SigNoz/signoz · error

error while fetching logs schema: %s

Error message

error while fetching logs schema: %s

What it means

Error running SHOW CREATE TABLE against the logs local table while building the attribute-key response; the response uses the DDL to decide whether a tag is a real column (isColumn). Failing here aborts the whole attribute-keys result even though the key rows were fetched.

Source

Thrown at pkg/query-service/app/clickhouseReader/reader.go:3504

		v3.AggregateOperatorNoOp:
		return &v3.AggregateAttributeResponse{}, nil
	default:
		return nil, fmt.Errorf("unsupported aggregate operator")
	}

	query = fmt.Sprintf("SELECT DISTINCT(tag_key), tag_type, tag_data_type from %s.%s WHERE %s and tag_type != 'logfield' limit $2", r.logsDB, r.logsTagAttributeTableV2, where)
	rows, err = r.db.Query(ctx, query, fmt.Sprintf("%%%s%%", req.SearchText), req.Limit)
	if err != nil {
		r.logger.Error("Error while executing query", errorsV2.Attr(err))
		return nil, fmt.Errorf("error while executing query: %s", err.Error())
	}
	defer rows.Close()

	statements := []model.ShowCreateTableStatement{}
	query = fmt.Sprintf("SHOW CREATE TABLE %s.%s", r.logsDB, r.logsLocalTableName)
	err = r.db.Select(ctx, &statements, query)
	if err != nil {
		return nil, fmt.Errorf("error while fetching logs schema: %s", err.Error())
	}

	var tagKey string
	var dataType string
	var attType string
	for rows.Next() {
		if err := rows.Scan(&tagKey, &attType, &dataType); err != nil {
			return nil, fmt.Errorf("error while scanning rows: %s", err.Error())
		}
		key := v3.AttributeKey{
			Key:      tagKey,
			DataType: v3.AttributeKeyDataType(dataType),
			Type:     v3.AttributeKeyType(attType),
			IsColumn: isColumn(statements[0].Statement, attType, tagKey, dataType),
		}
		response.AttributeKeys = append(response.AttributeKeys, key)
	}
	// add other attributes

View on GitHub (pinned to 5069bf80b0)

Solutions

1. Verify the table exists: SHOW CREATE TABLE <logsDB>.<logsLocalTableName>
2. Fix logsDB/logsLocalTableName in query-service config
3. Grant the ClickHouse user sufficient read privileges
4. Align query-service version with deployed schema

// Precheck DDL access
if _, err := db.Exec(ctx, fmt.Sprintf("SHOW CREATE TABLE %s.%s", logsDB, localTable)); err != nil {
    return fmt.Errorf("logs table inaccessible: %w", err)
}

if err != nil {
    // fall back to returning keys without isColumn info
    return keysWithUnknownColumnFlag(rows)
}

When it happens

Trigger: logsLocalTableName or logsDB pointing at a non-existent table; ClickHouse user lacking SHOW/SELECT privilege on system tables; table renamed during upgrade.

Common situations: Config drift after renaming logs database/tables; version mismatch where query-service expects distributed_logs but deployment has different name; restricted ClickHouse user permissions.

Related errors

• removing a selected field is not allowed, please reach out t
• error while fetching trace schema: %s
• CodeLicenseUnavailable
• CodeForbidden
• CodeNotFound

AI-assisted analysis of SigNoz/signoz@5069bf80b0 (2026-08-28). Data as JSON: /api/errors/5bef8eedf49fd957. Report an issue: GitHub.