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https://issues.apache.org/jira/browse/CASSANDRA-1966?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=12980493#action_12980493
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Chris Burroughs commented on CASSANDRA-1966:
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I don't understand your comment about 10% of the cache being basically useless.
Wouldn't this depend on the size of the cache, time to read rows,
distribution of requests, etc.?
At least in my case I have small rows and and a row cache sized to 400,000
items. With a cold cache a large (most?) numbers of pending tasks in the
ROW-READ-STAGE are dropped (this lasts for 10s of minutes). While the node has
obviously joined the cluster at this point I would not consider it functional.
Once the cache reaches around 30,000 items with a RecentHitRate around 30%
ROW-READ-STAGE tasks stop being dropped. Once the row cache fills at 400,000
the recent RecentHitRate hovers close to 40% (as expected diminished returns).
30,000 is 7.5% of the cache.
> Option to control how many items are read on cache load
> -------------------------------------------------------
>
> Key: CASSANDRA-1966
> URL: https://issues.apache.org/jira/browse/CASSANDRA-1966
> Project: Cassandra
> Issue Type: Improvement
> Components: Core
> Reporter: Chris Burroughs
>
> CASSANDRA-1417 added an option to save the key and/or row cache keys which is
> cool. However, for a row large cache it can take a long time to read all of
> the rows. For example I have a 400,000 item row cache, and loading that on
> restart takes a little under an hour.
> In addition to configuring the size of the row cache, and how often it should
> be saved to disk, I propose an option to control how many items are loaded on
> startup (or alternately only saving n items out of the full row cache to
> begin with).
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