Hi, I would really appreciate replies on this one.
For the upcoming phpMyAdmin 4.1, we currently advertise the minimum MySQL version to 5 (meaning 5.0). However, MySQL 5.0 has reached "End of Product Lifecycle".
Moreover, we have a performance problem in phpMyAdmin 4.0 and 4.1, due to the navi panel mostly using INFORMATION_SCHEMA, which is poorly implemented in older MySQL versions. This performance problem is seen on servers with many (thousands?) of databases, which is not uncommon for host providers. We have bug tickets about this.
By the way, using INFORMATION_SCHEMA helps us for some features like the db filter (now with REGEX). I'm not sure how we could implement this efficiently with SHOW DATABASES.
I would like to increase the minimum MySQL version for phpMyAdmin 4.1. I got feedback from someone I trust, who is running MySQL 5.6 with thousands of real-world databases and did some tests; on this version, INFORMATION_SCHEMA performs ok.
If the team agrees, I would do some testing to find out at which point INFORMATION_SCHEMA's fetch problems were fixed. Then we would advertise this MySQL version as the minimum, and use only INFORMATION_SCHEMA in it (no more SHOW DATABASES).
I believe that this is a good service to do to the community; it resembles what we did when taking part in the GoPHP5 initiative.