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From "Vijay (Updated) (JIRA)" <j...@apache.org>
Subject [jira] [Updated] (CASSANDRA-3762) AutoSaving KeyCache and System load time improvements.
Date Mon, 23 Jan 2012 23:25:40 GMT

     [ https://issues.apache.org/jira/browse/CASSANDRA-3762?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
]

Vijay updated CASSANDRA-3762:
-----------------------------

    Attachment: 0001-SavedKeyCache-load-time-improvements.patch

This patch will read the keys from the cache and sort it, so the index scan can be less impact
full on the MMaped index. 

Test (Not an extensive test but from my laptop):
100 Keys to be loaded into cache.

7G data file and 15M index (long type keys)
before the patch:
/var/log/cassandra/system.log:DEBUG [SSTableBatchOpen:4] 2012-01-23 15:10:40,825 SSTableReader.java
(line 196) INDEX LOAD TIME for /var/lib/cassandra/data/Keyspace2/Standard3/Keyspace2-Standard3-hc-2777:
850 ms.
after this patch:
/var/log/cassandra/system.log:DEBUG [SSTableBatchOpen:4] 2012-01-23 15:10:59,128 SSTableReader.java
(line 196) INDEX LOAD TIME for /var/lib/cassandra/data/Keyspace2/Standard3/Keyspace2-Standard3-hc-2777:
177 ms.
                
> 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-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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