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Yang Yang edited comment on CASSANDRA-2735 at 6/17/11 9:47 PM:
---------------------------------------------------------------
there could be a problem with trying to rely on forcing compaction order to
make counter expiration work:
if you base the intended order on max timestamp of each sstable, the timestamp
is not trustworthy, because a single malicious client request can bump up its
timestamp to the future, and arbitrarily change the order of compaction, thus
rendering the approach in 2735 useless.
you can't base the order on the physical sstable flush time either, since
different nodes have different flush times.
overall I think trying to fix the compaction order is not the correct direction
to attack this problem: the issue here is due to the changing order between
*individual* counter adds/deletes (auto-expire is same as delete), this order
can be different between different counters, so you have to fix the order
between the updates within each counter, not the order between *ensembles of
counters*. such ensembles of counters do not guarantee any orders at all, due
to randomness in flushing time, or message delivery (they have similar effects)
was (Author: yangyangyyy):
there could be a problem with trying to rely on forcing compaction order to
make counter expiration work:
if you base the intended order on max timestamp of each sstable, the timestamp
is not trustworthy, because a single malicious client request can bump up its
timestamp to the future, and arbitrarily change the order of compaction, thus
rendering the approach in 2735 useless.
you can't base the order on the physical sstable flush time either, since
different nodes have different flush times.
overall I think trying to fix the compaction order is not the correct direction
to attack this problem: the issue here is due to the changing order between
individual counter adds/deletes (auto-expire is same as delete), this order can
be different between different counters, so you have to fix the order between
the updates within each counter, not the order between ensembles of counters.
such ensembles of counters do not guarantee any orders at all, due to
randomness in flushing time, or message delivery (they have similar effects)
> Timestamp Based Compaction Strategy
> -----------------------------------
>
> Key: CASSANDRA-2735
> URL: https://issues.apache.org/jira/browse/CASSANDRA-2735
> Project: Cassandra
> Issue Type: New Feature
> Components: Core
> Reporter: Alan Liang
> Assignee: Alan Liang
> Priority: Minor
> Labels: compaction
> Attachments: 0004-timestamp-bucketed-compaction-strategy.patch
>
>
> Compaction strategy implementation based on max timestamp ordering of the
> sstables while satisfying max sstable size, min and max compaction
> thresholds. It also handles expiration of sstables based on a timestamp.
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