bytebase/bytebase · error

left and right query span result length mismatch: %d != %d

Error message

left and right query span result length mismatch: %d != %d

What it means

Set operations (UNION, INTERSECT, MINUS) require both branches to yield the same number of output columns; mergeOmniSetTableSources throws when the left and right QuerySpanResult lists differ in length. This mirrors Oracle's ORA-01789 class of errors at the lineage-analysis level.

Source

Thrown at backend/plugin/parser/plsql/query_span_extractor_omni.go:364

	}
	right, err := q.extractOmniSelect(stmt.Rarg)
	if err != nil {
		return nil, err
	}
	return mergeOmniSetTableSources(left, right)
}

func mergeOmniSetTableSources(left, right base.TableSource) (base.TableSource, error) {
	if left == nil {
		return right, nil
	}
	if right == nil {
		return left, nil
	}
	leftResults := left.GetQuerySpanResult()
	rightResults := right.GetQuerySpanResult()
	if len(leftResults) != len(rightResults) {
		return nil, errors.Errorf("left and right query span result length mismatch: %d != %d", len(leftResults), len(rightResults))
	}
	result := make([]base.QuerySpanResult, 0, len(leftResults))
	for i, leftResult := range leftResults {
		sourceColumns, _ := base.MergeSourceColumnSet(leftResult.SourceColumns, rightResults[i].SourceColumns)
		result = append(result, base.QuerySpanResult{
			Name:          leftResult.Name,
			SourceColumns: sourceColumns,
			IsPlainField:  false,
		})
	}
	return &base.PseudoTable{Columns: result}, nil
}

func (q *omniQuerySpanExtractor) extractOmniCTE(cte *oracleast.CTE) (*base.PseudoTable, error) {
	if cte == nil {
		return nil, nil
	}
	name := cte.Name

View on GitHub (pinned to 1870550677)

Solutions

1. Fix the SQL so both set-operation branches select the same number of columns
2. Replace SELECT * in union branches with explicit, aligned column lists
3. Re-check the referenced table schemas — a recent column addition may have desynchronized the branches
4. If analysis-side, validate branch arity before merging and emit a user-facing SQL error instead of an internal one

Example fix

// before
SELECT id, name FROM a UNION SELECT id FROM b
// after
SELECT id, name FROM a UNION SELECT id, name FROM b

if len(leftResults) != len(rightResults) { return errors.New("union branches must have equal column counts") }

src, err := extractor.GetQuerySpan(ctx, sql)
if err != nil && strings.Contains(err.Error(), "result length mismatch") {
    return nil, fmt.Errorf("set-operation branches differ in column count: %w", err)
}

When it happens

Trigger: extractOmniSetSelect or extractOmniCTE analyzing a UNION/UNION ALL/INTERSECT/MINUS whose left and right SELECT lists have different column counts — often after * expansion resolves to different widths on each side.

Common situations: Hand-written UNION queries with mismatched SELECT lists; SELECT * on tables whose schemas diverged (column added to one table only); dynamically generated SQL assembling branches independently.

Related errors

• MySQL UNION operator left has %d fields, right has %d fields
• no parse results
• no DML statement found in extracted SQL
• MySQL CTE column list should have the same length, but got %
• failed to prepare transformation

AI-assisted analysis of bytebase/bytebase@1870550677 (2026-09-06). Data as JSON: /api/errors/424940bc6ff2a718. Report an issue: GitHub.