feat: ephemeral measures UI for explore and canvas dashboards

eslint.config.js

@@ -85,6 +85,7 @@ export default [
       "web-common/src/components/modal/*.js",
       "web-common/src/features/dashboards/url-state/filters/expression.js", // generated by nearley
       "web-common/src/features/dashboards/url-state/time-ranges/rill-time.js", // generated by nearley
+      "web-common/src/features/dashboards/ephemeral-measures/measure-expression.js", // generated by nearley
       "web-local/build/*",
       "web-local/playwright-report/*",
       "web-local/playwright/*",

proto/rill/ui/v1/dashboard.proto

@@ -159,6 +159,9 @@ message DashboardState {
 
   // Per-measure conditional formatting (heatmap / data bar) for pivot cells.
   repeated PivotConditionalFormat pivot_conditional_formatting = 44;
+
+  // Ephemeral measures defined for the explore.
+  repeated EphemeralMeasure ephemeral_measures = 45;
 }
 
 message DashboardTimeRange {
@@ -184,6 +187,19 @@ message PivotElement {
   }
 }
 
+// An ephemeral measure defined ad-hoc for an explore dashboard,
+// derived from existing metrics view measures via an arithmetic expression.
+message EphemeralMeasure {
+  // Query alias, e.g. "profit". Must not collide with metrics view field names.
+  string name = 1;
+  // Display name shown in the UI, e.g. "Profit".
+  string display_name = 2;
+  // Arithmetic expression over existing measure names, e.g. "revenue - cost".
+  string expression = 3;
+  // Optional format preset for rendering values.
+  string format_preset = 4;
+}
+
 // Conditional formatting applied to a measure's cells in a pivot table.
 message PivotConditionalFormat {
   string measure = 1;

runtime/canvas/component.go

@@ -592,28 +592,28 @@ func isEncodedTimeDimension(mv *runtimev1.MetricsViewSpec, fieldName string) boo
 	return ok && v != int32(runtimev1.TimeGrain_TIME_GRAIN_UNSPECIFIED)
 }
 
-// ephemeralMeasureNames extracts and validates the optional "ephemeral_measures" renderer property.
+// ephemeralMeasureNames extracts and validates the optional "adhoc_measures" renderer property.
 // Each entry defines an ephemeral measure derived from existing measures via an arithmetic expression;
 // the returned set contains the names that may be referenced alongside the metrics view's own measures.
 func ephemeralMeasureNames(props map[string]any, mvn string, mv *runtimev1.MetricsViewSpec) (map[string]bool, error) {
-	raw, ok := props["ephemeral_measures"]
+	raw, ok := props["adhoc_measures"]
 	if !ok || raw == nil {
 		return nil, nil
 	}
 	list, ok := raw.([]any)
 	if !ok {
-		return nil, errors.New("renderer property 'ephemeral_measures' must be an array")
+		return nil, errors.New("renderer property 'adhoc_measures' must be an array")
 	}
 	names := make(map[string]bool, len(list))
 	for _, item := range list {
 		entry, ok := item.(map[string]any)
 		if !ok {
-			return nil, errors.New("entries in 'ephemeral_measures' must be objects with 'name' and 'expression'")
+			return nil, errors.New("entries in 'adhoc_measures' must be objects with 'name' and 'expression'")
 		}
 		name, _ := entry["name"].(string)
 		expression, _ := entry["expression"].(string)
 		if name == "" || expression == "" {
-			return nil, errors.New("entries in 'ephemeral_measures' must have a non-empty 'name' and 'expression'")
+			return nil, errors.New("entries in 'adhoc_measures' must have a non-empty 'name' and 'expression'")
 		}
 		// Mirror metricsview.AST.checkNameForComputedField, which also rejects the time dimension.
 		// It is often absent from mv.Dimensions, so checking it here surfaces the collision at parse time rather than at query time.

runtime/canvas/component_test.go

@@ -979,7 +979,7 @@ type: component
 kpi_grid:
   metrics_view: mv1
   measures: [y, profit]
-  ephemeral_measures:
+  adhoc_measures:
   - name: profit
     display_name: Profit
     expression: y - z
@@ -995,7 +995,7 @@ leaderboard:
   metrics_view: mv1
   measures: [profit]
   dimensions: [foo]
-  ephemeral_measures:
+  adhoc_measures:
   - name: profit
     display_name: Profit
     expression: y - z
@@ -1010,7 +1010,7 @@ type: component
 table:
   metrics_view: mv1
   columns: [foo, y, profit]
-  ephemeral_measures:
+  adhoc_measures:
   - name: profit
     display_name: Profit
     expression: y - z
@@ -1026,7 +1026,7 @@ pivot:
   metrics_view: mv1
   measures: [profit]
   row_dimensions: [foo]
-  ephemeral_measures:
+  adhoc_measures:
   - name: profit
     display_name: Profit
     expression: y - z
@@ -1047,7 +1047,7 @@ bar_chart:
     field: profit
     type: quantitative
     fields: [y, profit]
-  ephemeral_measures:
+  adhoc_measures:
   - name: profit
     display_name: Profit
     expression: y - z
@@ -1067,7 +1067,7 @@ pie_chart:
   color:
     field: foo
     type: nominal
-  ephemeral_measures:
+  adhoc_measures:
   - name: profit
     display_name: Profit
     expression: y - z
@@ -1087,7 +1087,7 @@ heatmap:
   color:
     field: profit
     type: quantitative
-  ephemeral_measures:
+  adhoc_measures:
   - name: profit
     display_name: Profit
     expression: y - z
@@ -1119,7 +1119,7 @@ type: component
 kpi_grid:
   metrics_view: mv1
   measures: [profit]
-  ephemeral_measures:
+  adhoc_measures:
   - name: profit
     display_name: Profit
     expression: sum(y)
@@ -1135,7 +1135,7 @@ type: component
 kpi_grid:
   metrics_view: mv1
   measures: [profit]
-  ephemeral_measures:
+  adhoc_measures:
   - name: profit
     display_name: Profit
     expression: y - unknown
@@ -1151,7 +1151,7 @@ type: component
 kpi_grid:
   metrics_view: mv1
   measures: [missing]
-  ephemeral_measures:
+  adhoc_measures:
   - name: profit
     display_name: Profit
     expression: y - z

runtime/drivers/clickhouse/dialect.go

@@ -93,6 +93,26 @@ func (d *dialect) CastToDataType(typ runtimev1.Type_Code) (string, error) {
 	}
 }
 
+// OrderByExpression and OrderByAliasExpression place NULLs last regardless of the sort direction,
+// matching the behavior of the DuckDB dialect.
+func (d *dialect) OrderByExpression(name string, desc bool) string {
+	res := d.EscapeIdentifier(name)
+	if desc {
+		res += " DESC"
+	}
+	res += " NULLS LAST"
+	return res
+}
+
+func (d *dialect) OrderByAliasExpression(name string, desc bool) string {
+	res := d.EscapeAlias(name)
+	if desc {
+		res += " DESC"
+	}
+	res += " NULLS LAST"
+	return res
+}
+
 func (d *dialect) JoinOnExpression(lhs, rhs string) string {
 	return fmt.Sprintf("isNotDistinctFrom(%s, %s)", lhs, rhs)
 }

runtime/drivers/dialect.go

@@ -275,8 +275,9 @@ func (b *BaseDialect) CastToDataType(typ runtimev1.Type_Code) (string, error) {
 	}
 }
 
+// SafeDivideExpression returns a division that yields NULL instead of an error, infinity or NaN when the denominator is zero.
 func (b *BaseDialect) SafeDivideExpression(numExpr, denExpr string) string {
-	return fmt.Sprintf("(%s)/CAST(%s AS DOUBLE)", numExpr, denExpr)
+	return fmt.Sprintf("(%s)/NULLIF(CAST(%s AS DOUBLE), 0)", numExpr, denExpr)
 }
 
 func (b *BaseDialect) OrderByExpression(name string, desc bool) string {

runtime/metricsview/ast.go

@@ -493,7 +493,7 @@ func (a *AST) ResolveMeasure(qm Measure, visible bool) (*runtimev1.MetricsViewSp
 	}
 
 	if qm.Compute.ComparisonValue != nil {
-		m, err := a.LookupMeasure(qm.Compute.ComparisonValue.Measure, visible)
+		m, err := a.resolveReferencedMeasure(qm.Compute.ComparisonValue.Measure, visible)
 		if err != nil {
 			return nil, err
 		}
@@ -513,7 +513,7 @@ func (a *AST) ResolveMeasure(qm Measure, visible bool) (*runtimev1.MetricsViewSp
 	}
 
 	if qm.Compute.ComparisonDelta != nil {
-		m, err := a.LookupMeasure(qm.Compute.ComparisonDelta.Measure, visible)
+		m, err := a.resolveReferencedMeasure(qm.Compute.ComparisonDelta.Measure, visible)
 		if err != nil {
 			return nil, err
 		}
@@ -533,7 +533,7 @@ func (a *AST) ResolveMeasure(qm Measure, visible bool) (*runtimev1.MetricsViewSp
 	}
 
 	if qm.Compute.ComparisonRatio != nil {
-		m, err := a.LookupMeasure(qm.Compute.ComparisonRatio.Measure, visible)
+		m, err := a.resolveReferencedMeasure(qm.Compute.ComparisonRatio.Measure, visible)
 		if err != nil {
 			return nil, err
 		}
@@ -559,7 +559,7 @@ func (a *AST) ResolveMeasure(qm Measure, visible bool) (*runtimev1.MetricsViewSp
 			return nil, fmt.Errorf("totals not computed for %s", qm.Name)
 		}
 
-		m, err := a.LookupMeasure(qm.Compute.PercentOfTotal.Measure, visible)
+		m, err := a.resolveReferencedMeasure(qm.Compute.PercentOfTotal.Measure, visible)
 		if err != nil {
 			return nil, err
 		}
@@ -731,6 +731,27 @@ func (a *AST) LookupMeasure(name string, visible bool) (*runtimev1.MetricsViewSp
 	return nil, fmt.Errorf("measure %q not found", name)
 }
 
+// resolveReferencedMeasure resolves a measure referenced by name from another measure,
+// such as the base measure of a comparison delta or a measure referenced by a derived measure.
+// The referenced measure is either a measure in the metrics view or an expression measure defined in the same query,
+// which lets ad-hoc measures support comparisons without being declared in the metrics view.
+// Expression measures may only reference metrics view measures, so the recursion is at most one level deep.
+func (a *AST) resolveReferencedMeasure(name string, visible bool) (*runtimev1.MetricsViewSpec_Measure, error) {
+	for _, m := range a.MetricsView.Measures {
+		if m.Name == name {
+			return a.LookupMeasure(name, visible)
+		}
+	}
+
+	for _, qm := range a.Query.Measures {
+		if qm.Name == name && qm.Compute != nil && qm.Compute.Expression != nil {
+			return a.ResolveMeasure(qm, visible)
+		}
+	}
+
+	return nil, fmt.Errorf("measure %q not found", name)
+}
+
 // GenerateIdentifier generates a unique table identifier for use in the AST.
 func (a *AST) GenerateIdentifier() string {
 	tmp := fmt.Sprintf("t%d", a.nextIdentifier)
@@ -1065,7 +1086,7 @@ func (a *AST) addReferencedMeasuresToScope(n *SelectNode, referencedMeasures []s
 
 	for _, rm := range referencedMeasures {
 		// Note we pass visible==false because the measure won't be projected into the current node's SELECT list, only brought into scope for derived measures.
-		m, err := a.LookupMeasure(rm, false)
+		m, err := a.resolveReferencedMeasure(rm, false)
 		if err != nil {
 			return err
 		}

runtime/metricsview/executor/executor_rewrite_percent_of_totals.go

@@ -14,9 +14,13 @@ func (e *Executor) rewritePercentOfTotals(ctx context.Context, qry *metricsview.
 	var measureIndices []int
 	for i, measure := range qry.Measures {
 		if measure.Compute != nil && measure.Compute.PercentOfTotal != nil {
-			measures = append(measures, metricsview.Measure{
-				Name: measure.Compute.PercentOfTotal.Measure,
-			})
+			// The referenced measure is usually a metrics view measure, but it may also be an expression measure defined in the same query,
+			// in which case the totals query must carry its expression compute.
+			totalOf := metricsview.Measure{Name: measure.Compute.PercentOfTotal.Measure}
+			if qm, ok := queryExpressionMeasure(qry, totalOf.Name); ok {
+				totalOf = qm
+			}
+			measures = append(measures, totalOf)
 			measureIndices = append(measureIndices, i)
 		}
 	}

runtime/metricsview/executor/executor_rewrite_rollup.go

@@ -408,6 +408,12 @@ func rollupEligible(rollup *runtimev1.MetricsViewSpec_Rollup, qry *metricsview.Q
 				return false, rejectComputedMeasure, nil
 			}
 			for _, refName := range refNames {
+				// A comparison compute may reference an expression measure defined in the same query.
+				// That measure is not in the rollup, but the measures it references may be, so check those instead.
+				// Its own rollup safety is checked when the loop reaches it.
+				if _, ok := queryExpressionMeasure(qry, refName); ok {
+					continue
+				}
 				if !rollupMeasures[strings.ToLower(refName)] {
 					return false, rejectMeasureMissing, nil
 				}
@@ -583,6 +589,16 @@ func rollupSafeReferencedMeasures(c *metricsview.MeasureCompute) ([]string, bool
 	return nil, false
 }
 
+// queryExpressionMeasure returns the expression measure with the given name defined in the query, if any.
+func queryExpressionMeasure(qry *metricsview.Query, name string) (metricsview.Measure, bool) {
+	for _, qm := range qry.Measures {
+		if qm.Name == name && qm.Compute != nil && qm.Compute.Expression != nil {
+			return qm, true
+		}
+	}
+	return metricsview.Measure{}, false
+}
+
 // normalizeTimezone validates and normalizes a timezone string for comparison.
 // It normalizes UTC variants (empty, "UTC", "Etc/UTC") to "UTC".
 // Note: Go's time.LoadLocation preserves the input name, so aliases like "US/Eastern"