vitessio/vitess · error

unexpected diff action

Error message

unexpected diff action

What it means

ErrUnexpectedDiffAction is returned by DDLActionStr when it encounters a sqlparser.DDLAction value it has no string mapping for. This usually means a new DDL action was added to the parser without updating schemadiff's action-to-string table, or an uninitialized/invalid action was passed.

Source

Thrown at go/vt/schemadiff/errors.go:31

See the License for the specific language governing permissions and
limitations under the License.
*/

package schemadiff

import (
	"errors"
	"fmt"
	"strings"

	"vitess.io/vitess/go/sqlescape"
	"vitess.io/vitess/go/vt/sqlparser"
)

var (
	ErrEntityTypeMismatch             = errors.New("mismatched entity type")
	ErrStrictIndexOrderingUnsupported = errors.New("strict index ordering is unsupported")
	ErrUnexpectedDiffAction           = errors.New("unexpected diff action")
	ErrUnexpectedTableSpec            = errors.New("unexpected table spec")
	ErrExpectedCreateTable            = errors.New("expected a CREATE TABLE statement")
	ErrExpectedCreateView             = errors.New("expected a CREATE VIEW statement")
)

type ImpossibleApplyDiffOrderError struct {
	UnorderedDiffs   []EntityDiff
	ConflictingDiffs []EntityDiff
}

func (e *ImpossibleApplyDiffOrderError) Error() string {
	var b strings.Builder
	conflictingStatements := e.ConflictingStatements()
	fmt.Fprintf(&b, "no valid applicable order for diffs. %d diffs found conflicting:", len(conflictingStatements))
	for _, s := range conflictingStatements {
		b.WriteString("\n")
		b.WriteString(s)
	}

View on GitHub (pinned to 01a25a7d17)

Solutions

1. Check that the sqlparser and schemadiff versions match (rebuild the whole module)
2. Add a case for the new DDLAction in DDLActionStr if extending the code
3. Log/inspect the DDLAction value being passed in

switch action {
case sqlparser.AlterDropPrimaryKey, sqlparser.AlterAddColumn /* known actions */ :
	// safe
default:
	// unknown action for DDLActionStr
}

if err != nil {
	if errors.Is(err, schemadiff.ErrUnexpectedDiffAction) {
		log.Warnf("unmapped DDL action %v", action)
	}
}

When it happens

Trigger: Calling schemadiff.DDLActionStr with a DDLAction not covered by its switch; parser version drift where a new action type reaches schemadiff.

Common situations: Upgrading Vitess/sqlparser and custom code exercising new DDL actions; passing a zero-value or otherwise invalid DDLAction.

Related errors

• unexpected table spec
• expected a CREATE TABLE statement
• found no possible unique key on `%s`
• BeforeSchema differs
• AfterSchema differs

AI-assisted analysis of vitessio/vitess@01a25a7d17 (2026-09-01). Data as JSON: /api/errors/0ccea716f91c8dc7. Report an issue: GitHub.