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https://issues.apache.org/jira/browse/CASSANDRA-14496?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=16502769#comment-16502769
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Robert Tarrall edited comment on CASSANDRA-14496 at 6/6/18 3:01 AM:
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BTW rereading my original ticket here, I see I totally failed to mention I had
enabled {{unchecked_tombstone_compaction}} ... which was really the key to why
I opened the ticket.
To hopefully clarify: if {{unchecked_tombstone_compaction}} is set to true,
tombstone compactions should be enabled, even in TWCS. We should not have to
also set interval or threshold in order to enable.
Also, it would probably be better to have maximally high default values for
interval and threshold to more correctly indicate default behavior. The
default isn't really 86400 and 0.2; it's "never". That's the right choice for
most TWCS users, but isn't clear from the docs.
was (Author: tarrall):
BTW rereading my original ticket here, I see I totally failed to mention
{{unchecked_tombstone_compaction}} which was really the key to why I opened the
ticket.
To hopefully clarify: if {{unchecked_tombstone_compaction}} is set to true,
tombstone compactions should be enabled, even in TWCS. We should not have to
also set interval or threshold in order to enable.
Also, it would probably be better to have maximally high default values for
interval and threshold to more correctly indicate default behavior. The
default isn't really 86400 and 0.2; it's "never". That's the right choice for
most TWCS users, but isn't clear from the docs.
> 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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