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From Thomas Mueller <muel...@adobe.com>
Subject Re: ids and locality
Date Wed, 12 Jan 2011 08:29:58 GMT
Hi,

>Only when the node id directly mapped to a storage location on a media
>that benefits from locality of access.

No. In fact, using a persistence manager that stores the *data* in an
append only way, the main performance problem (more than 80%) is index
access (for large repositories). That means, the order of (bundle) writes
closely matches the access order. Otherwise, accessing the data would take
a lot more time than accessing the index.

If the node id would directly map the storage location on a media, then
you would either need to do in-place-updates (which are very problematic
for many reasons), or you would always need to update all parent nodes
(including the root) if you update a node, which is also problematic,
specially if you store the data in a relational database.

Regards,
Thomas


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