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https://issues.apache.org/jira/browse/CASSANDRA-3762?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13193936#comment-13193936
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Pavel Yaskevich commented on CASSANDRA-3762:
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bq. Why would that matter? Trunk reads the index even if there is 0/0 keys to
be loaded.... but for this test the comments for both the load is the same....
(because all i did was kept restarting in between dropping the cache). The
above comments are a sample of multiple restarts... They are relative to my
environment.
Because even if it reads the whole index when don't know how key cache pre-load
affects performance. Because with your results we can clearly see the thing I
was talking about - after this patch, key cache pre-load directly degrades
performance the bigger it gets.
> 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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