On 4/3/06, tedd <tedd@xxxxxxxxxxxx> wrote: > chris said: > > >Time. Opening a db connection is time consuming. There are many levels > >involved (making the connection, authentication, etc).. Even worse if > >the connection is over tcp/ip because that overhead comes in on top as > >well. > > I replied: > > >Have you timed it? > > > >Maybe I'll do that tomorrow. > > Okay, I performed a test that made 100 queries, and found that it > took about four times as long to open a dB connection each time and > get the data as it did to open it once. In other words, if your > script pulls data from a dB 100 times, then making a connection to > the dB once, pulling the data, and then closing the dB is four times > as fast as opening the dB, pulling the data, and closing the dB in > sequence one hundred times. > > Now, that sounds like you should open your dB at the start of your > script and just leave it open until the your script quits (as the > original poster suggested), but there's a few thing to consider here. > > 1. The total time difference shown in the above test is a little over > a tenth of a second. > > 2. By keeping the dB open, you're actually tying up the resources of > the server more than necessary. After all, your script will always > run longer than the query, right? > > 3. Most scripts (I'm guess here) don't access the dB 100 times or > more -- so doing is less, means less of a difference. > > 4. And lastly, by closing the dB in your script when you're done with > it, allows the server to use it's resources to "clean-up" quicker and > have more time to be responsive to other queries. > > So, not that you implied otherwise, I still don't see any convincing > argument as to why one should open a dB at the start of a script and > not close it as the original poster asked. Furthermore, not that I'm > anyone special, but if I was overlooking someone's code who did that, > I wouldn't think favorably of the technique -- it would appear as > sloppy programming to me. Just out of interest, could you re-run the test using persistent connections? change mysql_connect to mysql_pconnect.. -- Postgresql & php tutorials http://www.designmagick.com/ -- PHP General Mailing List (http://www.php.net/) To unsubscribe, visit: http://www.php.net/unsub.php
