cassandra-commits mailing list archives

Site index · List index
Message view « Date » · « Thread »
Top « Date » · « Thread »
From "Brandon Williams (JIRA)" <j...@apache.org>
Subject [jira] Issue Comment Edited: (CASSANDRA-1839) Keep a tombstone cache
Date Mon, 13 Dec 2010 20:29:03 GMT

    [ https://issues.apache.org/jira/browse/CASSANDRA-1839?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=12971023#action_12971023
] 

Brandon Williams edited comment on CASSANDRA-1839 at 12/13/10 3:28 PM:
-----------------------------------------------------------------------

I see, but that is only if we are proactively populating the cache.  I was thinking we would
do it after the first merge-on-read that resulted in a row-level tombstone.  Essentially what
row cache is doing now, but cheaper.

      was (Author: brandon.williams):
    I see, but that is only if we are proactively populating the cache.  I was thinking we
would do it after the first merge-on-read that resulted in a row-level tombstone.
  
> Keep a tombstone cache
> ----------------------
>
>                 Key: CASSANDRA-1839
>                 URL: https://issues.apache.org/jira/browse/CASSANDRA-1839
>             Project: Cassandra
>          Issue Type: New Feature
>          Components: Core
>    Affects Versions: 0.3
>            Reporter: Brandon Williams
>            Priority: Minor
>
> There is a use case in production where the pattern is read-then-delete, where most of
the keys read will not exist, but be attempted many times.  If the key has never existed,
the bloom filter makes this operation cheap, however if the key has existed, especially if
it has been overwritten many times and thus spans multiple SSTables, the merge-on-read just
to end up with a tombstone can be expensive.  This can be mitigated with keycache and some
rowcache currently, but this can be further optimized by storing a sentinel value in the keycache
indicating that it's a tombstone, which we can invalidate on new writes to the row.

-- 
This message is automatically generated by JIRA.
-
You can reply to this email to add a comment to the issue online.


Mime
View raw message