Commit d3f503a0 authored by ramil/ram@mysql.com/myoffice.izhnet.ru's avatar ramil/ram@mysql.com/myoffice.izhnet.ru
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Fix for bug #20204: "order by" changes the results returned 

Item_substr's results are improperly stored in a temporary table due to       
wrongly calculated max_length value for multi-byte charsets if two            
arguments specified.
parent 43194fad

mysql-test/r/ctype_utf8.result

+13 −0
Original line number Diff line number Diff line
@@ -1352,3 +1352,16 @@ select database(); 
database()

имя_базы_в_кодировке_утф8_длиной_больше_чем_45

drop database имя_базы_в_кодировке_утф8_длиной_больше_чем_45;

use test;

create table t1(a char(10)) default charset utf8;

insert into t1 values ('123'), ('456');

explain

select substr(Z.a,-1), Z.a from t1 as Y join t1 as Z on Y.a=Z.a order by 1;

id	select_type	table	type	possible_keys	key	key_len	ref	rows	Extra

1	SIMPLE	Y	ALL	NULL	NULL	NULL	NULL	2	Using temporary; Using filesort

1	SIMPLE	Z	ALL	NULL	NULL	NULL	NULL	2	Using where

select substr(Z.a,-1), Z.a from t1 as Y join t1 as Z on Y.a=Z.a order by 1;

substr(Z.a,-1)	a

3	123

6	456

drop table t1;

mysql-test/t/ctype_utf8.test

+12 −0
Original line number Diff line number Diff line
@@ -1087,5 +1087,17 @@ create database имя_базы_в_кодировке_утф8_длиной_бо 
use имя_базы_в_кодировке_утф8_длиной_больше_чем_45;

select database();

drop database имя_базы_в_кодировке_утф8_длиной_больше_чем_45;

use test;



#

# Bug #20204: "order by" changes the results returned

#



create table t1(a char(10)) default charset utf8;

insert into t1 values ('123'), ('456');

explain

  select substr(Z.a,-1), Z.a from t1 as Y join t1 as Z on Y.a=Z.a order by 1;

select substr(Z.a,-1), Z.a from t1 as Y join t1 as Z on Y.a=Z.a order by 1;

drop table t1;



# End of 4.1 tests

sql/item_strfunc.cc

+2 −1
Original line number Diff line number Diff line
@@ -1109,12 +1109,13 @@ void Item_func_substr::fix_length_and_dec() 
  }

  if (arg_count == 3 && args[2]->const_item())

  {

    int32 length= (int32) args[2]->val_int() * collation.collation->mbmaxlen;

    int32 length= (int32) args[2]->val_int();

    if (length <= 0)

      max_length=0; /* purecov: inspected */

    else

      set_if_smaller(max_length,(uint) length);

  }

  max_length*= collation.collation->mbmaxlen;

}