Split compaction divides the partitions in an existing sstable into two
groups and writes them into two new sstables, which replace the original
one. The partition count from the original sstable is used as an
estimate when writing the new ones, but this estimate is not accurate as
the partitions are split between the two new sstables and each will
contain only a portion of the original partition count. This also causes
the bloom filters to be rebuilt at the end of compaction, as they were
initially built with inaccurate estimates.
Fix this by using a better estimate for the output sstables based on the
token ranges written to them.
Fixes scylladb#20253
Signed-off-by: Lakshmi Narayanan Sreethar <lakshmi.sreethar@scylladb.com>
eb4b407085