For sealed SSTables we can get the maximum timestamp from the statistics
component. But for partially written SSTables, the metadata is not yet
available.
One way to solve this would be to make the SSTable statistics available
earlier. But we would end up with a maximum timestamp that potentially
changes all the time as we write more cells.
A better approach is to take note of what's the maximum timestamp in a
memtable before we start to flush, and when time comes for us to flush
we will use the progress manager to inform the consumers about the
maximum timestamp.
For SSTables being compacted, we can't know for sure what is the maximum
timestamp as some entries could be TTLd already. But the maximum of all
SSTables present in the compaction is a good enough estimation for this
purposes.
Signed-off-by: Glauber Costa <glauber@scylladb.com>
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