【OSCP Dev】SCDB 支持 explain statement Feat:support Explain statement for SCDB(#478)

api/scdb_api.proto

@@ -60,7 +60,7 @@ service SCDBService {
   // This interface is suitable for executing fast queries,
   // such as DDL, DCL, and simple DQL. However,
   // if the query takes a long time to run, it may result in a timeout.
-  // Therefore, it is recommended to use the synchronous query API to run
+  // Therefore, it is recommended to use the asynchronous query API to run
   // complex queries.
   rpc SubmitAndGet(SCDBQueryRequest) returns (SCDBQueryResultResponse) {
     option (google.api.http) = {

cmd/regtest/test_util.go

@@ -404,7 +404,7 @@ func (ds *TestDataSource) getQueryResultFromMySQL(query string, needConvertDateT
 		case "INT", "BIGINT", "MEDIUMINT":
 			var a sql.NullInt64
 			curRowColumns[i] = &a
-		case "VARCHAR", "TEXT", "NVARCHAR", "LONGTEXT", "DATETIME", "DURATION", "TIMESTAMP", "DATE":
+		case "VARCHAR", "TEXT", "NVARCHAR", "LONGTEXT", "MEDIUMTEXT", "DATETIME", "DURATION", "TIMESTAMP", "DATE":
 			var a sql.NullString
 			curRowColumns[i] = &a
 		case "BOOL":

docs/api/scdb_api.swagger.yaml

@@ -69,7 +69,7 @@ paths:
         This interface is suitable for executing fast queries,
         such as DDL, DCL, and simple DQL. However,
         if the query takes a long time to run, it may result in a timeout.
-        Therefore, it is recommended to use the synchronous query API to run
+        Therefore, it is recommended to use the asynchronous query API to run
         complex queries.
       operationId: SCDBService_SubmitAndGet
       responses:

pkg/planner/core/planbuilder.go

@@ -842,11 +842,16 @@ func collectVisitInfoFromGrantStmt(sctx sessionctx.Context, vi []visitInfo, stmt
 }
 
 func (b *PlanBuilder) buildExplain(ctx context.Context, explain *ast.ExplainStmt) (Plan, error) {
-	show, ok := explain.Stmt.(*ast.ShowStmt)
-	if !ok {
+	switch stmt := explain.Stmt.(type) {
+	case *ast.ShowStmt:
+		return b.buildShow(ctx, stmt)
+	case *ast.SelectStmt:
+		return b.buildSelect(ctx, stmt)
+	case *ast.UnionStmt:
+		return b.buildUnion(ctx, stmt)
+	default:
 		return nil, ErrUnsupportedType.GenWithStack("Unsupported explain stmt %T", explain.Stmt)
 	}
-	return b.buildShow(ctx, show)
 }
 
 func (b *PlanBuilder) buildInsert(ctx context.Context, insert *ast.InsertStmt) (Plan, error) {

pkg/scdb/server/explain_test.go

@@ -0,0 +1,78 @@
+package server
+
+import (
+	"testing"
+
+	"github.com/stretchr/testify/assert"
+)
+
+func TestIsExplain(t *testing.T) {
+	tests := []struct {
+		name     string
+		query    string
+		expected bool
+		hasError bool
+	}{
+		{
+			name:     "Valid EXPLAIN query",
+			query:    "EXPLAIN SELECT * FROM users",
+			expected: true,
+			hasError: false,
+		},
+		{
+			name:     "Valid EXPLAIN query in lowercase",
+			query:    "explain select * from users",
+			expected: true,
+			hasError: false,
+		},
+		{
+			name:     "Valid EXPLAIN query with whitespace",
+			query:    "  EXPLAIN   SELECT * FROM users  ",
+			expected: true,
+			hasError: false,
+		},
+		{
+			name:     "Non-EXPLAIN query",
+			query:    "SELECT * FROM users",
+			expected: false,
+			hasError: false,
+		},
+		{
+			name:     "INSERT query",
+			query:    "INSERT INTO users (name) VALUES ('alice')",
+			expected: false,
+			hasError: false,
+		},
+		{
+			name:     "Empty query",
+			query:    "",
+			expected: true,
+			hasError: true,
+		},
+		{
+			name:     "EXPLAIN with complex query",
+			query:    "EXPLAIN SELECT u.name, p.title FROM users u JOIN posts p ON u.id = p.user_id WHERE u.age > 18",
+			expected: true,
+			hasError: false,
+		},
+		{
+			name:     "EXPLAIN ANALYZE query",
+			query:    "EXPLAIN ANALYZE SELECT * FROM users",
+			expected: true,
+			hasError: false,
+		},
+	}
+
+	for _, tt := range tests {
+		t.Run(tt.name, func(t *testing.T) {
+			result, err := isExplainQuery(tt.query)
+
+			if tt.hasError {
+				assert.Error(t, err)
+			} else {
+				assert.NoError(t, err)
+				assert.Equal(t, tt.expected, result)
+			}
+		})
+	}
+}

pkg/scdb/server/submit_and_get_handler.go

@@ -371,6 +371,32 @@ func (app *App) runDQL(ctx context.Context, s *session, async bool) (*scql.SCDBQ
 		}
 	}
 
+	isExplain, err := isExplainQuery(s.request.GetQuery())
+	if err != nil {
+		return nil, err
+	}
+
+	if isExplain {
+		explainTensor := &scql.Tensor{
+			Name:     "explain_result",
+			ElemType: scql.PrimitiveDataType_STRING,
+			Option:   scql.TensorOptions_VALUE,
+		}
+
+		explainTensor.StringData = []string{compiledPlan.GetExplain().GetExeGraphDot()}
+
+		return &scql.SCDBQueryResultResponse{
+			Status: &scql.Status{
+				Code:    int32(scql.Code_OK),
+				Message: "ok",
+			},
+			OutColumns:    []*scql.Tensor{explainTensor},
+			ScdbSessionId: s.id,
+			AffectedRows:  0,
+			Warnings:      nil,
+		}, nil
+	}
+
 	engineClient := executor.NewEngineClient(
 		app.config.Engine.ClientMode,
 		app.config.Engine.ClientTimeout,

pkg/scdb/server/submit_handler.go

@@ -139,13 +139,24 @@ func isDQL(sql string) (bool, error) {
 	}
 
 	switch stmt.(type) {
-	case *ast.SelectStmt, *ast.UnionStmt:
+	case *ast.SelectStmt, *ast.UnionStmt, *ast.ExplainStmt:
 		return true, nil
 	}
 
 	return false, nil
 }
 
+func isExplainQuery(sql string) (bool, error) {
+	p := parser.New()
+	stmt, err := p.ParseOneStmt(sql, "", "")
+	if err != nil {
+		return false, err
+	}
+
+	_, ok := stmt.(*ast.ExplainStmt)
+	return ok, nil
+}
+
 // compile and run dql
 func (app *App) submitDQL(ctx context.Context, session *session) *scql.SCDBSubmitResponse {
 	_, err := app.runDQL(ctx, session, true)