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From "Jonathan Ellis (JIRA)" <j...@apache.org>
Subject [jira] [Comment Edited] (CASSANDRA-6477) Partitioned indexes
Date Mon, 31 Mar 2014 16:51:18 GMT

    [ https://issues.apache.org/jira/browse/CASSANDRA-6477?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13955260#comment-13955260
] 

Jonathan Ellis edited comment on CASSANDRA-6477 at 3/31/14 4:49 PM:
--------------------------------------------------------------------

Sylvain had a different idea:

Instead of just writing a {{24, user1}} tombstone, write a tombstone that indicates what the
value changed to: {{24, user1 -> 25}} for one thread, and {{24, user1 -> 26}} for the
other.

When the tombstones are merged for compaction or read, you can say "wait 2 people tried to
erase that, one with 25 the other with 26, let's check which was has a higher timestamp and
delete any obsolete entries."



was (Author: jbellis):
Sylvain had a different idea:

Instead of just writing a {{24, user1}} tombstone, write a tombstone that indicates what the
value changed to: {{24, user1 -> 25}} for one thread, and {{24, user1 -> 26}} for the
other.

When the tombstones is merged for compaction or read, you can say "wait 2 people tried to
erase that, one with 25 the other with 26, let's check which was has a higher timestamp and
delete any obsolete entries."


> Partitioned indexes
> -------------------
>
>                 Key: CASSANDRA-6477
>                 URL: https://issues.apache.org/jira/browse/CASSANDRA-6477
>             Project: Cassandra
>          Issue Type: New Feature
>          Components: API, Core
>            Reporter: Jonathan Ellis
>             Fix For: 3.0
>
>
> Local indexes are suitable for low-cardinality data, where spreading the index across
the cluster is a Good Thing.  However, for high-cardinality data, local indexes require querying
most nodes in the cluster even if only a handful of rows is returned.



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