Hi, Eugene! On Feb 04, Eugene Kosov wrote:
revision-id: f93af1f93e2 (mariadb-10.3.12-19-gf93af1f93e2) parent(s): d4144c8e010 author: Eugene Kosov <claprix@yandex.ru> committer: Eugene Kosov <claprix@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 `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 security@mariadb.org