Hi, Sergei! Thanks for you review.
04.02.2019, 21:59, "Sergei Golubchik" <s...@mariadb.org>: > Hi, Eugene! > > On Feb 04, Eugene Kosov wrote: >> revision-id: f93af1f93e2 (mariadb-10.3.12-19-gf93af1f93e2) >> parent(s): d4144c8e010 >> author: Eugene Kosov <clap...@yandex.ru> >> committer: Eugene Kosov <clap...@yandex.ru> >> timestamp: 2019-01-23 19:32:02 +0300 >> message: >> >> MDEV-12836 Avoid table rebuild when adding or removing of auto_increment >> settings >> >> ALTER_AUTO_INC: this flag indicates that ALTER operation >> adds or removes AUTO_INCREMENT from some field >> >> Field::is_equal(): now sometime returns IS_EQUAL_BUT_AUTO_INC >> which means that only AUTO_INCREMENT was changed for that field > > You enable instant alter for adding auto_inc. This is not what > Valerii asked for in MDEV-12836, and for a reason. Consider this test > case: > > create table t1 (a int unique); > insert t1 values (NULL),(NULL),(NULL); > alter table t1 modify a int auto_increment; Here we ha_alter_info->handler_flags are: ALTER_CHANGE_COLUMN_DEFAULT ALTER_DROP_UNIQUE_INDEX ALTER_ADD_PK_INDEX ALTER_COLUMN_NOT_NULLABLE This is in a tt-10.3-MDEV-12836-instant-auto-inc branch. F.ex ALTER_COLUMN_NOT_NULLABLE requires rebuild in InnoDB not counting AUTO_INCREMENT at all. So, I think this is not related to MDEV-12836 create table t1 (a int not null, unique key a_key (a)) engine=innodb; insert into t1 values (19), (1), (100500); alter table t1 modify a int not null auto_increment,algorithm=instant; drop table t1; In this modified test case we have ALTER_CHANGE_COLUMN_DEFAULT and ALTER_AUTO_INC which is can be done instantly now. And this is now the subject of MDEV-12836. > > here `alter table` modifies the data, actually generating auto-inc > values for all NULL columns. I don't think you can do that instantly. > You can only remove auto-inc instantly. And for that you don't need any > big changes, just modify Field::is_equal() to allow it: > > diff --git a/sql/field.cc b/sql/field.cc > --- a/sql/field.cc > +++ b/sql/field.cc > @@ -3507,7 +3507,7 @@ uint Field_new_decimal::is_equal(Create_field > *new_field) > return ((new_field->type_handler() == type_handler()) && > ((new_field->flags & UNSIGNED_FLAG) == > (uint) (flags & UNSIGNED_FLAG)) && > - ((new_field->flags & AUTO_INCREMENT_FLAG) == > + ((new_field->flags & AUTO_INCREMENT_FLAG) <= > (uint) (flags & AUTO_INCREMENT_FLAG)) && > (new_field->length == max_display_length()) && > (new_field->decimals == dec)); > @@ -9508,7 +9508,7 @@ uint Field_num::is_equal(Create_field *new_field) > return ((new_field->type_handler() == type_handler()) && > ((new_field->flags & UNSIGNED_FLAG) == > (uint) (flags & UNSIGNED_FLAG)) && > - ((new_field->flags & AUTO_INCREMENT_FLAG) == > + ((new_field->flags & AUTO_INCREMENT_FLAG) <= > (uint) (flags & AUTO_INCREMENT_FLAG)) && > (new_field->pack_length == pack_length())); > } > > And this should be enough. > > Regards, > Sergei > Chief Architect MariaDB > and secur...@mariadb.org -- Eugene _______________________________________________ Mailing list: https://launchpad.net/~maria-developers Post to : maria-developers@lists.launchpad.net Unsubscribe : https://launchpad.net/~maria-developers More help : https://help.launchpad.net/ListHelp
