[flash-1018]fix bug of datetime default value (#534) (#536)

* fix bug of datetime default value

Co-authored-by: Fei Han <[email protected]>

dbms/src/Storages/Transaction/SchemaBuilder.cpp

@@ -36,7 +36,12 @@ inline void setAlterCommandColumn(Logger * log, AlterCommand & command, const Co
     if (!column_info.origin_default_value.isEmpty())
     {
         LOG_DEBUG(log, "add default value for column: " << column_info.name);
-        auto arg0 = std::make_shared<ASTLiteral>(column_info.defaultValueToField());
+        ASTPtr arg0;
+        // If it's date time types, we should use string literal to generate default value.
+        if (column_info.tp == TypeDatetime || column_info.tp == TypeTimestamp || column_info.tp == TypeDate)
+            arg0 = std::make_shared<ASTLiteral>(Field(column_info.origin_default_value.convert<String>()));
+        else
+            arg0 = std::make_shared<ASTLiteral>(column_info.defaultValueToField());
         auto arg1 = std::make_shared<ASTLiteral>(command.data_type->getName());
         auto args = std::make_shared<ASTExpressionList>();
         args->children.emplace_back(arg0);

tests/fullstack-test/ddl/datetime_default_value.test

@@ -0,0 +1,36 @@
+mysql> drop table if exists test.t
+mysql> create table test.t(a int)
+mysql> alter table test.t set tiflash replica 1
+mysql> insert into test.t (a) values (1);
+mysql> insert into test.t (a) values (1);
+
+SLEEP 15
+
+
+>> DBGInvoke __try_flush()
+
+mysql> set session tidb_isolation_read_engines='tiflash'; select /*+ read_from_storage(tiflash[t]) */ * from test.t;
++------+
+| a    |
++------+
+|    1 |
+|    1 |
++------+
+
+mysql> alter table test.t add column b datetime default '8124-05-31 23:47:33';
+mysql> set session tidb_isolation_read_engines='tiflash'; select /*+ read_from_storage(t) */ * from test.t;
++------+---------------------+
+| a    | b                   |
++------+---------------------+
+|    1 | 8124-05-31 23:47:33 |
+|    1 | 8124-05-31 23:47:33 |
++------+---------------------+
+
+mysql> alter table test.t add column c datetime default 19910905;
+mysql> set session tidb_isolation_read_engines='tiflash'; select /*+ read_from_storage(t) */ * from test.t;
++------+---------------------+---------------------+
+| a    | b                   | c                   |
++------+---------------------+---------------------+
+|    1 | 8124-05-31 23:47:33 | 1991-09-05 00:00:00 |
+|    1 | 8124-05-31 23:47:33 | 1991-09-05 00:00:00 |
++------+---------------------+---------------------+