Commit 8646be88 authored by unknown's avatar unknown
Browse files

Fix for BUG#20524 "auto_increment_* not observed when inserting 

a too large value": the bug was that if MySQL generated a value for an
auto_increment column, based on auto_increment_* variables, and this value
was bigger than the column's max possible value, then that max possible
value was inserted (after issuing a warning). But this didn't honour
auto_increment_* variables (and so could cause conflicts in a master-master
replication where one master is supposed to generated only even numbers,
and the other only odd numbers), so now we "round down" this max possible
value to honour auto_increment_* variables, before inserting it.


mysql-test/r/rpl_auto_increment.result:
  result update. Before the fix, the result was that master inserted 127 in t1
  (which didn't honour auto_increment_* variables!),
  instead of failing with "duplicate key 125" like now.
mysql-test/t/rpl_auto_increment.test:
  Test for BUG#20524 "auto_increment_* not observed when inserting
  a too large value".
  We also check the pathological case (table t2) where it's impossible to
  "round down".
  The fixer of BUG#20573 will be able to use table t2 for testing his fix.
sql/handler.cc:
  If handler::update_auto_increment() generates a value larger than the field's
  max possible value, we used to simply insert this max possible value
  (after pushing a warning). Now we "round down" this max possible value to
  honour auto_increment_* variables (if at all possible), before trying the
  insertion.
parent 0f6a24ad

mysql-test/r/rpl_auto_increment.result

+44 −0
Original line number Diff line number Diff line
@@ -183,3 +183,47 @@ a 
32

42

drop table t1;

create table t1 (a tinyint not null auto_increment primary key) engine=myisam;

insert into t1 values(103);

set auto_increment_increment=11;

set auto_increment_offset=4;

insert into t1 values(null);

insert into t1 values(null);

insert into t1 values(null);

ERROR 23000: Duplicate entry '125' for key 1

select a, mod(a-@@auto_increment_offset,@@auto_increment_increment) from t1 order by a;

a	mod(a-@@auto_increment_offset,@@auto_increment_increment)

103	0

114	0

125	0

create table t2 (a tinyint unsigned not null auto_increment primary key) engine=myisam;

set auto_increment_increment=10;

set auto_increment_offset=1;

set insert_id=1000;

insert into t2 values(null);

Warnings:

Warning	1264	Out of range value adjusted for column 'a' at row 1

select a, mod(a-@@auto_increment_offset,@@auto_increment_increment) from t2 order by a;

a	mod(a-@@auto_increment_offset,@@auto_increment_increment)

251	0

create table t3 like t1;

set auto_increment_increment=1000;

set auto_increment_offset=700;

insert into t3 values(null);

Warnings:

Warning	1264	Out of range value adjusted for column 'a' at row 1

select * from t3 order by a;

a

127

select * from t1 order by a;

a

103

114

125

select * from t2 order by a;

a

251

select * from t3 order by a;

a

127

drop table t1,t2,t3;

mysql-test/t/rpl_auto_increment.test

+39 −1
Original line number Diff line number Diff line
@@ -96,9 +96,47 @@ select * from t1; 


sync_slave_with_master;

select * from t1;

connection master;



# Test for BUG#20524 "auto_increment_* not observed when inserting

# a too large value". When an autogenerated value was bigger than the

# maximum possible value of the field, it was truncated to that max

# possible value, without being "rounded down" to still honour

# auto_increment_* variables.



connection master;

drop table t1;

create table t1 (a tinyint not null auto_increment primary key) engine=myisam;

insert into t1 values(103);

set auto_increment_increment=11;

set auto_increment_offset=4;

insert into t1 values(null);

insert into t1 values(null);

--error 1062

insert into t1 values(null);

select a, mod(a-@@auto_increment_offset,@@auto_increment_increment) from t1 order by a;



# same but with a larger value

create table t2 (a tinyint unsigned not null auto_increment primary key) engine=myisam;

set auto_increment_increment=10;

set auto_increment_offset=1;

set insert_id=1000;

insert into t2 values(null);

select a, mod(a-@@auto_increment_offset,@@auto_increment_increment) from t2 order by a;



# An offset so big that even first value does not fit

create table t3 like t1;

set auto_increment_increment=1000;

set auto_increment_offset=700;

insert into t3 values(null);

select * from t3 order by a;

sync_slave_with_master;

select * from t1 order by a;

select * from t2 order by a;

select * from t3 order by a;



connection master;



drop table t1,t2,t3;



# End cleanup

sync_slave_with_master;

sql/handler.cc

+51 −2
Original line number Diff line number Diff line
@@ -1471,6 +1471,46 @@ next_insert_id(ulonglong nr,struct system_variables *variables) 
}





/*

  Computes the largest number X:

  - smaller than or equal to "nr"

  - of the form: auto_increment_offset + N * auto_increment_increment

  where N>=0.



  SYNOPSIS

    prev_insert_id

      nr            Number to "round down"

      variables     variables struct containing auto_increment_increment and

                    auto_increment_offset



  RETURN

    The number X if it exists, "nr" otherwise.

*/



inline ulonglong

prev_insert_id(ulonglong nr, struct system_variables *variables)

{

  if (unlikely(nr < variables->auto_increment_offset))

  {

    /*

      There's nothing good we can do here. That is a pathological case, where

      the offset is larger than the column's max possible value, i.e. not even

      the first sequence value may be inserted. User will receive warning.

    */

    DBUG_PRINT("info",("auto_increment: nr: %lu cannot honour "

                       "auto_increment_offset: %lu",

                       nr, variables->auto_increment_offset));

    return nr;

  }

  if (variables->auto_increment_increment == 1)

    return nr; // optimization of the formula below

  nr= (((nr - variables->auto_increment_offset)) /

       (ulonglong) variables->auto_increment_increment);

  return (nr * (ulonglong) variables->auto_increment_increment +

          variables->auto_increment_offset);

}





/*

  Update the auto_increment field if necessary
@@ -1580,10 +1620,19 @@ bool handler::update_auto_increment() 
  /* Mark that we should clear next_insert_id before next stmt */

  thd->clear_next_insert_id= 1;



  if (!table->next_number_field->store((longlong) nr, TRUE))

  if (likely(!table->next_number_field->store((longlong) nr, TRUE)))

    thd->insert_id((ulonglong) nr);

  else

    thd->insert_id(table->next_number_field->val_int());

  {

    /*

      overflow of the field; we'll use the max value, however we try to

      decrease it to honour auto_increment_* variables:

    */

    nr= prev_insert_id(table->next_number_field->val_int(), variables);

    thd->insert_id(nr);

    if (unlikely(table->next_number_field->store((longlong) nr, TRUE)))

      thd->insert_id(nr= table->next_number_field->val_int());

  }



  /*

    We can't set next_insert_id if the auto-increment key is not the