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Date: Sun, 28 Feb 2010 16:42:20 +0100
Message-ID: <cadf1c691002280742h5c91fe47vd91a555400dd1b1e@mail.gmail.com>
Subject: Re: /_all_dbs and security
From: Filipe David Manana <fdmanana@gmail.com>
To: dev@couchdb.apache.org
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> this is the best reason I've heard for making it a security document. I
> wonder how much slower the 7.5k dbs scan proceeds when it has to look up
> documents instead of linked objects? do you mind adding a doc-read to the
> tight loop just to see what it does to performance?
>

$ time curl http://localhost:5984/_all_dbs | wc -l
  % Total    % Received % Xferd  Average Speed   Time    Time     Time
Current
                                 Dload  Upload   Total   Spent    Left
Speed
100  100k    0  100k    0     0    576      0 --:--:--  0:02:57 --:--:--
555
7397

real    2m57.811s
user    0m0.000s
sys    0m0.020s

Alot more as expected.


>
> the 7.5k thing isn't important once we have a _dbs db, but the cost it will
> expose as a benchmark will be proportional to the cost incurred on opening
> any db for any operation, and thus significant.
>

True. Traversing the b-tree of _dbs to find if a particular doc exists, and
then eventually insert it (which could imply re-balancing  the tree from
time to time) would take several disk accesses.

Any other ideas on how to implement _all_dbs efficiently?

cheers


-- 
Filipe David Manana,
fdmanana@gmail.com
PGP key - http://pgp.mit.edu:11371/pks/lookup?op=get&search=0xC569452B

"Reasonable men adapt themselves to the world.
Unreasonable men adapt the world to themselves.
That's why all progress depends on unreasonable men."

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