[
https://issues.apache.org/jira/browse/CASSANDRA-7331?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
]
sankalp kohli resolved CASSANDRA-7331.
--------------------------------------
Resolution: Won't Fix
> Improve Droppable Tombstone compaction
> --------------------------------------
>
> Key: CASSANDRA-7331
> URL: https://issues.apache.org/jira/browse/CASSANDRA-7331
> Project: Cassandra
> Issue Type: Improvement
> Components: Core
> Reporter: sankalp kohli
> Priority: Minor
> Labels: compaction
>
> I was thinking about this idea so creating a JIRA to discuss it.
> Currently we do compaction for stables which have more than configurable
> number of droppable tombstones.
> Also there is another JIRA CASSANDRA-7019 to do compactions involving
> multiple stables from different levels which will be triggered based of same
> threshold.
> One of the areas of improvement here to pick better candidates will be to
> find out if a tombstone can actually get rid of data in other stables.
> We can add a byte to tombstone to keep track of whether it has knocked off
> the actual data(for which it is there) or not.
> All tombstones will start out with 0 as its value. When it compacts with
> other stables and causes data to be deleted, it will be incremented.
> For cases where there are multiple updates and then a delete, this value can
> be more than 1 depending on how many updates came in before delete.
> If we have this, by looking at these numbers in tombstones, we can find a
> stable which by compacting, we will get rid of maximum data. We can also add
> a global number per stable which sums up these numbers.
> I am not sure how this will work with range tombstones and whether this will
> be useful.
--
This message was sent by Atlassian JIRA
(v6.3.4#6332)
