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https://issues.apache.org/jira/browse/CASSANDRA-3762?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13264657#comment-13264657
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Vijay edited comment on CASSANDRA-3762 at 4/30/12 1:37 AM:
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>>> We can't require caches drop from users if they want to update to the newer
>>> version, imagine if users had a big caches and they would expect them to be
>>> warmed up to serve traffic from the beginning (good user experience on
>>> system start-up).
We can add versioning and support the older cache files and the newer ones we
can deserialize an additional byte about the promoted keys.
I was not sure if it is worth it because moving forward we are going to let the
keycache fault fill for the newer SST's, If we feel strongly about not dropping
the keys i can add logic to it.
>>> Also I don't think that (de-)serializer logic, is really needed because we
>>> would have sufficient data inside of the cache file to pre-load cache with
>>> one simple algorithm (in pseudo-code)
In the current way Descriptor is just a reference and if you want to construct
it is an additional overhead :), and in the row cache we dont have the values
of the row cache and we have to query ColumnFamilyStore.
was (Author: [email protected]):
>>> We can't require caches drop from users if they want to update to the
newer version, imagine if users had a big caches and they would expect them to
be warmed up to serve traffic from the beginning (good user experience on
system start-up).
We can add versioning and support the older cache files and the newer ones we
can deserialize an additional byte about the promoted keys.
I was not sure, if it was worth it as moving forward we are going to let the
keycache fault fill for the newer SST's. If we feel strongly about not dropping
the keys i can add logic to it.
>>> Also I don't think that (de-)serializer logic, is really needed because we
>>> would have sufficient data inside of the cache file to pre-load cache with
>>> one simple algorithm (in pseudo-code)
In the current way Descriptor is just a reference and if you want to construct
it is an additional overhead :), and in the row cache we dont have the values
of the row cache and we have to query ColumnFamilyStore.
> 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-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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