cassandra-commits mailing list archives

Site index · List index
Message view « Date » · « Thread »
Top « Date » · « Thread »
From "Jonathan Ellis (Commented) (JIRA)" <>
Subject [jira] [Commented] (CASSANDRA-3974) Per-CF TTL
Date Wed, 04 Apr 2012 19:24:22 GMT


Jonathan Ellis commented on CASSANDRA-3974:

Thanks Kirk!

My comments:

- Looks like this only updates the CQL path?  We'd want to make the Thrift path cf-ttl-aware
as well.  I *think* this just means updating RowMutation + CF addColumn methods.
- Nit: we could simplify getTTL a bit by adding assert ttl > 0.
- I got it backwards: we want max(cf ttl, column ttl) to be able to reason about the live-ness
of CF data w/o looking at individual rows
- We can break the compaction optimizations into another ticket.  It really needs a separate
compaction Strategy; the idea is if we have an sstable A older than CF ttl, then all the data
in the file is dead and we can just delete the file without looking at it row-by-row.  However,
there's a lot of tension there with the goal of normal compaction, which wants to merge different
versions of the same row, so we're going to churn a lot with a low chance of ever having an
sstable last the full TTL without being merged, effectively restarting our timer.  So, I think
we're best served by a ArchivingCompactionStrategy that doesn't merge sstables at all, just
drops obsolete ones, and let people use that for append-only insert workloads.  Which is a
common enough case that it's worth the trouble... probably. :)
> Per-CF TTL
> ----------
>                 Key: CASSANDRA-3974
>                 URL:
>             Project: Cassandra
>          Issue Type: New Feature
>            Reporter: Jonathan Ellis
>            Assignee: Kirk True
>            Priority: Minor
>             Fix For: 1.2
>         Attachments: trunk-3974.txt
> Per-CF TTL would allow compaction optimizations ("drop an entire sstable's worth of expired
data") that we can't do with per-column.

This message is automatically generated by JIRA.
If you think it was sent incorrectly, please contact your JIRA administrators:!default.jspa
For more information on JIRA, see:


View raw message