SQL Expressions: Query Service Support (#101955)

---------

Co-authored-by: Adam Simpson <adam@adamsimpson.net>
Co-authored-by: Sarah Zinger <sarah.zinger@grafana.com>

pkg/registry/apis/query/parser.go

@@ -43,6 +43,9 @@ type parsedRequestInfo struct {
 
 	// Hidden queries used as dependencies
 	HideBeforeReturn []string `json:"hide,omitempty"`
+
+	// SQL Inputs
+	SqlInputs map[string]struct{} `json:"sqlInputs,omitempty"`
 }
 
 type queryParser struct {
@@ -71,6 +74,7 @@ func (p *queryParser) parseRequest(ctx context.Context, input *query.QueryDataRe
 	index := make(map[string]int) // index lookup
 	rsp := parsedRequestInfo{
 		RefIDTypes: make(map[string]string, len(input.Queries)),
+		SqlInputs:  make(map[string]struct{}),
 	}
 
 	for _, q := range input.Queries {
@@ -90,6 +94,7 @@ func (p *queryParser) parseRequest(ctx context.Context, input *query.QueryDataRe
 		}
 
 		// Process each query
+		// check if ds is expression
 		if expr.IsDataSource(ds.UID) {
 			// In order to process the query as a typed expression query, we
 			// are writing it back to JSON and parsing again.  Alternatively we
@@ -149,20 +154,40 @@ func (p *queryParser) parseRequest(ctx context.Context, input *query.QueryDataRe
 		// Build the graph for a request
 		dg := simple.NewDirectedGraph()
 		dg.AddNode(queryNode)
+
 		for _, exp := range expressions {
 			dg.AddNode(exp)
 		}
+
 		for _, exp := range expressions {
 			vars := exp.Command.NeedsVars()
+
 			for _, refId := range vars {
 				target := queryNode
 				q, ok := queryRefIDs[refId]
+
 				if !ok {
-					target, ok = expressions[refId]
-					if !ok {
-						return rsp, makeDependencyError(exp.RefID, refId)
+					_, isSQLCMD := target.Command.(*expr.SQLCommand)
+					if isSQLCMD {
+						continue
+					} else {
+						target, ok = expressions[refId]
+						if !ok {
+							return rsp, makeDependencyError(exp.RefID, refId)
+						}
 					}
 				}
+
+				// If the input is SQL, conversion is handled differently
+				if _, isSqlExp := exp.Command.(*expr.SQLCommand); isSqlExp {
+					if _, ifDepIsAlsoExpression := expressions[refId]; ifDepIsAlsoExpression {
+						// Only allow data source nodes as SQL expression inputs for now
+						return rsp, fmt.Errorf("only data source queries may be inputs to a sql expression, %v is the input for %v", refId, exp.RefID)
+					} else {
+						rsp.SqlInputs[refId] = struct{}{}
+					}
+				}
+
 				// Do not hide queries used in variables
 				if q != nil && q.Hide {
 					q.Hide = false

pkg/registry/apis/query/parser_test.go

@@ -166,6 +166,40 @@ func TestQuerySplitting(t *testing.T) {
 	})
 }
 
+func TestSqlInputs(t *testing.T) {
+	parser := newQueryParser(
+		expr.NewExpressionQueryReader(featuremgmt.WithFeatures(featuremgmt.FlagSqlExpressions)),
+		nil,
+		tracing.InitializeTracerForTest(),
+		log.NewNopLogger(),
+	)
+
+	parsedRequestInfo, err := parser.parseRequest(context.Background(), &query.QueryDataRequest{
+		QueryDataRequest: data.QueryDataRequest{
+			Queries: []data.DataQuery{
+				data.NewDataQuery(map[string]any{
+					"refId": "A",
+					"datasource": &data.DataSourceRef{
+						Type: "prometheus",
+						UID:  "local-prom",
+					},
+				}),
+				data.NewDataQuery(map[string]any{
+					"refId": "B",
+					"datasource": &data.DataSourceRef{
+						Type: "__expr__",
+						UID:  "__expr__",
+					},
+					"type":       "sql",
+					"expression": "Select time, value + 10 from A",
+				}),
+			},
+		},
+	})
+	require.NoError(t, err)
+	require.Equal(t, parsedRequestInfo.SqlInputs["B"], struct{}{})
+}
+
 type legacyDataSourceRetriever struct{}
 
 func (s *legacyDataSourceRetriever) GetDataSourceFromDeprecatedFields(ctx context.Context, name string, id int64) (*data.DataSourceRef, error) {

pkg/registry/apis/query/query.go

@@ -381,11 +381,14 @@ func (b *QueryAPIBuilder) handleExpressions(ctx context.Context, req parsedReque
 			if !ok {
 				dr, ok := qdr.Responses[refId]
 				if ok {
-					_, res, err := b.converter.Convert(ctx, req.RefIDTypes[refId], dr.Frames)
+					_, isSqlInput := req.SqlInputs[refId]
+
+					_, res, err := b.converter.Convert(ctx, req.RefIDTypes[refId], dr.Frames, isSqlInput)
 					if err != nil {
 						expressionsLogger.Error("error converting frames for expressions", "error", err)
 						res.Error = err
 					}
+
 					vars[refId] = res
 				} else {
 					expressionsLogger.Error("missing variable in handle expressions", "refId", refId, "expressionRefId", expression.RefID)
@@ -427,7 +430,7 @@ func (b *QueryAPIBuilder) convertQueryWithoutExpression(ctx context.Context, req
 		return nil, fmt.Errorf("refID '%s' does not exist", refID)
 	}
 	frames := qdr.Responses[refID].Frames
-	_, results, err := b.converter.Convert(ctx, req.PluginId, frames)
+	_, results, err := b.converter.Convert(ctx, req.PluginId, frames, false)
 	if err != nil {
 		results.Error = err
 	}