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From Damien Katz <>
Subject Re: /_all_dbs and security
Date Mon, 01 Mar 2010 15:52:22 GMT
Yes, server admins.


On Mar 1, 2010, at 7:50 AM, Filipe David Manana wrote:

> I assume your talking about server admins (those listed in the .ini file),
> right? If you're talking about DB admins, than the problem is the same
> (reading the _security object from each db file).
> On Mon, Mar 1, 2010 at 4:45 PM, Damien Katz <> wrote:
>> I don't think end users need a list of dbs they can access on the server.
>> Think the simplest answer is to only support _all_dbs operation for admins
>> and be done.
>> -Damien
>> On Mar 1, 2010, at 1:40 AM, Brian Candler wrote:
>>> On Mon, Mar 01, 2010 at 09:55:46AM +0100, Filipe David Manana wrote:
>>>>> The reason for no storing _security as a doc is an optimization. So we
>>>>> extend that optimization, and have something like a  security_changed
>> event
>>>>> for a db, that the _dbs database can react to. The model isn't
>> different
>>>>> from subscribing to _changes, it'd just be a separate code path.
>>>> That's a good idea (both simple and more efficient).
>>>> The only issues left are the cases where the user adds a new DB file
>>>> (possibly coming from other server for e.g.) into the DB dir, deletes a
>> DB
>>>> file or replaces a DB file with an old version (a backup whose update
>> seq
>>>> number is from the past).
>>> ...
>>>> Do you think this would add too much overhead or it could be a somewhat
>>>> "light" approach? Or better, do you have a better idea for it?
>>> Just as an idea, you could just turn this on its head. Suppose _dbs was
>> the
>>> primary source of information; then the _security record within the
>> database
>>> is just a cached copy of that.  It's easy enough to take a _changes feed
>>> from _dbs to update this cache.
>>> But in that case, the cache would be better kept in RAM, rather than
>> within
>>> the database file.
>>> After all, CouchDB already keeps a cache of open database filehandles,
>>> doesn't it?  So you could read the security information from a regular
>>> document (an "expensive" operation) when you open the database, and then
>>> just continue to use that version thereafter.  You'd invalidate the cache
>> if
>>> the corresponding _dbs object is updated.
>>> However this leaves the following issue: what if the database file is
>>> renamed on disk, or disk-copied to a different system which happens to
>> have
>>> an existing _dbs entry for that name?
>>> I think the best solution is for the _dbs database to be indexed by uuid.
>>> But to make this work efficiently, the database file *on disk* should
>> also
>>> be named by its uuid, rather than the database name.  That's probably too
>>> big a change to swallow at this stage.
>>> But it does have some other side benefits (such as being able to "rename"
>> a
>>> database instantly without touching the filesystem, and being able to
>>> automatically spread a large number of databases across directories
>> without
>>> forcing the user to use database names like 00/xxx, 01/yyy, 02/zzz etc)
>>> Regards,
>>> Brian.
> -- 
> Filipe David Manana,
> PGP key -
> "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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