I went through this process about 18 months ago (from 4.1 to 5.1). The upgrade itself went smoothly and only took a few hours, but some older code began breaking in various places afterwards.
The two broad issues that I encountered were: 1. some data types become a bit stricter in terms of what they will accept as default values. For example, TEXT fields no longer accepted NOT NULL, while DATE fields no longer accepted empty, zero or NULL values. IIRC, in MySQL 5 you can define how strictly you want some of these things to be enforced, but I figured it was for the best that I should get as much of this sort of thing into order as I could anyway. 2. the stricter nature of MySQL's LEFT JOIN syntax meant a few queries around the place began failing. The solution in most of my cases was to adjust the queries so that the table being referenced in the JOIN was the last in the FROM sequence immediately preceding the JOIN. These issues may not apply to you, or maybe there will be more, depending on how old/lazily written some aspects of your existing code base are. Obviously you'll want to resolve as many of these sorts of things as you can in a development environment first, so give yourself the time to make sure all is in readiness before going ahead for real. And as Cliff said, backup backup backup! :) Good luck. Brendan -----Original Message----- From: [email protected] [mailto:[email protected]] On Behalf Of Brendan Brink Sent: Thursday, 22 July 2010 12:00 p.m. To: [email protected] Subject: [phpug] convert mysql4 to mysql5 database hi there, has anyone had any experience in converting a mysql4 to a mysql5 database or has any words of advice / warnings? cheers brendan. -- NZ PHP Users Group: http://groups.google.com/group/nzphpug To post, send email to [email protected] To unsubscribe, send email to [email protected] -- NZ PHP Users Group: http://groups.google.com/group/nzphpug To post, send email to [email protected] To unsubscribe, send email to [email protected]
