[TYPO3-performance] Slave DB results in TCE errors

[Roland Behme]

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