1. Without prefix is not really solution since one could have installed multiple piwiks in one database.

2. When recreating records, do we know the original prefix? Which tool are you using for this? Or how do you change the prefix? Only in the config file?

1. What is the issue with this approach? It should still be doable, as the prefix affects only table name, not records inside. And during the archiving process you should have access to the right config file which defines the prefix of archive tables.

2. The original prefix is not important if you recreate records based on current archive tables. Selecting max(idarchive) should be really fast and there's no need to access previous record from the sequence table.

Why do we have to change prefix in some cases? Just to keep all our databases consistent (e.g. when we import existing database to Piwik Cloud). Would be nice to have a command/script to do the job. If there are issues with the sequence table, it may be really confising for the end users, as the archving process doesn't update the reports in this case.

1. True! Sounds like simplest solution

2. I'm still not sure what you mean by recreate records but 1) sounds like a good solution anyway :)

2. To not start with 0 when there's no record for a given archive table in piwik_sequence, but instead check the the corresponding table.

I got that, what I don't get is how you change the prefix and recreate records. Like how do you do that step by step? Just to understand it better... I presume you basically import the tables into a database and then do a rename on the table names and that's it?

Anyway, still thinking 1) is best solution so doesn't really matter. We can simply save it without the prefix and also update existing records in the sequence table

@tsteur yes, our sys-admins were not aware that something may break after changing tables prefix and updating config file. Now the procedure is to update also records in the sequence table (change prefix).

OK got it. We should remove it, maybe better for Piwik 3.0 to not break anything. If something goes wrong, there could be serious problems

So the solution would be:

• Don't use prefixes in prefix_sequence table.
• Migrate data in prefix_sequence and remove any prefix there.

Assigning to LTS backlog.