feat: support show stmt

Author: dk-lockdown

pkg/executor/sharding.go

@@ -211,7 +211,9 @@ func (executor *ShardingExecutor) ExecutorComQuery(ctx context.Context, sql stri
 	if queryStmt == nil {
 		return nil, 0, errors.New("query stmt should not be nil")
 	}
-	if _, ok := queryStmt.(*ast.SetStmt); ok {
+
+	switch stmt := queryStmt.(type) {
+	case *ast.SetStmt:
 		for _, db := range executor.all {
 			go func(db *DataSourceBrief) {
 				if _, _, err := db.DB.Query(spanCtx, sql); err != nil {
@@ -224,20 +226,28 @@ func (executor *ShardingExecutor) ExecutorComQuery(ctx context.Context, sql stri
 			AffectedRows: 0,
 			InsertId:     0,
 		}, 0, nil
-	}
-	if selectStmt, ok := queryStmt.(*ast.SelectStmt); ok {
-		if selectStmt.Fields != nil && len(selectStmt.Fields.Fields) > 0 {
-			if _, ok := selectStmt.Fields.Fields[0].Expr.(*ast.VariableExpr); ok {
+	case *ast.ShowStmt:
+		return executor.all[0].DB.Query(spanCtx, sql)
+	case *ast.SelectStmt:
+		if stmt.Fields != nil && len(stmt.Fields.Fields) > 0 {
+			if _, ok := stmt.Fields.Fields[0].Expr.(*ast.VariableExpr); ok {
 				return executor.all[0].DB.Query(spanCtx, sql)
 			}
 		}
+		plan, err = executor.optimizer.Optimize(spanCtx, queryStmt)
+		if err != nil {
+			return nil, 0, err
+		}
+		proto.WithVariable(spanCtx, constant.TransactionTimeout, executor.config.TransactionTimeout)
+		return plan.Execute(spanCtx)
+	default:
+		plan, err = executor.optimizer.Optimize(spanCtx, queryStmt)
+		if err != nil {
+			return nil, 0, err
+		}
+		proto.WithVariable(spanCtx, constant.TransactionTimeout, executor.config.TransactionTimeout)
+		return plan.Execute(spanCtx)
 	}
-	plan, err = executor.optimizer.Optimize(spanCtx, queryStmt)
-	if err != nil {
-		return nil, 0, err
-	}
-	proto.WithVariable(spanCtx, constant.TransactionTimeout, executor.config.TransactionTimeout)
-	return plan.Execute(spanCtx)
 }
 
 func (executor *ShardingExecutor) ExecutorComStmtExecute(ctx context.Context, stmt *proto.Stmt) (proto.Result, uint16, error) {

test/shd/sharding_test.go

@@ -181,6 +181,34 @@ func (suite *_ShardingSuite) TestSelectCount() {
 	}
 }
 
+func (suite *_ShardingSuite) TestShowDatabases() {
+	rows, err := suite.db.Query("SHOW DATABASES")
+	if suite.NoErrorf(err, "show databases error: %v", err) {
+		var (
+			database string
+		)
+		for rows.Next() {
+			err := rows.Scan(&database)
+			suite.NoError(err)
+			suite.T().Logf("database: %s", database)
+		}
+	}
+}
+
+func (suite *_ShardingSuite) TestShowEngines() {
+	rows, err := suite.db.Query("SHOW ENGINES")
+	if suite.NoErrorf(err, "show engines error: %v", err) {
+		var (
+			engine, support, comment, transactions, xa, savepoints string
+		)
+		for rows.Next() {
+			err := rows.Scan(&engine, &support, &comment, &transactions, &xa, &savepoints)
+			suite.NoError(err)
+			suite.T().Logf("%s	%s	%s	%s	%s	%s", engine, support, comment, transactions, xa, savepoints)
+		}
+	}
+}
+
 func (suite *_ShardingSuite) TestDeleteDrugResource() {
 	result, err := suite.db.Exec(deleteDrugResource, 10, 20)
 	suite.Assert().Nil(err)