schema looks incorrect: %s, expecting at least four lines

Error message

schema looks incorrect: %s, expecting at least four lines

What it means

When generating the CREATE TABLE DDL for the new lookup table, the source table's schema string is split into lines and must have at least three lines (header, at least one column, closing paren). A shorter schema string is malformed, so preparation aborts. The code comments this as effectively unreachable.

Source

Thrown at go/vt/wrangler/materializer.go:671

	}
	onesource := sourceShards[0]
	if onesource.PrimaryAlias == nil {
		return nil, nil, nil, fmt.Errorf("source shard has no primary: %v", onesource.ShardName())
	}
	req := &tabletmanagerdatapb.GetSchemaRequest{Tables: []string{sourceTableName}}
	tableSchema, err := schematools.GetSchema(ctx, wr.ts, wr.tmc, onesource.PrimaryAlias, req)
	if err != nil {
		return nil, nil, nil, err
	}
	if len(tableSchema.TableDefinitions) != 1 {
		return nil, nil, nil, fmt.Errorf("unexpected number of tables returned from schema: %v", tableSchema.TableDefinitions)
	}

	// Generate "create table" statement
	lines := strings.Split(tableSchema.TableDefinitions[0].Schema, "\n")
	if len(lines) < 3 {
		// Unreachable
		return nil, nil, nil, fmt.Errorf("schema looks incorrect: %s, expecting at least four lines", tableSchema.TableDefinitions[0].Schema)
	}
	var modified []string
	modified = append(modified, strings.Replace(lines[0], sourceTableName, targetTableName, 1))
	for i := range sourceVindexColumns {
		line, err := generateColDef(lines, sourceVindexColumns[i], vindexFromCols[i])
		if err != nil {
			return nil, nil, nil, err
		}
		modified = append(modified, line)
	}

	if vindex.Params["data_type"] == "" || strings.EqualFold(vindex.Type, "consistent_lookup_unique") || strings.EqualFold(vindex.Type, "consistent_lookup") {
		modified = append(modified, fmt.Sprintf("  %s varbinary(128),", sqlescape.EscapeID(vindexToCol)))
	} else {
		modified = append(modified, fmt.Sprintf("  %s %s,", sqlescape.EscapeID(vindexToCol), sqlescape.EscapeID(vindex.Params["data_type"])))
	}
	buf := sqlparser.NewTrackedBuffer(nil)
	fmt.Fprintf(buf, "  PRIMARY KEY (")

View on GitHub (pinned to 01a25a7d17)

Solutions

Re-fetch/reload the schema on the source primary (`vtctldclient ReloadSchema`) and retry
Inspect the actual CREATE TABLE on the source primary and recreate the table with a standard multi-line DDL if it is malformed
Report to Vitess maintainers if a normal table triggers this — it indicates a schema-serialization problem

Example fix

null

Defensive patterns

Strategy: try-catch

Validate before calling

null

Type guard

func schemaLooksSane(createTableSQL string) bool {
    return len(strings.Split(createTableSQL, "\n")) >= 3
}

Try / catch

if err := createLookupVindex(...); err != nil {
    if strings.Contains(err.Error(), "schema looks incorrect") {
        _ = reloadTabletSchema(ctx, primaryAlias) // retry once after reload
        return createLookupVindex(...)
    }
    return err
}

Prevention

Inspect SHOW CREATE TABLE output if it ever appears single-line or truncated
Reload schema on tablets after unusual restore/clone operations
Report occurrences upstream — this path is expected to be unreachable

When it happens

Trigger: The CREATE TABLE statement stored in TableDefinitions[0].Schema contains fewer than 3 newline-separated lines — e.g. a single-line or truncated schema string returned by the tablet.

Common situations: Corrupted or nonstandard schema dump; a table definition fetched from an unusual MySQL flavor or proxy that reformats DDL onto one line.

Related errors

AI-assisted analysis of vitessio/vitess@01a25a7d17 (2026-09-01). Data as JSON: /api/errors/b52f9d6e766717df. Report an issue: GitHub.