Milan Babuskov wrote:

> Lester Caine wrote:
>
>>Of cause in that situation you need to block activity on the database
>>until you have finished. My usual approach is just to 'close' the site
>>(switch to maintenance message) and restart Apache.
>
> I have many applications running and using different databases. While
> one db is updated, others should be able to keep running. I solved it
> by creating a dummy lock file. Each page in my web apps has a line:
>
> require_once('login.php');
>
> Which in turn uses file_exists() to check if lock file is there. If it
> is, it locks the users out until database is updated.

Actually the site closed is site specific - only need to restart Apache
if the links to THAT database do not drop. The rest of the sites just
carry on.

>>I would still maintain that structural changes should be made on a copy
>>of the data and that live data would be pumped in when you are happy,
>>but I'm not enforcing that rule as strongly as I used to :)
>
> And it's error prone with generators and all that stuff ;)

I don't have problems with generators, but been caught too many times
with data that screws a live update ;) You have to be able to get back
to a working system when an update fails, but as long as you backup
before starting ( and even when it's the first item on the to do list
the engineers STILL forget to ! )

--
Lester Caine - G8HFL
-----------------------------
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