add session system var delete_opt_to_truncate

pkg/frontend/variables.go

@@ -1726,6 +1726,14 @@ var gSysVarsDefs = map[string]SystemVariable{
 		Type:              InitSystemVariableIntType("delayed_queue_size", 1, math.MaxInt64, false),
 		Default:           int64(1000),
 	},
+	"delete_opt_to_truncate": {
+		Name:              "delete_opt_to_truncate",
+		Scope:             ScopeSession,
+		Dynamic:           true,
+		SetVarHintApplies: false,
+		Type:              InitSystemVariableBoolType("delete_opt_to_truncate"),
+		Default:           int64(1),
+	},
 	"disabled_storage_engines": {
 		Name:              "disabled_storage_engines",
 		Scope:             ScopeGlobal,

pkg/sql/plan/build_dml_util.go

@@ -265,6 +265,25 @@ func getStepByNodeId(builder *QueryBuilder, nodeId int32) int {
 	return -1
 }
 
+func checkDeleteOptToTruncate(ctx CompilerContext) (bool, error) {
+	value, err := ctx.ResolveVariable("delete_opt_to_truncate", true, false)
+	if err != nil {
+		return false, err
+	}
+
+	if value == nil {
+		return true, nil
+	}
+
+	if v, ok := value.(int64); ok {
+		return v == 1, nil
+	} else if v1, ok := value.(int8); ok {
+		return v1 == 1, nil
+	} else {
+		return false, moerr.NewInternalErrorf(ctx.GetContext(), "invalid  %v ", value)
+	}
+}
+
 // buildDeletePlans  build preinsert plan.
 /*
 [o1]sink_scan -> join[u1] -> sink
@@ -334,10 +353,15 @@ func buildDeletePlans(ctx CompilerContext, builder *QueryBuilder, bindCtx *BindC
 		return err
 	}
 
+	deleteOptToTruncate, err := checkDeleteOptToTruncate(ctx)
+	if err != nil {
+		return err
+	}
+
 	if enabled && len(delCtx.tableDef.RefChildTbls) > 0 ||
 		delCtx.tableDef.ViewSql != nil ||
 		(util.TableIsClusterTable(delCtx.tableDef.GetTableType()) && accountId != catalog.System_Account) ||
-		delCtx.objRef.PubInfo != nil {
+		delCtx.objRef.PubInfo != nil || !deleteOptToTruncate {
 		canTruncate = false
 	}
 

pkg/sql/plan/mock.go

@@ -96,6 +96,7 @@ func (m *MockCompilerContext) ResolveVariable(varName string, isSystemVar, isGlo
 	dec, _ := types.ParseDecimal128("200.001", 38, 3)
 	vars["decimal_var"] = dec
 	vars["null_var"] = nil
+	vars["delete_opt_to_truncate"] = int64(1)
 
 	if m.mysqlCompatible {
 		vars["sql_mode"] = ""

test/distributed/cases/prepare/prepare.result

@@ -605,3 +605,40 @@ prepare stmt1x from 'select count(*) from system.statement_info limit 0';
 execute stmt1x;
 count(*)
 drop account prepare_acc01;
+create database prepare_test_2;
+use prepare_test_2;
+drop table if exists tb_delete_opt_to_truncate;
+create table tb_delete_opt_to_truncate(col1 int, col2 int);
+insert into tb_delete_opt_to_truncate values(1, 2), (2,3);
+prepare st_delete_opt_to_truncate from select * from tb_delete_opt_to_truncate order by col1;
+execute st_delete_opt_to_truncate;
+col1    col2
+1    2
+2    3
+delete from tb_delete_opt_to_truncate;
+execute st_delete_opt_to_truncate;
+internal error: table 'tb_delete_opt_to_truncate' has been changed, please reset prepare statement 'st_delete_opt_to_truncate'
+set session delete_opt_to_truncate = 0;
+insert into tb_delete_opt_to_truncate values(1, 2), (2,3);
+prepare st_delete_opt_to_truncate from select * from tb_delete_opt_to_truncate order by col1;
+execute st_delete_opt_to_truncate;
+col1    col2
+1    2
+2    3
+delete from tb_delete_opt_to_truncate;
+execute st_delete_opt_to_truncate;
+col1    col2
+set session delete_opt_to_truncate = 1;
+insert into tb_delete_opt_to_truncate values(1, 2), (2,3);
+prepare st_delete_opt_to_truncate from select * from tb_delete_opt_to_truncate order by col1;
+execute st_delete_opt_to_truncate;
+col1    col2
+1    2
+2    3
+delete from tb_delete_opt_to_truncate;
+execute st_delete_opt_to_truncate;
+internal error: table 'tb_delete_opt_to_truncate' has been changed, please reset prepare statement 'st_delete_opt_to_truncate'
+set session delete_opt_to_truncate = 123;
+internal error: convert to the system variable bool type failed
+drop table tb_delete_opt_to_truncate;
+drop database prepare_test_2;

test/distributed/cases/prepare/prepare.test

@@ -466,3 +466,35 @@ execute stmt1x;
 -- @session
 
 drop account prepare_acc01;
+
+create database prepare_test_2;
+use prepare_test_2;
+drop table if exists tb_delete_opt_to_truncate;
+create table tb_delete_opt_to_truncate(col1 int, col2 int);
+insert into tb_delete_opt_to_truncate values(1, 2), (2,3);
+prepare st_delete_opt_to_truncate from select * from tb_delete_opt_to_truncate order by col1;
+execute st_delete_opt_to_truncate;
+delete from tb_delete_opt_to_truncate;
+execute st_delete_opt_to_truncate;
+
+set session delete_opt_to_truncate = 0;
+insert into tb_delete_opt_to_truncate values(1, 2), (2,3);
+prepare st_delete_opt_to_truncate from select * from tb_delete_opt_to_truncate order by col1;
+execute st_delete_opt_to_truncate;
+delete from tb_delete_opt_to_truncate;
+execute st_delete_opt_to_truncate;
+
+set session delete_opt_to_truncate = 1;
+insert into tb_delete_opt_to_truncate values(1, 2), (2,3);
+prepare st_delete_opt_to_truncate from select * from tb_delete_opt_to_truncate order by col1;
+execute st_delete_opt_to_truncate;
+delete from tb_delete_opt_to_truncate;
+execute st_delete_opt_to_truncate;
+
+set session delete_opt_to_truncate = 123;
+
+drop table tb_delete_opt_to_truncate;
+drop database prepare_test_2;
+
+
+