I'm looking at upgrading my Percona Server setup from 5.5 to 5.6. Reading the upgrade docs from MySQL sounds mostly straightforward except for anything involving time/date columns.

As far as I can see, the (very confusing) docs say you'll have to break out your hex editor and hack the .frm files manually, and switch tables to use the memory storage engine temporarily (what if tables are bigger than memory?)! It goes on and on about how the timestamp, datetime and time columns are not compatible with older versions. As far as I can see from the field definitions, they are backward compatible by default, but have different storage requirements in their implementations, and they have added a new option to specify fractional parts of varying resolution. Of course, when upgrading you will not be using these new formats because they are not available in 5.5.

They make many references to versions prior to 5.6.4 - but I'm not clear whether this applies only to those upgrading from 5.6.[123], or includes anything from 5.*.

The Percona upgrade docs provide a pointer to the same upgrade instructions, but seem to make out that it's a simple binary upgrade and a run of mysql_upgrade, with no mention of this issue.

Am I being concerned about nothing?

  • I'm working on a more authoritative confirmation, but this looks like a case sloppy documentation, not cause for concern on a routine upgrade. It looks like it is all about directly importing a tablespace, not importing a table, the former being a low-level operation you are not going to be needing for a routine upgrade. – Michael - sqlbot Feb 24 '14 at 12:43

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