Consider the following:
1) table A has N tablets and views
2) migration starts for a tablet of A from node 1 to 2.
3) migration is at write_both_read_old stage
4) coordinator will push writes to both nodes (pending and leaving)
5) A has view, so writes to it will also result in reads (table::push_view_replica_updates())
6) tablet's update_effective_replication_map() is not refreshing tablet sstable set (for new tablet migrating in)
7) so read on step 5 is not being able to find sstable set for tablet migrating in
Causes the following error:
"tablets - SSTable set wasn't found for tablet 21 of table mview.users"
which means loss of write on pending replica.
The fix will refresh the table's sstable set (tablet_sstable_set) and cache's snapshot.
It's not a problem to refresh the cache snapshot as long as the logical
state of the data hasn't changed, which is true when allocating new
tablet replicas. That's also done in the context of compactions for example.
Fixes#19052.
Fixes#19033.
Signed-off-by: Raphael S. Carvalho <raphaelsc@scylladb.com>
Closesscylladb/scylladb#19099