[TYPO3-performance] Slave DB results in TCE errors

[Dan Osipov]

Thanks for the idea! We have a lot of BE queries though, and would love 
to spread them out over slave servers as well.

Dan Osipov
http://danosipov.com/blog/

Roland Behme wrote:
> Hello Dan,
> 
>> The problem I'm experiencing in using the backend with this
>> configuration, is that saving any record generates an error:
>> 102: These fields are not properly updated in database: (list of field)
>> Probably value mismatch with fieldtype.
> We had the same problem with t3p_scalable and solved it by adding a 
> patch to ux_t3lib_DB->exec_SELECTquery() so that only the master server 
> is used for select queries when the user has a backend session.
> 
> The problem seems to occur because the synchronization between the 
> master and slave DB servers does not really happen in realtime, so the 
> change might not be applied yet when querying a random slave server 
> immediately after an update or insert.
> 
> I contributed the changes to the author of t3p_scalable almost a year 
> ago but I am not sure if he committed it to TER yet.
> 
> Hope this helps.
> 
> Best regards,
>   Roland