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MDEV-25468 DELETE HISTORY may delete current data on system-versioned table

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Item_func_history (is_history()) is a bool function that checks if the
row is the history row by checking row_end->is_max(). The argument to
this function must be row_end system field.

Added the above function to conjunction with SYSTEM_TIME_BEFORE
versioning condition.
This commit is contained in:
Aleksey Midenkov
2021-04-21 22:14:08 +03:00
parent 29b2f3dbb5
commit 6d73282b13
5 changed files with 105 additions and 2 deletions
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33
mysql-test/suite/versioning/r/delete_history.result
View File

@ -129,3 +129,36 @@ select * from t1;
a
1
drop table t1;
#
# MDEV-25468 DELETE HISTORY may delete current data on system-versioned table
#
create or replace table t1 (x int) with system versioning;
insert into t1 values (1);
delete history from t1 before system_time '2039-01-01 23:00';
select * from t1;
x
1
explain extended delete history from t1 before system_time '2039-01-01 23:00';
id select_type table type possible_keys key key_len ref rows filtered Extra
1 SIMPLE t1 ALL NULL NULL NULL NULL 1 100.00 Using where
create or replace procedure p() delete history from t1 before system_time '2039-01-01 23:00';
call p;
select * from t1;
x
1
call p;
select * from t1;
x
1
drop procedure p;
prepare stmt from "delete history from t1 before system_time '2039-01-01 23:00'";
execute stmt;
select * from t1;
x
1
execute stmt;
select * from t1;
x
1
drop prepare stmt;
drop table t1;

22
mysql-test/suite/versioning/t/delete_history.test
View File

@ -141,4 +141,26 @@ insert into t1 values (1);
select * from t1;
drop table t1;
--echo #
--echo # MDEV-25468 DELETE HISTORY may delete current data on system-versioned table
--echo #
create or replace table t1 (x int) with system versioning;
insert into t1 values (1);
delete history from t1 before system_time '2039-01-01 23:00';
select * from t1;
explain extended delete history from t1 before system_time '2039-01-01 23:00';
create or replace procedure p() delete history from t1 before system_time '2039-01-01 23:00';
call p;
select * from t1;
call p;
select * from t1;
drop procedure p;
prepare stmt from "delete history from t1 before system_time '2039-01-01 23:00'";
execute stmt;
select * from t1;
execute stmt;
select * from t1;
drop prepare stmt;
drop table t1;
--source suite/versioning/common_finish.inc

16
sql/item_vers.cc
View File

@ -26,6 +26,22 @@
#include "tztime.h"
#include "item.h"
bool Item_func_history::val_bool()
{
Item_field *f= static_cast<Item_field *>(args[0]);
DBUG_ASSERT(f->fixed);
DBUG_ASSERT(f->field->flags & VERS_SYS_END_FLAG);
return !f->field->is_max();
}
void Item_func_history::print(String *str, enum_query_type query_type)
{
str->append(func_name());
str->append('(');
args[0]->print(str, query_type);
str->append(')');
}
Item_func_trt_ts::Item_func_trt_ts(THD *thd, Item* a, TR_table::field_id_t _trt_field) :
Item_datetimefunc(thd, a),
trt_field(_trt_field)

30
sql/item_vers.h
View File

@ -22,6 +22,36 @@
#pragma interface /* gcc class implementation */
#endif
class Item_func_history: public Item_bool_func
{
public:
/*
@param a Item_field for row_end system field
*/
Item_func_history(THD *thd, Item *a): Item_bool_func(thd, a)
{
DBUG_ASSERT(a->type() == Item::FIELD_ITEM);
}
virtual bool val_bool();
virtual longlong val_int()
{
return (val_bool() ? 1 : 0);
}
bool fix_length_and_dec()
{
maybe_null= 0;
null_value= 0;
decimals= 0;
max_length= 1;
return FALSE;
}
virtual const char* func_name() const { return "is_history"; }
virtual void print(String *str, enum_query_type query_type);
Item *get_copy(THD *thd)
{ return get_item_copy<Item_func_history>(thd, this); }
};
class Item_func_trt_ts: public Item_datetimefunc
{
TR_table::field_id_t trt_field;

6
sql/sql_select.cc
View File

@ -928,7 +928,8 @@ int SELECT_LEX::vers_setup_conds(THD *thd, TABLE_LIST *tables)
cond3= newx Item_func_le(thd, point_in_time1, point_in_time2);
break;
case SYSTEM_TIME_BEFORE:
cond1= newx Item_func_lt(thd, row_end, point_in_time1);
cond1= newx Item_func_history(thd, row_end);
cond2= newx Item_func_lt(thd, row_end, point_in_time1);
break;
default:
DBUG_ASSERT(0);
@ -978,7 +979,8 @@ int SELECT_LEX::vers_setup_conds(THD *thd, TABLE_LIST *tables)
trx_id0= vers_conditions.start.unit == VERS_TIMESTAMP
? newx Item_func_trt_id(thd, point_in_time1, TR_table::FLD_TRX_ID, true)
: point_in_time1;
cond1= newx Item_func_trt_trx_sees(thd, trx_id0, row_end);
cond1= newx Item_func_history(thd, row_end);
cond2= newx Item_func_trt_trx_sees(thd, trx_id0, row_end);
break;
default:
DBUG_ASSERT(0);