Memory table truncating automatically

[PHP Monkey]

Hello, I have a memory table that has 6 fields, 3 indexes and about 650,000 rows. It loads into memory fine, and works well when my application runs select quieries on it. The problem is that the table likes truncating itself. I had loaded it yesterday, ran my application, went to sleep and today morning I find it truncated. The server has not been rebooted. What can be the possible reasons why this would happen?

Couple of things to know:

I do have a dedicated server but there are other developers using the machine (so it could be a possiblity that they use up memory or something?)
The machine has enough memory to load the table

My question pretty much boils down to this:

If the machine runs out of memory, does it truncate the table?

Thanks everyone.

[longneck]

have you looked at the uptime of the mysql service? not the uptime of the OS, but the uptime of the mysql service.

[PHP Monkey]

Hey, thanks for your reply. Got back from the server admin. Yes MySQL has been restarted by another developer. This would cause it to truncate right?

[longneck]

yup.

but if your server has enough memory to hold the table, you can probably get nearly the same performance by configuring your table cache properly and letting mysql handle keeping the need rows in memory for you.

[PHP Monkey]

Caching would only happen once a row is called correct?

[longneck]

yes.