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From "Hiram Chirino" <>
Subject Re: Kaha store
Date Mon, 10 Jul 2006 13:07:22 GMT
On 7/10/06, Rob Davies <> wrote:
> Something we need to address for the  Kaha persistent store is
> pluggable strategies for the indexing of data for both the List and
> Map container types.


Currently, an  IndexItem is a fixed size, but can be iterated as a bi-
> directional linked list. The IndexItem holds offsets to the the data
> value and optional data key which is held in rolling data logs. Data
> values/keys are variable in length.
> When a Container is loaded, the IndexItem is loaded in to an in-
> memory structure - so for a Map Container a Map will hold the key -
> the value being the IndexItem - so that getting a data value involves
> looking up the IndexItem - then retrieving the data value associated
> with the IndexItem from disk.
> This works reasonably well and is fine medium size collections of
> messages (~20-30million with the default heap size for a message
> broker).  But to ensure the Kaha Store can handle indexing larger
> number of messages with a relatively small memory footprint - we are
> obviously going to need something a little more sophisticated.
> Apart from a B-Tree - something that I've though about is using
> different types of caching - as the activemq message store really
> uses FIFO queues, a FIFO cache strategy would seem like a good
> strategy? thoughts ?


> Rob



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