Merge pull request #1451 from ydb-platform/issue-1395

added test and example for explain query

query/example_test.go

@@ -124,6 +124,33 @@ func Example_queryRow() {
 	fmt.Printf("id=%v, myStr='%s'\n", id, myStr)
 }
 
+func Example_explain() {
+	ctx := context.TODO()
+	db, err := ydb.Open(ctx, "grpc://localhost:2136/local")
+	if err != nil {
+		panic(err)
+	}
+	defer db.Close(ctx) // cleanup resources
+	var (
+		ast  string
+		plan string
+	)
+	err = db.Query().Exec(ctx,
+		`SELECT CAST(42 AS Uint32);`,
+		query.WithExecMode(query.ExecModeExplain),
+		query.WithStatsMode(query.StatsModeNone, func(stats query.Stats) {
+			ast = stats.QueryAST()
+			plan = stats.QueryPlan()
+		}),
+		query.WithIdempotent(),
+	)
+	if err != nil {
+		panic(err)
+	}
+	fmt.Println(plan)
+	fmt.Println(ast)
+}
+
 func Example_withoutRangeIterators() {
 	ctx := context.TODO()
 	db, err := ydb.Open(ctx, "grpc://localhost:2136/local")

tests/integration/query_execute_test.go

@@ -5,6 +5,7 @@ package integration
 
 import (
 	"context"
+	"encoding/json"
 	"fmt"
 	"os"
 	"testing"
@@ -92,6 +93,28 @@ func TestQueryExecute(t *testing.T) {
 			require.True(t, ok)
 		})
 	})
+	t.Run("Explain", func(t *testing.T) {
+		var (
+			ast  string
+			plan map[string]any
+		)
+		err := db.Query().Exec(ctx,
+			`SELECT CAST(42 AS Uint32);`,
+			query.WithExecMode(query.ExecModeExplain),
+			query.WithStatsMode(query.StatsModeNone, func(stats query.Stats) {
+				ast = stats.QueryAST()
+				err := json.Unmarshal([]byte(stats.QueryPlan()), &plan)
+				require.NoError(t, err)
+			}),
+			query.WithIdempotent(),
+		)
+		require.NoError(t, err)
+		for _, key := range []string{"Plan", "tables", "meta"} {
+			_, has := plan[key]
+			require.True(t, has, key)
+		}
+		require.NotEmpty(t, ast)
+	})
 	t.Run("Scan", func(t *testing.T) {
 		var (
 			p1 string