Loading SSTables from the main directory is possible, to be compatible with
Cassandra, but extremely dangerous and not recommended.
From the beginning, we recommend using an separate, upload/ directory.
In all this time, perhaps due to how the feature's usefulness is reduced
in Cassandra due to the possible races, I have never seen anyone coming
from Cassandra doing procedures involving refresh at all.
Loading SSTables from the main directory forces us to disable writes to
the table temporarily until the SSTables are sorted out. If we get rid of
this, we can get rid of the disabling of the writes as well.
We can't do it now because if we want to be nice to the odd user that may
be using refresh through the main directory without our knowledge we should
at least error out.
This patch, then, does that: it errors out if SSTables are found in the main
directory. It will not proceed with the refresh, and direct the user to the
upload directory.
The main loop in reshuffle_sstables is left in place structurally for now, but
most of it is gone. The test for is is deleted.
After a period of deprecation we can start ignoring these SSTables and get rid
of the lock.
Signed-off-by: Glauber Costa <glauber@scylladb.com>
Message-Id: <20200429144511.13681-1-glauber@scylladb.com>
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