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From "Jonathan Ellis (Commented) (JIRA)" <j...@apache.org>
Subject [jira] [Commented] (CASSANDRA-3143) Global caches (key/row)
Date Thu, 15 Dec 2011 18:46:30 GMT

    [ https://issues.apache.org/jira/browse/CASSANDRA-3143?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13170400#comment-13170400
] 

Jonathan Ellis commented on CASSANDRA-3143:
-------------------------------------------

bq. I fail to see what is so crazy about having the function that saves the cache having access
to both key and value. It may require a bit of refactoring, but I don't see that as a good
argument. Anyway, it's not a very big deal but I still think that the two phase loading is
more fragile than it needs, and saving values would allow a proper reload.

Why would you want to do a cache reload?  That's just going to be stale...  Clearing the cache
I can understand, but reloading a semi-arbitrary older cache state?  I don't see the value
there.

ISTM we're talking about trading one kind of ugly code (passing around the Set of keys to
load to SSTR) for another (a lot of code duplication between key cache, which wants to save
values, and row cache, which doesn't).  It's also worth pointing out that if we're concerned
about cache size, the two-phase approach gives smaller saved caches.  So I think I'd lean
towards the existing, two-phase approach.
                
> Global caches (key/row)
> -----------------------
>
>                 Key: CASSANDRA-3143
>                 URL: https://issues.apache.org/jira/browse/CASSANDRA-3143
>             Project: Cassandra
>          Issue Type: Improvement
>            Reporter: Pavel Yaskevich
>            Assignee: Pavel Yaskevich
>            Priority: Minor
>              Labels: Core
>             Fix For: 1.1
>
>         Attachments: 0001-global-key-cache.patch, 0002-global-row-cache-and-ASC.readSaved-changed-to-abstra.patch,
0003-CacheServiceMBean-and-correct-key-cache-loading.patch, 0004-key-row-cache-tests-and-tweaks.patch,
0005-cleanup-of-the-CFMetaData-and-thrift-avro-CfDef-and-.patch, 0006-row-key-cache-improvements-according-to-Sylvain-s-co.patch,
0007-second-round-of-changes-according-to-Sylvain-comment.patch
>
>
> Caches are difficult to configure well as ColumnFamilies are added, similar to how memtables
were difficult pre-CASSANDRA-2006.

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