executor,table: fix 'show create table' for the temporary table

executor/show.go

@@ -775,7 +775,13 @@ func ConstructResultOfShowCreateTable(ctx sessionctx.Context, tableInfo *model.T
  }
 
  sqlMode := ctx.GetSessionVars().SQLMode
- fmt.Fprintf(buf, "CREATE TABLE %s (\n", stringutil.Escape(tableInfo.Name.O, sqlMode))
+ tableName := stringutil.Escape(tableInfo.Name.O, sqlMode)
+ switch tableInfo.TempTableType {
+ case model.TempTableGlobal:
+ fmt.Fprintf(buf, "CREATE /* GLOBAL TEMPORARY */ TABLE %s (\n", tableName)
+ default:
+ fmt.Fprintf(buf, "CREATE TABLE %s (\n", tableName)
+ }
  var pkCol *model.ColumnInfo
  var hasAutoIncID bool
  needAddComma := false
@@ -1009,6 +1015,11 @@ func ConstructResultOfShowCreateTable(ctx sessionctx.Context, tableInfo *model.T
  if len(tableInfo.Comment) > 0 {
  fmt.Fprintf(buf, " COMMENT='%s'", format.OutputFormat(tableInfo.Comment))
  }
+
+ if tableInfo.TempTableType == model.TempTableGlobal {
+ fmt.Fprintf(buf, " /* ON COMMIT DELETE ROWS */")
+ }
+
  // add partition info here.
  appendPartitionInfo(tableInfo.Partition, buf)
  return nil

executor/show_test.go

@@ -1303,3 +1303,25 @@ func (s *testSuite5) TestShowPerformanceSchema(c *C) {
  testkit.Rows("events_statements_summary_by_digest 0 SCHEMA_NAME 1 SCHEMA_NAME A 0 <nil> <nil> YES BTREE YES NULL NO",
  "events_statements_summary_by_digest 0 SCHEMA_NAME 2 DIGEST A 0 <nil> <nil> YES BTREE YES NULL NO"))
 }
+
+func (s *testSuite5) TestShowTemporaryTable(c *C) {
+ tk := testkit.NewTestKit(c, s.store)
+ tk.MustExec("use test")
+ tk.MustExec("create global temporary table t1 (id int) on commit delete rows")
+ tk.MustExec("create global temporary table t3 (i int primary key, j int) on commit delete rows")
+ // For issue https://github.com/pingcap/tidb/issues/24752
+ tk.MustQuery("show create table t1").Check(testkit.Rows("t1 CREATE /* GLOBAL TEMPORARY */ TABLE `t1` (\n" +
+ " `id` int(11) DEFAULT NULL\n" +
+ ") ENGINE=InnoDB DEFAULT CHARSET=utf8mb4 COLLATE=utf8mb4_bin /* ON COMMIT DELETE ROWS */"))
+ // No panic, fix issue https://github.com/pingcap/tidb/issues/24788
+ expect := "CREATE /* GLOBAL TEMPORARY */ TABLE `t3` (\n" +
+ " `i` int(11) NOT NULL,\n" +
+ " `j` int(11) DEFAULT NULL,\n" +
+ " PRIMARY KEY (`i`) /*T![clustered_index] CLUSTERED */\n" +
+ ") ENGINE=InnoDB DEFAULT CHARSET=utf8mb4 COLLATE=utf8mb4_bin /* ON COMMIT DELETE ROWS */"
+ tk.MustQuery("show create table t3").Check(testkit.Rows("t3 " + expect))
+
+ // Verify that the `show create table` result can be used to build the table.
+ createTable := strings.ReplaceAll(expect, "t3", "t4")
+ tk.MustExec(createTable)
+}

table/tables/tables.go

@@ -1374,8 +1374,11 @@ func (t *TableCommon) Allocators(ctx sessionctx.Context) autoid.Allocators {
  } else if ctx.GetSessionVars().IDAllocator == nil {
  // Use an independent allocator for global temporary tables.
  if t.meta.TempTableType == model.TempTableGlobal {
- alloc := ctx.GetSessionVars().GetTemporaryTable(t.meta).GetAutoIDAllocator()
- return autoid.Allocators{alloc}
+ if alloc := ctx.GetSessionVars().GetTemporaryTable(t.meta).GetAutoIDAllocator(); alloc != nil {
+ return autoid.Allocators{alloc}
+ }
+ // If the session is not in a txn, for example, in "show create table", use the original allocator.
+ // Otherwise the would be a nil pointer dereference,
  }
  return t.allocs
  }