Commit ece17ba3 authored by unknown's avatar unknown
Browse files

- a fix for Bug#11458 "Prepared statement with subselects return random 

data": remove the fix for another bug (8807) that
added OUTER_REF_TABLE_BIT to all subqueries that used a placeholder
to prevent their evaluation at prepare. As this bit hanged in 
Item_subselect::used_tables_cache for ever, a constant subquery with
a placeholder was never evaluated as such, which caused wrong 
choice of the execution plan for the statement.
- to fix Bug#8807 backport a better fix from 5.0
- post-review fixes.


mysql-test/r/ps.result:
  Bug#11458: test results fixed
mysql-test/t/ps.test:
  - add a test case for Bug#11458 "Prepared statement with subselects return 
  random data"
sql/item.cc:
  - remove unnecessary Item_param::fix_fields
  - fix Item_param::set_null to set item_type accordingly (safety:
    Item_param should behave like a basic constant).
sql/item.h:
  Remove Item_param::fix_fields
sql/item_subselect.h:
  Remove no more existing friend.
sql/mysql_priv.h:
  Add UNCACHEABLE_PREPARE to mark all subqueries as uncacheable if
  in statement prepare (backport from 5.0).
sql/sql_lex.h:
  Comment fixed.
sql/sql_parse.cc:
  If in statement prepare, mark all subqueries as uncacheable (backport
  from 5.0)
sql/sql_prepare.cc:
  Switch off the uncacheable flag from all subqueries after statement
  prepare is done (backport from 5.0)
parent bc0eef3e

mysql-test/r/ps.result

+57 −0
Original line number Diff line number Diff line
@@ -563,3 +563,60 @@ execute stmt; 
execute stmt;

deallocate prepare stmt;

drop table t1;

create table t1 (

id int(11) unsigned not null primary key auto_increment,

partner_id varchar(35) not null,

t1_status_id int(10) unsigned

);

insert into t1 values ("1", "partner1", "10"), ("2", "partner2", "10"),

("3", "partner3", "10"), ("4", "partner4", "10");

create table t2 (

id int(11) unsigned not null default '0',

t1_line_id int(11) unsigned not null default '0',

article_id varchar(20),

sequence int(11) not null default '0',

primary key  (id,t1_line_id)

);

insert into t2 values ("1", "1", "sup", "0"), ("2", "1", "sup", "1"),

("2", "2", "sup", "2"), ("2", "3", "sup", "3"),

("2", "4", "imp", "4"), ("3", "1", "sup", "0"),

("4", "1", "sup", "0");

create table t3 (

id int(11) not null default '0',

preceeding_id int(11) not null default '0',

primary key  (id,preceeding_id)

);

create table t4 (

user_id varchar(50) not null,

article_id varchar(20) not null,

primary key  (user_id,article_id)

);

insert into t4 values("nicke", "imp");

prepare stmt from

'select distinct t1.partner_id

from t1 left join t3 on t1.id = t3.id

     left join t1 pp on pp.id = t3.preceeding_id

where

  exists (

    select *

    from t2 as pl_inner

    where pl_inner.id = t1.id

    and pl_inner.sequence <= (

      select min(sequence) from t2 pl_seqnr

      where pl_seqnr.id = t1.id

    )

    and exists (

      select * from t4

      where t4.article_id = pl_inner.article_id

      and t4.user_id = ?

    )

  )

  and t1.id = ?

group by t1.id

having count(pp.id) = 0';

set @user_id = 'nicke';

set @id = '2';

execute stmt using @user_id, @id;

partner_id

execute stmt using @user_id, @id;

partner_id

mysql-test/t/ps.test

+68 −0
Original line number Diff line number Diff line
@@ -581,3 +581,71 @@ execute stmt; 
execute stmt;

deallocate prepare stmt;

drop table t1;



#

# Bug#11458 "Prepared statement with subselects return random data":

# drop PARAM_TABLE_BIT from the list of tables used by a subquery

#

create table t1 (

  id int(11) unsigned not null primary key auto_increment,

  partner_id varchar(35) not null,

  t1_status_id int(10) unsigned

);



insert into t1 values ("1", "partner1", "10"), ("2", "partner2", "10"),

                      ("3", "partner3", "10"), ("4", "partner4", "10");



create table t2 (

  id int(11) unsigned not null default '0',

  t1_line_id int(11) unsigned not null default '0',

  article_id varchar(20),

  sequence int(11) not null default '0',

  primary key  (id,t1_line_id)

);



insert into t2 values ("1", "1", "sup", "0"), ("2", "1", "sup", "1"),

                      ("2", "2", "sup", "2"), ("2", "3", "sup", "3"),

                      ("2", "4", "imp", "4"), ("3", "1", "sup", "0"),

                      ("4", "1", "sup", "0");



create table t3 (

  id int(11) not null default '0',

  preceeding_id int(11) not null default '0',

  primary key  (id,preceeding_id)

);



create table t4 (

  user_id varchar(50) not null,

  article_id varchar(20) not null,

  primary key  (user_id,article_id)

);



insert into t4 values("nicke", "imp");



prepare stmt from

'select distinct t1.partner_id

from t1 left join t3 on t1.id = t3.id

     left join t1 pp on pp.id = t3.preceeding_id

where

  exists (

    select *

    from t2 as pl_inner

    where pl_inner.id = t1.id

    and pl_inner.sequence <= (

      select min(sequence) from t2 pl_seqnr

      where pl_seqnr.id = t1.id

    )

    and exists (

      select * from t4

      where t4.article_id = pl_inner.article_id

      and t4.user_id = ?

    )

  )

  and t1.id = ?

group by t1.id

having count(pp.id) = 0';

set @user_id = 'nicke';

set @id = '2';

execute stmt using @user_id, @id;

execute stmt using @user_id, @id;

sql/item.cc

+1 −28
Original line number Diff line number Diff line
@@ -889,6 +889,7 @@ void Item_param::set_null() 
  max_length= 0;

  decimals= 0;

  state= NULL_VALUE;

  item_type= Item::NULL_ITEM;

  DBUG_VOID_RETURN;

}
@@ -1339,34 +1340,6 @@ bool Item_param::convert_str_value(THD *thd) 
  return rc;

}



bool Item_param::fix_fields(THD *thd, TABLE_LIST *tables, Item **ref)

{

  DBUG_ASSERT(fixed == 0);

  SELECT_LEX *cursel= (SELECT_LEX *) thd->lex->current_select;



  /*

    Parameters in a subselect should mark the subselect as not constant

    during prepare

  */

  if (state == NO_VALUE)

  {

    /*

      SELECT_LEX_UNIT::item set only for subqueries, so test of it presence

      can be barrier to stop before derived table SELECT or very outer SELECT

    */

    for(;

        cursel->master_unit()->item;

        cursel= cursel->outer_select())

    {

      Item_subselect *subselect_item= cursel->master_unit()->item;

      subselect_item->used_tables_cache|= OUTER_REF_TABLE_BIT;

      subselect_item->const_item_cache= 0;

    }

  }

  fixed= 1;

  return 0;

}





bool Item_param::basic_const_item() const

{

sql/item.h

+0 −1
Original line number Diff line number Diff line
@@ -564,7 +564,6 @@ class Item_param :public Item 
  bool get_time(TIME *tm);

  bool get_date(TIME *tm, uint fuzzydate);

  int  save_in_field(Field *field, bool no_conversions);

  bool fix_fields(THD *, struct st_table_list *, Item **);



  void set_null();

  void set_int(longlong i, uint32 max_length_arg);

sql/item_subselect.h

+0 −1
Original line number Diff line number Diff line
@@ -119,7 +119,6 @@ class Item_subselect :public Item_result_field 
  friend class Item_in_optimizer;

  friend bool Item_field::fix_fields(THD *, TABLE_LIST *, Item **);

  friend bool Item_ref::fix_fields(THD *, TABLE_LIST *, Item **);

  friend bool Item_param::fix_fields(THD *, TABLE_LIST *, Item **);

};



/* single value subselect */