In Queens - which uses MariaDB 10.1 - the internal storage format used
for InnoDB tables is the 'COMPACT' format [1]. Whereas in Train -
which uses Mariadb 10.3 - the default storage format has changed from
'COMPACT' to 'DYNAMIC'. This means the Openstack tables internally use
different storage format whether they are created in Queens or in
Train.
During an FFU from Queens to Train, the database's internal tables
are upgraded with mysql_upgrade, but that tool doesn't ALTER the
Openstack tables to use the new default internal storage format
as it is not needed when upgrading the database.
Mariadb 10.3 has more DDL checks that Mariadb 10.1, such as for example
stricter table create/alter checks and table size checks. And recent
Mariadb (e.g. 10.3.27) has changed the severity of some of those checks
when InnoDB strict mode is enforced (the default). Consequently,
some checks are failing with a few OpenStack tables after the FFU
has upgraded the database without changing the row format in use, which
at least breaks some db_sync containers:
[root@controller-0 stdouts]# more nova_db_sync.log
2020-12-14T11:54:54.186418426+00:00 stdout F ERROR: Could not access cell0.
2020-12-14T11:54:54.186418426+00:00 stdout F Has the nova_api database been created?
2020-12-14T11:54:54.186418426+00:00 stdout F Has the nova_cell0 database been created?
2020-12-14T11:54:54.186418426+00:00 stdout F Has "nova-manage api_db sync" been run?
2020-12-14T11:54:54.186418426+00:00 stdout F Has "nova-manage cell_v2 map_cell0" been run?
2020-12-14T11:54:54.186418426+00:00 stdout F Is [api_database]/connection set in nova.conf?
2020-12-14T11:54:54.186418426+00:00 stdout F Is the cell0 database connection URL correct?
2020-12-14T11:54:54.186418426+00:00 stdout F Error: (pymysql.err.InternalError) (1118, 'Row size too large. The maximum row size for the used table type, not counting BLOBs, is 8126. This includes storage overhead, check the manual.
You have to change some columns to TEXT or BLOBs')
2020-12-14T11:54:54.186418426+00:00 stdout F [SQL:
2020-12-14T11:54:54.186418426+00:00 stdout F ALTER TABLE instances ADD hidden BOOL]
2020-12-14T11:54:54.186418426+00:00 stdout F (Background on this error at: http://sqlalche.me/e/2j85)
[1] https://mariadb.com/kb/en/innodb-row-formats-overview/
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