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Original message

Author Moritz Mertinkat <moritz@mertinkat.net>
Full name Moritz Mertinkat <moritz@mertinkat.net>
Date 2007-12-04 06:48:31 PST
Message Hi everybody,

I've just looked at the code and I think it's a great thing to add to propel.

What I think should be improved is that all slave connections get connected at
the moment Propel ist loaded. That is, if you have eight MySQL slave servers
you establish a MySQL connection to all of them, even though you just need one
(for example). Kinda slow :)

Wouldn't it be better to load just _one_ random slave upon starting?

Another problem with random-slave-per-query might occur when you're slaves are
not 100 % synchronized (i.e. some are a few seconds behind master).
I think a single page view should (in general) be handled by just one slave.

For those who (really) want to have a different slave each query one might add
a flag to Propel::init or to the configuration.

[Onother idea would be to tell Propel if you need read/write- or just
read-access to your database. In case you only need read-access it's
enough to connect _one_ a random slave (no master db is required).
Maybe both ideas together would make the perfect master-slave-propel :-]


Christian Abegg schrieb:
> Hi Hans
> - This will work fine without master/slave replication and it should not
> have any impact on a existing single db setup. Although I'd be glad for
> further testings or code reviews.
> - The changes in the Propel class primarly touch the "getConnection" method.
> I copied some code from it to that new "initConnection" method which can now
> be called multiple times from the "getConnection" method (i.e. for the
> master and its slaves).
> - Of course I'll document it.
> Please note that I've just tried it on a mysql replication setup. I'd be
> happy to run some tests. Do you have a test suite?
> Regards,
> Christian
> Hans Lellelid wrote:
>> Hi Christian,
>> Yes :)
>> Am I right in assuming that this will work fine without a master/slave
>> setup? (i.e. in traditional, single-db model?)
>> I didn't drop these in to do a diff, but the PropelPDO looked fairly
>> similar; Propel class too?
>> I'd like to get this added in, though. I think it would be a great
>> benefit.
>> Would you be willing to contribute some documentation on getting this
>> setup? -- e.g. in 1.3 user guide?
>> Thanks,
>> Hans
>> Christian Abegg wrote:
>>> hi there
>>> here's a refinend implementation of r/w splitting:
>>> http://www.nabble.co​m/file/p14116000/rwS​plitting.zip rwSplitting.zip
>>> anyone interested?
>>> regards
>>> christian
>>> Christian Abegg wrote:
>>>> hi cameron, dear devs
>>>> thank you for your reply. i made a first try to implement it the way you
>>>> proposed:
>>>> - the propel class initializes a PropelPDO object which acts as db
>>>> connection to the master server
>>>> - the PropelPDO object also holds an array of other PDO connections used
>>>> for read only queries
>>>> pro: realtively simple to implement, building up on the existing code
>>>> contra: PropelPDO extending PDO is no more used as a singe db connection
>>>> have a look at the two patches attached. they are a very first draft
>>>> showing the way I would choose.
>>>> http://www.nabble.co​m/file/p13820966/Pro​pel.diff Propel.diff
>>>> http://www.nabble.co​m/file/p13820966/Pro​pelPDO.diff PropelPDO.diff
>>>> please let me know if you'd appreciate any further work on that matter
>>>> and
>>>> if there are architectural changes/constraints to be considered.
>>>> cheers
>>>> christian
>>>> Cameron Brunner wrote:
>>>>> There is no reason this cant be done purely by slotting in a new
>>>>> PropelPDO layer with intelligence on what to send the query to IMO. I
>>>>> have thought this out before and it shouldn't be too painful depending
>>>>> upon just how smart you want it.
>>>>> On 11/3/07, Christian Abegg <abegg dot ch at gmail dot com> wrote:
>>>>>> hi
>>>>>> i'd like to use my propel app in an environment where the db-master is
>>>>>> replicated to one or more slave databases. the master gets the writing
>>>>>> statements, the slave gets the reading statements.
>>>>>> in my opinion, the propel layer would be appropriate implement that
>>>>>> function.
>>>>>> as far as i see, there is no such feature in propel.
>>>>>> after a short look into the generated base-classes, it seems like a
>>>>>> quite an easy task to implement a read-write splitting. assuming that
>>>>>> all reading queries call the "doSelectStmt" function, i'd introduce
>>>>>> the
>>>>>> DATABASE_NAME_READ-constant which points to the configuration of the
>>>>>> slave-db.
>>>>>> for load balancing between multiple slave-db's i'd use the
>>>>>> mysql-proxy.
>>>>>> but a simple round robin mechanism could be implemented in propel as
>>>>>> well.
>>>>>> i'm not sure wheter this approach could solve my problem. a big
>>>>>> question
>>>>>> is: are the connection objects cached by propel? or is the
>>>>>> $con-variable
>>>>>> always null if the user doesn't give a connection on the application
>>>>>> layer?
>>>>>> if that enhancement is considered usefull and could be implemented
>>>>>> within reasonable time, i'd be glad to help.
>>>>>> christian abegg
>>>>>> ps: my attempts to add an enhancement ticket failed beacaus they were
>>>>>> rejected as spam by trac.
>>>>>> --------------------​--------------------​--------------------​---------
>>>>>> To unsubscribe, e-mail: dev-unsubscribe@prop​el.tigris.org
>>>>>> For additional commands, e-mail: dev-help at propel dot tigris dot org
>>>>> --
>>>>> Cameron Brunner
>>>>> Want a better web browser?
>>>>> http://www.spreadfir​efox.com/?q=affiliat​es&id=182780​&t=1
>>>>> --------------------​--------------------​--------------------​---------
>>>>> To unsubscribe, e-mail: dev-unsubscribe@prop​el.tigris.org
>>>>> For additional commands, e-mail: dev-help at propel dot tigris dot org
>> --------------------​--------------------​--------------------​---------
>> To unsubscribe, e-mail: dev-unsubscribe@prop​el.tigris.org
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> --
> View this message in context: http://www.nabble.co​m/r-w-splitting-in-m​aster-slave-db-repli​cation-environment-t​f4740128.html#a14124​959
> Sent from the propel - dev mailing list archive at Nabble.com.