swuferhong commented on PR #3623:
URL: https://github.com/apache/fluss/pull/3623#issuecomment-4988737514

   > Thanks for working on this. After reviewing the changes, I have a couple 
of questions:
   > 
   > 1. Without this PR, if we set table.log.tiered.local-segments = 1, would 
that achieve the same goal as this PR?
   > 2. It looks like this PR does not roll the active segment for 
historical/inactive partitions.
   
   Hi, @zuston. Based on the offline discussion with @gyang94 , implementing 
TTL for the active segment in the short term is fairly tricky and requires a 
detailed design—but that doesn't mean it shouldn't be done. You can continue 
working on this in a follow-up PR.
   
   Regarding whether it can be set to `table.log.tiered.local-segments = 1`: 
these are two completely different concepts. One is about how much local data 
to reserve as a local read cache, and the other is about how long data should 
be retained before TTL kicks in. Consider the following scenario: the user has 
an hourly-partitioned table where partitions are retained for 24 hours, the log 
TTL is set to 1 hour, and the number of local segments is 5 (to ensure that the 
most recent hour of appended data stays on the server). In this case, the 
historical 23 hours would incur a large amount of redundant storage—even though 
the user has configured the log TTL to 1 hour.


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