Philip Thompson schreef:
Hi all.
Let me start out by saying, I have STFW and read through the list
archives. Now that that's out of the way.
To speed up our application, we want to implement using SESSIONs in some
locations. Beforehand, on every page, we would run approximately 30-40
queries just to get the page setup - user information and other stuff.
Now while we can't take away all of the setup queries, we would like to
reduce the startup number.
Ok, so I've implemented this in several places where information
basically does not change from page to page. Jumping to the
point/question... when does it become more inefficient to store lots of
information in SESSION variables than to run several more queries? Note,
we are actually storing sessions in the database - so a read/write is
required on each page load - it's not file sessions.
Now I know this can depend on the complexity of the queries and how much
data is actually stored inside the sessions... but initial thoughts? To
give you a number, the strlen of the _SESSION array is 325463 - which is
equivalent to the number of bytes (I think).
not exactly - depends on how you measure it, also the serialized form of the
session data is longer still because it contains data type descriptions et al.
are you running on a linux box? if so try using session files again and
sticking your session data in /dev/shm/some-dir which effectively means your
sticking the files in RAM ... generally much faster than using a DB or the FS,
on the other hand this is rather volatile (if the box goes down you lose all the
data ... but then you have other problems probably, you can get round it
by regularly backing up the contents of /dev/shm/some-dir and restoring the backup
if/when the machine reboots ... the backup can occur out of process, so
your page performance isn't directly effected, you'd still have to think about
file locking etc) I use this trick quite often, generally without bothering
to backup the session data (I figure if the site goes down completely then
losing session data is the least of my worries ... and a user won't be
all that surprised to find his login status wiped when the site comes back
up ... although he/she might be a little miffed)
Thanks,
~Philip
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