[rt-users] RAM

[Scott Courtney]

On Wednesday 28 March 2007 11:25, Firas Batal (QA/EMC) wrote:
> I have RT 3.2.1 running with MySQL 4.0.21.  I use MYSQL with RT, and I
> have just created a ticket that contains a .zip attachment with a size
> of 11MB.  I wonder if one could guide me through the following:  I know
> that MYSQL need lots of RAM to breathe properly.  But, where is the file
> kept? Is in stored in records in RAM or its stored on the hard drive
> with a pointer of the location of the file stored in RAM?  

The backing store for BLOB fields in MySQL is within the table space, which
translates physically to a file on the hard drive (but it's not "one file
per attachment", rather all the attachments go into the database table file).
The exact way in which they're stored depends on which MySQL engine your
table uses (InnoDB, MyISAM, etc.).

Depending on how Perl handles HTTP POST requests, and possibly depending on
whether you are running RT in CGI mode or with mod_perl, the uploaded file
*may* be temporarily RAM-resident during the upload process, before it is
committed to the database. I'm not a Perl wiz, so I'll defer to someone with
more expertise on that question.

By the way, there is a special MySQL engine (at least in MySQL 5...not sure
if it existed back at 4.0.x or not) that stores database records in RAM for
very fast -- but volatile! -- temporary tables. That feature is used in
very specialized situations, and isn't normally relevant for RT. I mention it
here for completeness only. You are almost certainly NOT using this, because
anything in RAM vanishes if the system is rebooted.

Hope this helps.

Scott

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