SigNoz/signoz · error · model.ApiError

cannot join the given group keys

Error message

cannot join the given group keys

What it means

For formula (expression) queries, the group-by keys of all referenced queries must be joinable — expression.CanJoin checks compatibility. If group keys don't align (e.g. different groupBy sets that can't be merged), the query is rejected.

Source

Thrown at pkg/query-service/app/parser.go:827

							groupKeys[v] = append(groupKeys[v], key.Key)
						}
					} else {
						return nil, &model.ApiError{Typ: model.ErrorBadData, Err: fmt.Errorf("unknown variable %s", v)}
					}
				}

				params := make(map[string]interface{})
				for k, v := range groupKeys {
					params[k] = v
				}

				can, _, err := expression.CanJoin(params)
				if err != nil {
					return nil, &model.ApiError{Typ: model.ErrorBadData, Err: err}
				}

				if !can {
					return nil, &model.ApiError{Typ: model.ErrorBadData, Err: fmt.Errorf("cannot join the given group keys")}
				}
			}

			// If the step interval is less than the minimum allowed step interval, set it to the minimum allowed step interval
			if minStep := common.MinAllowedStepInterval(queryRangeParams.Start, queryRangeParams.End); query.StepInterval < minStep {
				query.StepInterval = minStep
			}

			if query.DataSource == v3.DataSourceMetrics {
				// if the time range is greater than 1 day, and less than 1 week set the step interval to be multiple of 5 minutes
				// if the time range is greater than 1 week, set the step interval to be multiple of 30 mins
				start, end := queryRangeParams.Start, queryRangeParams.End
				if end-start >= 24*time.Hour.Milliseconds() && end-start < 7*24*time.Hour.Milliseconds() {
					query.StepInterval = int64(math.Round(float64(query.StepInterval)/300)) * 300
				} else if end-start >= 7*24*time.Hour.Milliseconds() {
					query.StepInterval = int64(math.Round(float64(query.StepInterval)/1800)) * 1800
				}
			}

View on GitHub (pinned to 5069bf80b0)

Solutions

1. Align group-by dimensions across all queries used in the expression (use the same groupBy set)
2. Group at a common coarser dimension present in both queries
3. Remove the formula or split it into separate panels if the join is semantically invalid

Example fix

// before
A: groupBy [service_name]; B: groupBy [operation_name]; expr: A + B
// after
A: groupBy [service_name]; B: groupBy [service_name]; expr: A + B

keys := map[string][]string{}
for _, v := range vars { keys[v] = groupKeysOf(v) }
if can, _, err := expression.CanJoin(toParams(keys)); err != nil || !can { return errors.New("group-bys are not joinable; align dimensions") }

When it happens

Trigger: Formula 'A + B' where A groups by service_name and B groups by operation_name (disjoint group-bys), producing a non-joinable combination.

Common situations: Building a formula over queries with mismatched group-by dimensions in the dashboard UI; modifying groupBy of one query after creating the formula.

Related errors

• CodeLicenseUnavailable
• CodeInvalidInput
• CodeForbidden
• CodeNotFound
• ErrCodeInvalidState

AI-assisted analysis of SigNoz/signoz@5069bf80b0 (2026-08-28). Data as JSON: /api/errors/e1c45eeb6a816a9c. Report an issue: GitHub.