[pybsddb] Making calls to keys() more efficient (or, how to do inequality gets on keys?)

[Jesus Cea]

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On 10/06/10 18:13, Jeremy Fishman wrote:
> FYI, memcached specifically limits the number of keys you can query from
> a bucket in one go (to a 2MB response), and does not support range
> queries (on keys), so it is often not possible to dump the entire
> cache's keys.

If you are actually using so many keys, you can use range key request in
Berkeley DB. I am not sure we support it yet in pybsddb. I can not check
it now. But if not, and you need it, just ask and I would add it to the
new pybsddb version.

PS: In my previous email I suggested you use cursors to check and delete
the oldest key in a btree database. If your deletion involves a lot of
keys, you could delete them when moving the cursor, or cache the keys to
delete in memory and then do a mass delete.

The performance depends of your specifics. But everything is better than
a blind "keys()", that would iterate over ALL the database... Unless the
database is really small or cached in RAM :).

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