August 1, 2014

Integers in PHP, running with scissors, and portability

Until recently I thought that currently popular scripting languages, which mostly evolved over last 10 years or something, must allow for easier portability across different platforms compared to ye good olde C/C++. After all, their development started a few decades after C, so its notorious caveats are all well-known and should be easy to avoid […]

PHP Sessions – Files vs Database Based

One may think changing PHP session handler from file based to database driven is fully transparent. In many cases it is, sometimes however it may cause some unexpected problems as happened to one of our customers. If you use file based sessions PHP will lock session file for whole script execution duration, which means all […]

Content delivery system design mistakes

This week I helped dealing with performance problems (part MySQL related and part related to LAMP in general) of system which does quite a bit of content delivery, serving file downloads and images – something a lot of web sites need to do these days. There were quite a bit of mistakes in design for […]

Debugging sleeping connections with MySQL

Have you ever seen connection in the SHOW PROCESSLIST output which is in “Sleep” state for a long time and you have no idea why this would happen ? I see if frequently with web applications and it is often indication of trouble. Not only it means you may run out of MySQL connections quicker […]

Why do you need many apache children ?

I already wrote kind of about same topic a while ago and now interesting real life case makes me to write again Most Web applications we’re working with have single tier web architecture, meaning there is just single set of apache servers server requests and nothing else – no dedicated server for static content, no […]

Are PHP persistent connections evil ?

As you probably know PHP “mysql” extension supported persistent connections but they were disabled in new “mysqli” extension, which is probably one of the reasons some people delay migration to this extension. The reason behind using persistent connections is of course reducing number of connects which are rather expensive, even though they are much faster […]

Wishes for new “Pure PHP” MySQL driver

If you’re following MySQL or PHP landscape you should have seen announcement by MySQL to develop pure PHP driver. If not – Here is FAQ . I’m to meet the team (Georg, Andrey etc) which will be developing this driver during my visit to Open Source Database Conference in November so I thought it would […]

Should MySQL and Web Server share the same box ?

This is interesting question which I thought it would be good to write about. There are obviously benefits and drawbacks for each of methods. Smaller applications usually start with single server which has both MySQL and Web server on it. In this case it is not usually the question but once application growths larger and […]

APC or Memcached

A while back I did Cache Performance Comparison for LAMP Stack. Looking at this data you can see memcached is about 5 times as slow as APC, and this is with tests done on localhost – with network difference is going to be larger, even with fastest network. Such latency can add up especially if […]

Database problems in MySQL/PHP Applications

Article about database design problems is being discussed by Kristian. Both article itself and responce cause mixed feellings so I decided it is worth commenting: 1. Using mysql_* functions directly This is probably bad but I do not like solutions proposed by original article ether. PEAR is slow as well as other complex conectors. I […]