Christian Spriegel created CASSANDRA-4917:
---------------------------------------------
Summary: Optimize tombstone creation for ExpiringColumns
Key: CASSANDRA-4917
URL: https://issues.apache.org/jira/browse/CASSANDRA-4917
Project: Cassandra
Issue Type: Improvement
Components: Core
Reporter: Christian Spriegel
The goal of this ticket is to reduce the amount of tombstones created from
ExpiringColumns.
Currently tombstones will always stay a full gc_grace time, which is not
neccessary for ExpiringColumns. We only need to ensure that ExpiringColumn and
tombstone together live as long as gc_grace. If the ExpiringColumn's
TTL>=gc_grace then we can create an already gcable tombstone and drop that
instantly.
My initial proposal was to use the ExpiringColumns creation-timestamp as
deletiontime for the tombstone, but Sylvain pointed out that we should not mix
local and client timestamps. So I changed it to this:
{code}
public static Column create(ByteBuffer name, ByteBuffer value, long timestamp,
int timeToLive, int localExpirationTime, int expireBefore,
IColumnSerializer.Flag flag)
{
if (localExpirationTime >= expireBefore || flag ==
IColumnSerializer.Flag.PRESERVE_SIZE)
return new ExpiringColumn(name, value, timestamp, timeToLive,
localExpirationTime);
// the column is now expired, we can safely return a simple tombstone
return new DeletedColumn(name, *localExpirationTime-timeToLive*, timestamp);
// return new DeletedColumn(name, localExpirationTime, timestamp); // old
code
}
{code}
This was discussed on the mailinglist:
http://cassandra-user-incubator-apache-org.3065146.n2.nabble.com/repair-compaction-and-tombstone-rows-td7583481.html
--
This message is automatically generated by JIRA.
If you think it was sent incorrectly, please contact your JIRA administrators
For more information on JIRA, see: http://www.atlassian.com/software/jira
