Some changes needed for the migration:
Postgres:
- Add default to five fields that have it in MySQL
- Make log_params not nullable
- Change log_comment_id and log_actor type to big integer
- Change log_namespace to integer
- Drop logging_actor_time index
MySQL/SQLite
- Change log_title to varbinary/BLOB
Bug: T230428
Bug: T164898
Change-Id: Iad59d2a78f61d93637917ca320d3e173863ce5e1
