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From "Jon Haddad (JIRA)" <j...@apache.org>
Subject [jira] [Commented] (CASSANDRA-14496) TWCS erroneously disabling tombstone compactions
Date Tue, 05 Jun 2018 16:28:00 GMT

    [ https://issues.apache.org/jira/browse/CASSANDRA-14496?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=16502045#comment-16502045
] 

Jon Haddad commented on CASSANDRA-14496:
----------------------------------------

I'm not a fan of enabling them by default.  There's no value for the frequency that make any
sense at all given that a TTL could either be 5 minutes or 5 years.   

If someone supplies the {{tombstone_compaction_interval}} I suppose it wouldn't be unreasonable
to enable them.

> TWCS erroneously disabling tombstone compactions
> ------------------------------------------------
>
>                 Key: CASSANDRA-14496
>                 URL: https://issues.apache.org/jira/browse/CASSANDRA-14496
>             Project: Cassandra
>          Issue Type: Bug
>          Components: Compaction
>            Reporter: Robert Tarrall
>            Priority: Minor
>
> This code:
> {code:java}
> this.options = new TimeWindowCompactionStrategyOptions(options);
> if (!options.containsKey(AbstractCompactionStrategy.TOMBSTONE_COMPACTION_INTERVAL_OPTION)
&& !options.containsKey(AbstractCompactionStrategy.TOMBSTONE_THRESHOLD_OPTION))
> {
> disableTombstoneCompactions = true;
> logger.debug("Disabling tombstone compactions for TWCS");
> }
> else
> logger.debug("Enabling tombstone compactions for TWCS");
> }
> {code}
> ... in TimeWindowCompactionStrategy.java disables tombstone compactions in TWCS if you
have not *explicitly* set either tombstone_compaction_interval or tombstone_threshold. 
Adding 'tombstone_compaction_interval': '86400' to the compaction stanza in a table definition
has the (to me unexpected) side effect of enabling tombstone compactions. 
> This is surprising and does not appear to be mentioned in the docs.
> I would suggest that tombstone compactions should be run unless these options are both
set to 0.
> If the concern is that (as with DTCS in CASSANDRA-9234) we don't want to waste time on
tombstone compactions when we expect the tables to eventually be expired away, perhaps we
should also check unchecked_tombstone_compaction and still enable tombstone compactions if
that's set to true.
> May also make sense to set defaults for interval & threshold to 0 & disable
if they're nonzero so that setting non-default values, rather than setting ANY value, is what
determines whether tombstone compactions are enabled?



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