Hello,
I'm investigating the transition of some of our column families from
Size Tiered -> Leveled Compaction. I believe we have some
high-read-load column families that would benefit tremendously.
I've stood up a test DB Node to investigate the transition. I
successfully alter the column family, and I immediately noticed a large
number (1000+) pending compaction tasks become available, but no
compaction get executed.
I tried running "nodetool sstableupgrade" on the column family, and the
compaction tasks don't move.
I also notice no changes to the size and distribution of the existing
SSTables.
I then run a major compaction on the column family. All pending
compaction tasks get run, and the SSTables have a distribution that I
would expect from LeveledCompaction (lots and lots of 10MB files).
Couple of questions:
1) Is a major compaction required to transition from size-tiered to
leveled compaction?
2) Are major compactions as much of a concern for LeveledCompaction as
their are for Size Tiered?
All the documentation I found concerning transitioning from Size Tiered
to Level compaction discuss the alter table cql command, but I haven't
found too much on what else needs to be done after the schema change.
I did these tests with Cassandra 1.1.9.
Thanks,
-Mike
