkg/crosscluster/streamclient"
 	_ "github.com/cockroachdb/cockroach/pkg/crosscluster/streamclient/randclient"
@@ -895,9 +896,6 @@ func TestRandomTables(t *testing.T) {
 	tc, s, runnerA, runnerB := setupLogicalTestServer(t, ctx, testClusterBaseClusterArgs, 1)
 	defer tc.Stopper().Stop(ctx)
 
-	// TODO(#148303): Remove this once the crud writer supports tables with array primary keys.
-	runnerA.Exec(t, "SET CLUSTER SETTING logical_replication.consumer.immediate_mode_writer = 'legacy-kv'")
-
 	sqlA := s.SQLConn(t, serverutils.DBName("a"))
 
 	var tableName, streamStartStmt string
@@ -2897,8 +2895,14 @@ func TestGetWriterType(t *testing.T) {
 
 	t.Run("validated-mode", func(t *testing.T) {
 		st := cluster.MakeTestingClusterSettings()
+
 		wt, err := getWriterType(ctx, jobspb.LogicalReplicationDetails_Validated, st)
 		require.NoError(t, err)
+		require.Equal(t, sqlclustersettings.LDRWriterTypeCRUD, wt)
+
+		crosscluster.LogicalReplicationUDFWriterEnabled.Override(ctx, &st.SV, true)
+		wt, err = getWriterType(ctx, jobspb.LogicalReplicationDetails_Validated, st)
+		require.NoError(t, err)
 		require.Equal(t, sqlclustersettings.LDRWriterTypeSQL, wt)
 	})
 

pkg/crosscluster/logical/logical_replication_writer_processor.go

@@ -741,11 +741,17 @@ func (lrw *logicalReplicationWriterProcessor) setupBatchHandlers(ctx context.Con
 func getWriterType(
 	ctx context.Context, mode jobspb.LogicalReplicationDetails_ApplyMode, settings *cluster.Settings,
 ) (sqlclustersettings.LDRWriterType, error) {
+	// TODO(jeffswenson): delete the kv and legacy sql ldr writers
 	switch mode {
 	case jobspb.LogicalReplicationDetails_Immediate:
 		return sqlclustersettings.LDRWriterType(sqlclustersettings.LDRImmediateModeWriter.Get(&settings.SV)), nil
 	case jobspb.LogicalReplicationDetails_Validated:
-		return sqlclustersettings.LDRWriterTypeSQL, nil
+		if crosscluster.LogicalReplicationUDFWriterEnabled.Get(&settings.SV) {
+			// If the UDF writer is enabled, fall back to the legacy SQL writer for
+			// validated mode.
+			return sqlclustersettings.LDRWriterTypeSQL, nil
+		}
+		return sqlclustersettings.LDRWriterTypeCRUD, nil
 	default:
 		return "", errors.Newf("unknown logical replication writer type: %s", mode)
 	}

pkg/sql/sqlclustersettings/clustersettings.go

@@ -144,8 +144,7 @@ var LDRImmediateModeWriter = settings.RegisterStringSetting(
 	settings.ApplicationLevel,
 	"logical_replication.consumer.immediate_mode_writer",
 	"the writer to use when in immediate mode",
-	// TODO(jeffswenson): make the crud writer the default
-	metamorphic.ConstantWithTestChoice("logical_replication.consumer.immediate_mode_writer", string(LDRWriterTypeLegacyKV), string(LDRWriterTypeCRUD), string(LDRWriterTypeSQL)),
+	metamorphic.ConstantWithTestChoice("logical_replication.consumer.immediate_mode_writer", string(LDRWriterTypeCRUD), string(LDRWriterTypeLegacyKV), string(LDRWriterTypeSQL)),
 	settings.WithValidateString(func(sv *settings.Values, val string) error {
 		if val != string(LDRWriterTypeSQL) && val != string(LDRWriterTypeLegacyKV) && val != string(LDRWriterTypeCRUD) {
 			return errors.Newf("immediate mode writer must be either 'sql', 'legacy-kv', or 'crud', got '%s'", val)