New batchlogs are written to the batchlog_v2 table and replay also uses
the v2 table.
The content of system.batchlog is attempted to be migrated to
system.batchlog_v2 after each start of the batchlog_manager service.
The migration is retried on each replay if it fails. This is reduntant
but simple.
Batchlog cleanup now doesn't involve flushing memtables, the only
remaining user of replica/database.hh is gone, so the include is
dropped.
Don't build batchlog delete mutations in storage-proxy code. Move this
code into db/batchlog_manager.cc, exposed via db/batchlog.hh.
This serves multiple goals:
1) Concentrates low-level batchlog related logic in
db/batchlog_manager.cc
2) Reduce current and future code duplication.
3) Make future changes to this logic easier.
Don't build batchlog mutations in storage-proxy code. Move this code
into db/batchlog_manager.cc, exposed via db/batchlog.hh.
This serves multiple goals:
1) Concentrates low-level batchlog related logic in
db/batchlog_manager.cc
2) Reduce current and future code duplication.
2) Make future changes to this logic easier.
