[wp-hackers] MySQL Replication Latency Issues in wp-admin pages

[Dion Hulse (dd32)]

Another solution (Which I'm not sure how to achieve) would be to switch All
reads/writes to the master upon is_admin() & SQL is Update/insert, That way
you retain as many reads to the slaves as possible, but once the wp-admin
decides to make a write, all future reads come from the only source that is
guarantee'd to be uptodate.

On 17 January 2011 12:37, dave morris <dvmorris at gmail.com> wrote:

> I have an environment running WP 3.0.1 with a Master db and two
> slaves. I am using HyperDB to force all writes to go to the Master,
> and all reads to read from the two slaves.
>
> I am experiencing a variety of issues in wp-admin pages where data is
> being written to the master, and WordPress attempts to read from a
> slave, and the data has not reached the slave yet. An example of this
> is when I hook 'dbx_post_advanced' to preset some category and custom
> taxonomy terms on new posts. I have verified that when I configure
> HyperDB to read and write from the Master alone, the
> 'dbx_post_advanced' hook works fine.
>
> I'm looking into the following options:
>
> * Dedicate only one web server to all wp-admin (aka back office)
> traffic
> ** Configure that server to read and write to/from the Master db only
> ** Configure the load balancer to route all /wp-admin url's to that
> web server
>
> * Configure HyperDB to read/write against the Master only for wp-admin
> pages
>
> * Setup MySQL Semisynchronous Replication
> ** http://dev.mysql.com/doc/refman/5.5/en/replication-semisync.html
> ** This solution will most likely not work, however, because
> semisynchronous replication will only wait until ONE slave has
> completed its writes, not both slaves in my case
>
> Let me know if you have any advice for this issue.
>
> Thanks,
> Dave
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