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Re: [propel-dev] r/w splitting in master-slave db replication environment

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Author Shane Langley <shane dot langley at gmail dot com>
Full name Shane Langley <shane dot langley at gmail dot com>
Date 2007-12-04 11:40:14 PST
Message "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."

I agree with this. The first time a connection to a slave is required a connection should be established to one slave, and stored as the "select" connection.

Subsequent selects should re-use that slave .

"[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 :-]"

The reverse works as well.

For an application I worked on I created a ConnectionMananger class that
handled the split between master/slave.

I added a method "forceMaster()" that would ensure every query would hit the master.

Some pages you want to have the most update-to-date data (when editing for example) loaded into
your form. Without this method, the data would come from a slave (since the select query is not in a transaction) which could be out-of-date by a few seconds.

In this case, you don't need a slave connection at all.

Regards,

Shane.

Moritz Mertinkat wrote:
> 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 :-]
>
> Regards,
> Moritz
>
>
> 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
>>> For additional commands, e-mail: dev-help at propel dot tigris dot org
>>>
>>>
>>>
>>>
>> --
>> 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.
>>
>>
>>
>
> --------------------​--------------------​--------------------​---------
> To unsubscribe, e-mail: dev-unsubscribe@prop​el.tigris.org
> For additional commands, e-mail: dev-help at propel dot tigris dot org
>
>
>

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r/w splitting in master-slave db replication environment Christian Abegg <abegg dot ch at gmail dot com> Christian Abegg <abegg dot ch at gmail dot com> 2007-11-02 13:09:28 PDT
     Re: [propel-dev] r/w splitting in master-slave db replication environment Cameron Brunner <cameron dot brunner at gmail dot com> Cameron Brunner <cameron dot brunner at gmail dot com> 2007-11-02 17:23:10 PDT
         Re: [propel-dev] r/w splitting in master-slave db replication environment Christian Abegg <abegg dot ch at gmail dot com> Christian Abegg <abegg dot ch at gmail dot com> 2007-11-18 08:59:06 PST
             Re: [propel-dev] r/w splitting in master-slave db replication environment Christian Abegg <abegg dot ch at gmail dot com> Christian Abegg <abegg dot ch at gmail dot com> 2007-12-02 06:26:12 PST
                 Re: [propel-dev] r/w splitting in master-slave db replication environment hlellelid Hans Lellelid 2007-12-02 17:22:35 PST
                     Re: [propel-dev] r/w splitting in master-slave db replication environment Christian Abegg <abegg dot ch at gmail dot com> Christian Abegg <abegg dot ch at gmail dot com> 2007-12-02 23:29:59 PST
                         Re: [propel-dev] r/w splitting in master-slave db replication environment hlellelid Hans Lellelid 2007-12-03 03:54:52 PST
                         Re: Re: [propel-dev] r/w splitting in master-slave db replication environment Moritz Mertinkat <moritz at mertinkat dot net> Moritz Mertinkat <moritz at mertinkat dot net> 2007-12-04 06:48:31 PST
                             Re: Re: [propel-dev] r/w splitting in master-slave db replication environment Pedram Nimreezi <zenstyle at gmail dot com> Pedram Nimreezi <zenstyle at gmail dot com> 2007-12-04 07:40:31 PST
                             Re: [propel-dev] r/w splitting in master-slave db replication environment Shane Langley <shane dot langley at gmail dot com> Shane Langley <shane dot langley at gmail dot com> 2007-12-04 11:40:14 PST
                                 Re: [propel-dev] r/w splitting in master-slave db replication environment Moritz Mertinkat <moritz at mertinkat dot net> Moritz Mertinkat <moritz at mertinkat dot net> 2007-12-04 12:11:38 PST
                                     Re: [propel-dev] r/w splitting in master-slave db replication environment Shane Langley <shane dot langley at gmail dot com> Shane Langley <shane dot langley at gmail dot com> 2007-12-04 12:48:15 PST
                                         Re: [propel-dev] r/w splitting in master-slave db replication environment hlellelid Hans Lellelid 2007-12-04 13:22:07 PST
                                             Re: [propel-dev] r/w splitting in master-slave db replication environment Christian Abegg <abegg dot ch at gmail dot com> Christian Abegg <abegg dot ch at gmail dot com> 2007-12-10 13:50:26 PST
                                         Re: [propel-dev] r/w splitting in master-slave db replication environment Moritz Mertinkat <moritz at mertinkat dot net> Moritz Mertinkat <moritz at mertinkat dot net> 2007-12-04 13:24:16 PST
                                             Re: [propel-dev] r/w splitting in master-slave db replication environment hlellelid Hans Lellelid 2008-01-04 05:57:21 PST
                                                 Re: [propel-dev] r/w splitting in master-slave db replication environment Christian Abegg <abegg dot ch at gmail dot com> Christian Abegg <abegg dot ch at gmail dot com> 2008-01-06 00:45:46 PST
                                                     Re: [propel-dev] r/w splitting in master-slave db replication environment hlellelid Hans Lellelid 2008-01-06 06:31:58 PST
                                                 Re: [propel-dev] r/w splitting in master-slave db replication environment =?ISO-8859-1?Q?David_Z=FClke?= <dz at bitxtender dot com> =?ISO-8859-1?Q?David_Z=FClke?= <dz at bitxtender dot com> 2008-01-07 06:46:19 PST
                                                     Re: [propel-dev] r/w splitting in master-slave db replication environment hlellelid Hans Lellelid 2008-01-07 06:47:37 PST
                                                         Re: [propel-dev] r/w splitting in master-slave db replication environment =?ISO-8859-1?Q?David_Z=FClke?= <dz at bitxtender dot com> =?ISO-8859-1?Q?David_Z=FClke?= <dz at bitxtender dot com> 2008-01-07 07:56:22 PST
                                                             Re: [propel-dev] r/w splitting in master-slave db replication environment hlellelid Hans Lellelid 2008-01-07 07:56:27 PST
                                                                 Re: [propel-dev] r/w splitting in master-slave db replication environment =?ISO-8859-1?Q?David_Z=FClke?= <dz at bitxtender dot com> =?ISO-8859-1?Q?David_Z=FClke?= <dz at bitxtender dot com> 2008-01-07 08:02:14 PST
                                                                     Re: [propel-dev] r/w splitting in master-slave db replication environment hlellelid Hans Lellelid 2008-01-07 08:06:02 PST
                                                                         Re: [propel-dev] r/w splitting in master-slave db replication environment =?ISO-8859-1?Q?David_Z=FClke?= <dz at bitxtender dot com> =?ISO-8859-1?Q?David_Z=FClke?= <dz at bitxtender dot com> 2008-01-07 08:32:56 PST
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