Merge pull request #137889 from cockroachdb/blathers/backport-release…

…-24.3-137868

release-24.3: sql: Check for concurrent DSC job in legacy schema changer

pkg/sql/schema_changer.go

@@ -46,6 +46,7 @@ import (
 	"github.com/cockroachdb/cockroach/pkg/sql/pgwire/pgerror"
 	"github.com/cockroachdb/cockroach/pkg/sql/regionliveness"
 	"github.com/cockroachdb/cockroach/pkg/sql/regions"
+	"github.com/cockroachdb/cockroach/pkg/sql/schemachanger/scerrors"
 	"github.com/cockroachdb/cockroach/pkg/sql/sem/catid"
 	"github.com/cockroachdb/cockroach/pkg/sql/sem/eval"
 	"github.com/cockroachdb/cockroach/pkg/sql/sem/tree"
@@ -793,6 +794,13 @@ func (sc *SchemaChanger) exec(ctx context.Context) (retErr error) {
 	if err := sc.checkForMVCCCompliantAddIndexMutations(ctx, desc); err != nil {
 		return err
 	}
+	// Check that the DSC is not active for this descriptor.
+	if catalog.HasConcurrentDeclarativeSchemaChange(desc) {
+		log.Infof(ctx,
+			"aborting legacy schema change job execution because DSC was already active for %q (%d)",
+			desc.GetName(), desc.GetID())
+		return scerrors.ConcurrentSchemaChangeError(desc)
+	}
 
 	log.Infof(ctx,
 		"schema change on %q (v%d) starting execution...",
@@ -3157,7 +3165,8 @@ func (sc *SchemaChanger) applyZoneConfigChangeForMutation(
 func DeleteTableDescAndZoneConfig(
 	ctx context.Context, execCfg *ExecutorConfig, tableDesc catalog.TableDescriptor,
 ) error {
-	log.Infof(ctx, "removing table descriptor and zone config for table %d", tableDesc.GetID())
+	log.Infof(ctx, "removing table descriptor and zone config for table %d (has active dsc=%t)",
+		tableDesc.GetID(), catalog.HasConcurrentDeclarativeSchemaChange(tableDesc))
 	const kvTrace = false
 	return DescsTxn(ctx, execCfg, func(ctx context.Context, txn isql.Txn, col *descs.Collection) error {
 		b := txn.KV().NewBatch()