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From "Jonathan Ellis (JIRA)" <>
Subject [jira] [Commented] (CASSANDRA-5357) Query cache
Date Tue, 09 Apr 2013 15:52:16 GMT


Jonathan Ellis commented on CASSANDRA-5357:

bq. What i had in mind was to do something like Map<RowKey, [QueryFilter,ColumnFamily]>
so invalidation is O(1). To further improve the performance on a query (And deserializing
the whole [QueryFilter,ColumnFamily] we can have all the QueryFilters as a part of the RowKey
(Kind of like promoted index's).

I don't follow -- how can you have both O(1) [Map key is the row key] and also promote QF
into the key?

bq. If we do this then the K (For a fat row) becomes big enough to cause more heap issue.
Hence we could move that to off-heap along with CF.

We're talking about K=Map Key, right?  How do you see QF increasing by row size?

> Query cache
> -----------
>                 Key: CASSANDRA-5357
>                 URL:
>             Project: Cassandra
>          Issue Type: Bug
>            Reporter: Jonathan Ellis
>            Assignee: Vijay
> I think that most people expect the row cache to act like a query cache, because that's
a reasonable model.  Caching the entire partition is, in retrospect, not really reasonable,
so it's not surprising that it catches people off guard, especially given the confusion we've
inflicted on ourselves as to what a "row" constitutes.
> I propose replacing it with a true query cache.

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