Thank you for your very prompt reply.
I stopped the query, and the update process stopped, with the messages
ERROR 2013 (HY000) at line 15: Lost connection to MySQL server during query
ERROR 2006 (HY000) at line 16: MySQL server has gone away
ERROR 2006 (HY000) at line 17: MySQL server has gone away
ERROR 2006 (HY000) at line 18: MySQL server has gone away
ERROR 2006 (HY000) at line 19: MySQL server has gone away
ERROR 2006 (HY000) at line 20: MySQL server has gone away …
I just restarted the update process for want of anything else to do
The server is once again working on the statement:
server_time DATETIME NOT NULL
I should point at that the mysql server state is "Repair with keycache "
This is a dev environment, so no-one is using the site, but I added these lines to the config file, just in case.
maintenance_mode = 1
record_statistics = 0
The other site I updated was on the same server, but the database had less piwik data.
I am worried that if I just kill the alter table statement, then the database table would not be updated correctly anyway?
Has no-one else experienced this issue?