Commit 6345502b authored by ingo@mysql.com's avatar ingo@mysql.com
Browse files

Bug#19604 - CHECK TABLE with concurrent INSERT can reset auto_increment 

CHECK TABLE did temporarily clear the auto_increment value.
It runs with a read lock, allowing other readers and
conurrent INSERTs. The latter could grab the wrong value
in this moment.

CHECK TABLE does no longer modify the auto_increment value.
Not even for a short moment.
parent 91031fc2

myisam/mi_check.c

+16 −18
Original line number Diff line number Diff line
@@ -453,25 +453,24 @@ int chk_key(MI_CHECK *param, register MI_INFO *info) 
    if ((uint) share->base.auto_key -1 == key)

    {

      /* Check that auto_increment key is bigger than max key value */

      ulonglong save_auto_value=info->s->state.auto_increment;

      info->s->state.auto_increment=0;

      ulonglong auto_increment;

      info->lastinx=key;

      _mi_read_key_record(info, 0L, info->rec_buff);

      update_auto_increment(info, info->rec_buff);

      if (info->s->state.auto_increment > save_auto_value)

      auto_increment= retrieve_auto_increment(info, info->rec_buff);

      if (auto_increment > info->s->state.auto_increment)

      {

	mi_check_print_warning(param,

			       "Auto-increment value: %s is smaller than max used value: %s",

			       llstr(save_auto_value,buff2),

			       llstr(info->s->state.auto_increment, buff));

        mi_check_print_warning(param, "Auto-increment value: %s is smaller "

                               "than max used value: %s",

                               llstr(info->s->state.auto_increment,buff2),

                               llstr(auto_increment, buff));

      }

      if (param->testflag & T_AUTO_INC)

      {

        set_if_bigger(info->s->state.auto_increment,

                      auto_increment);

        set_if_bigger(info->s->state.auto_increment,

                      param->auto_increment_value);

      }

      else

	info->s->state.auto_increment=save_auto_value;



      /* Check that there isn't a row with auto_increment = 0 in the table */

      mi_extra(info,HA_EXTRA_KEYREAD,0);
@@ -481,8 +480,8 @@ int chk_key(MI_CHECK *param, register MI_INFO *info) 
      {

	/* Don't count this as a real warning, as myisamchk can't correct it */

	uint save=param->warning_printed;

	mi_check_print_warning(param,

			       "Found row where the auto_increment column has the value 0");

        mi_check_print_warning(param, "Found row where the auto_increment "

                               "column has the value 0");

	param->warning_printed=save;

      }

      mi_extra(info,HA_EXTRA_NO_KEYREAD,0);
@@ -4099,11 +4098,10 @@ void update_auto_increment_key(MI_CHECK *param, MI_INFO *info, 
  }

  else

  {

    ulonglong auto_increment= (repair_only ? info->s->state.auto_increment :

			       param->auto_increment_value);

    info->s->state.auto_increment=0;

    update_auto_increment(info, record);

    ulonglong auto_increment= retrieve_auto_increment(info, record);

    set_if_bigger(info->s->state.auto_increment,auto_increment);

    if (!repair_only)

      set_if_bigger(info->s->state.auto_increment, param->auto_increment_value);

  }

  mi_extra(info,HA_EXTRA_NO_KEYREAD,0);

  my_free((char*) record, MYF(0));

myisam/mi_key.c

+6 −8
Original line number Diff line number Diff line
@@ -509,20 +509,19 @@ int _mi_read_key_record(MI_INFO *info, my_off_t filepos, byte *buf) 




/*

  Update auto_increment info

  Retrieve auto_increment info



  SYNOPSIS

    update_auto_increment()

    retrieve_auto_increment()

    info			MyISAM handler

    record			Row to update



  IMPLEMENTATION

    Only replace the auto_increment value if it is higher than the previous

    one. For signed columns we don't update the auto increment value if it's

    For signed columns we don't retrieve the auto increment value if it's

    less than zero.

*/



void update_auto_increment(MI_INFO *info,const byte *record)

ulonglong retrieve_auto_increment(MI_INFO *info,const byte *record)

{

  ulonglong value= 0;			/* Store unsigned values here */

  longlong s_value= 0;			/* Store signed values here */
@@ -587,6 +586,5 @@ void update_auto_increment(MI_INFO *info,const byte *record) 
    and if s_value == 0 then value will contain either s_value or the

    correct value.

  */

  set_if_bigger(info->s->state.auto_increment,

                (s_value > 0) ? (ulonglong) s_value : value);

  return (s_value > 0) ? (ulonglong) s_value : value;

}

myisam/mi_update.c

+2 −1
Original line number Diff line number Diff line
@@ -164,7 +164,8 @@ int mi_update(register MI_INFO *info, const byte *oldrec, byte *newrec) 
      key_changed|= HA_STATE_CHANGED;		/* Must update index file */

  }

  if (auto_key_changed)

    update_auto_increment(info,newrec);

    set_if_bigger(info->s->state.auto_increment,

                  retrieve_auto_increment(info, newrec));

  if (share->calc_checksum)

    info->state->checksum+=(info->checksum - old_checksum);

myisam/mi_write.c

+2 −1
Original line number Diff line number Diff line
@@ -149,7 +149,8 @@ int mi_write(MI_INFO *info, byte *record) 
    info->state->checksum+=info->checksum;

  }

  if (share->base.auto_key)

    update_auto_increment(info,record);

    set_if_bigger(info->s->state.auto_increment,

                  retrieve_auto_increment(info, record));

  info->update= (HA_STATE_CHANGED | HA_STATE_AKTIV | HA_STATE_WRITTEN |

		 HA_STATE_ROW_CHANGED);

  info->state->records++;

myisam/myisamdef.h

+1 −1
Original line number Diff line number Diff line
@@ -582,7 +582,7 @@ extern uint _mi_pack_key(MI_INFO *info,uint keynr,uchar *key,uchar *old, 
extern int _mi_read_key_record(MI_INFO *info,my_off_t filepos,byte *buf);

extern int _mi_read_cache(IO_CACHE *info,byte *buff,my_off_t pos,

			  uint length,int re_read_if_possibly);

extern void update_auto_increment(MI_INFO *info,const byte *record);

extern ulonglong retrieve_auto_increment(MI_INFO *info,const byte *record);



extern byte *mi_alloc_rec_buff(MI_INFO *,ulong, byte**);

#define mi_get_rec_buff_ptr(info,buf)                              \