Until recently, we believed that range tombstones we read from sstables will
always be for entire rows (or more generalized clustering-key prefixes),
not for arbitrary ranges. But as we found out, because Cassandra insists
that range tombstones do not overlap, it may take two overlapping row
tombstones and convert them into three range tombstones which look like
general ranges (see the patch for a more detailed example).
Not only do we need to accept such "split" range tombstones, we also need
to convert them back to our internal representation which, in the above
example, involves two overlapping tombstones. This is what this patch does.
This patch also contains a test for this case: We created in Cassandra
an sstable with two overlapping deletions, and verify that when we read
it to Scylla, we get these two overlapping deletions - despite the
sstable file actually having contained three non-overlapping tombstones.
Signed-off-by: Nadav Har'El <nyh@scylladb.com>
Message-Id: <b7c07466074bf0db6457323af8622bb5210bb86a.1459399004.git.glauber@scylladb.com>