Re: how to adjust auto increment id offset?

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От Yan Chunlu
Тема Re: how to adjust auto increment id offset?
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Msg-id CAOA66tFFESM8vCwv=YPjRu1TB3_nr-r52Qi46JSQkZXDYLa=Xg@mail.gmail.com
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Ответ на Re: how to adjust auto increment id offset?  (John R Pierce <pierce@hogranch.com>)
Ответы Re: how to adjust auto increment id offset?  (Scott Marlowe <scott.marlowe@gmail.com>)
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thanks a lot for the tip!

sorry for used the wrong word, it is just multi-master but not sharding,  I would like to setup two master server across two datacenter.  one's id increased by 1, and the other by 2.  
so I could have a queue sync the record in the background by myself.  kind of a dumb way but it seems they only choice for me,  the delay within several minutes is acceptable.

On Tue, Nov 15, 2011 at 5:12 PM, John R Pierce <pierce@hogranch.com> wrote:
On 11/15/11 12:56 AM, Bèrto ëd Sèra wrote:
Hi


On 15 November 2011 11:44, Yan Chunlu <springrider@gmail.com <mailto:springrider@gmail.com>> wrote:

   I would like to implement two master db with even-odd id sharding.
     in mysql it is fairly easy by using the configuration:

   auto_increment_offset = 1
   auto_increment_increment = 2


   but I have searched a lot didn't find anything related to this,
   some users doing this via trigger like "rubyrep".

   is there an easy way to do this?  thanks!


http://www.postgresql.org/docs/8.1/static/sql-createsequence.html



also see ALTER SEQUENCE.

basically, you'll need to fix up every sequence (these are created automatically if you have fields of type SERIAL)....   on your 2nd server,

   ALTER SEQUENCE somesequencename INCREMENT BY 2 RESTART WITH 2;

and on your 1st server,

   ALTER SEQUENCE somesequencename INCREMENT BY 2;

do this before inserting any data.

thats a fairly unusual sharding technique, how do you plan on doing queries across both sets of data?


--
john r pierce                            N 37, W 122
santa cruz ca                         mid-left coast



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