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From "Vijay (JIRA)" <j...@apache.org>
Subject [jira] [Commented] (CASSANDRA-3762) AutoSaving KeyCache and System load time improvements.
Date Thu, 03 May 2012 17:08:48 GMT

    [ https://issues.apache.org/jira/browse/CASSANDRA-3762?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13267589#comment-13267589
] 

Vijay commented on CASSANDRA-3762:
----------------------------------

>>> Why don't you serialize data (payload) of the caches
Well the payloads can be in GB's when using Serialized cache and when you are trying to load
the old cache you will see inconsistencies between the cache save.
We cannot rely on shutdown hooks to make the data consistent because (http://docs.oracle.com/javase/1.5.0/docs/api/java/lang/Runtime.html#addShutdownHook(java.lang.Thread))
OS has timeouts on the shutdown and it doesnt help it when there are power failures. The main
problem with the RowCache Values are that they are mutable and Keycache values are immutable.

The main pain is during startup is keycache, but i dont see why it will be a pain to load
the rowcache.


                
> AutoSaving KeyCache and System load time improvements.
> ------------------------------------------------------
>
>                 Key: CASSANDRA-3762
>                 URL: https://issues.apache.org/jira/browse/CASSANDRA-3762
>             Project: Cassandra
>          Issue Type: Improvement
>          Components: Core
>    Affects Versions: 1.2
>            Reporter: Vijay
>            Assignee: Vijay
>            Priority: Minor
>             Fix For: 1.2
>
>         Attachments: 0001-CASSANDRA-3762-v2.patch, 0001-CASSANDRA-3762-v3.patch, 0001-SavedKeyCache-load-time-improvements.patch
>
>
> CASSANDRA-2392 saves the index summary to the disk... but when we have saved cache we
will still scan through the index to get the data out.
> We might be able to separate this from SSTR.load and let it load the index summary, once
all the SST's are loaded we might be able to check the bloomfilter and do a random IO on fewer
Index's to populate the KeyCache.

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