In addition to what Jeff mentioned, there was an optimization in 3.4 that
can significantly reduce the number of sstables accessed when a LIMIT
clause was used. This can be a pretty big win with TWCS.
In my original TWCS talk a few years back, I suggested that people make the
partitions match the time window to avoid exactly what you’re describing. I
added that to the talk because my first team that used TWCS (the team for which
I built TWCS) had a data model not unlike yours, and the
Situation:
We use TWCS for a task history table (partition is user, column key is
timeuuid of task, TWCS is used due to tombstone TTLs that rotate out the
tasks every say month. )
However, if we want to get a "slice" of tasks (say, tasks in the last two
days and we are using TWCS sstable blocks
