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From "Stu Hood (JIRA)" <>
Subject [jira] Commented: (CASSANDRA-1417) add cache save/load
Date Sun, 22 Aug 2010 02:08:17 GMT


Stu Hood commented on CASSANDRA-1417:

Could this be stored in the statistics column family that was added in 0.7?

> add cache save/load
> -------------------
>                 Key: CASSANDRA-1417
>                 URL:
>             Project: Cassandra
>          Issue Type: New Feature
>          Components: Core
>            Reporter: Jonathan Ellis
>             Fix For: 0.6.6, 0.7 beta 2
> Since mixing 0.7 nodes with 0.6 is looking increasingly unlikely to be supported because
of the deep changes to the Thrift API, we should allow saving out the 0.6 cache and loading
it on startup so that we don't inflict the pain of an entire cluster of cold cache on upgraders.
> The cache format should just be a list of row keys.  Loading it is as simple as calling
getColumnFamily (with a zero-column predicate) on each row, for row cache.
> Key cache is more complicated, but only a little.  First is that you have to de-duplicate
the row keys from multiple sstables.  (Saving which sstable version it's associated with is
less useful, since that will be obsoleted by compaction.)  Second is that we don't need to
actually read any row data, we just need to go through the index locator part of the read
path (getPosition).

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