Two weeks ago, we reverted to a dump of the limesurvey database, and ever since we have been experiencing sporadic errors that all seem to be caused by missing data. In some cases survey questions or answers are missing, in others responses, and in at least one case one of the lime_survey_XXXX tables was missing a column.

The really weird thing is, a lot of this data also seems to be missing in older database dumps. For instance, I found the CREATE TABLE statement for the table with the missing column, but it does not have that column in it, and the binlogs do not show any ALTER statements that could have added it.

It appears that our backups are incomplete, but I don't understand how. We are backing up the entire database with mysqldump using the following flags: I know this is scant information to go on, but I was hoping maybe someone else with a similar experience has found a solution, or can point out what I'm missing.

Thanks

Which Limesurveyversion/build and which MySQL version is used?
Was Limesurvey updated? Perhaps a mismatch between running LS and the restored database?

You will have to check the configuration of MySQL/MariaDB.
Perhaps some defaults have been altered.
What engines are used? Only InnoDB? Is MyISAM used?
Problem is mostly that the restore and backup process is not showing warnings and errors, when parts are skipped.

Yes, of course...

Limesurvey 2.05+, MySQL 5.6.30, MyISAM.

There have been no recent updates. The only change introduced was to revert to a db dump that was only a few hours old. The dump itself appears intact, and loads without error, it just seems to be missing data.

Thanks

What is the build of LS 2.05+ ?

The bug can be in the backup or restore routine. No errors might be reported.
Just as an example, take a look at this bug.
Was reported 2014, but was fixed in 2016.
bugs.mysql.com/bug.php?id=71783
MySQL 5.6.31 got that fixed.

It could be a bug related to the OS distribution on MySQL. What server OS is used?

jelo wrote: What is the build of LS 2.05+ ?

What's the best way to determine that?

It could be a bug related to the OS distribution on MySQL. What server OS is used?

RHEL 6.8

Turns out we have some widespread replication issues. This had nothing to do with limesurvey, but it did help uncover the problem.

Thanks.