In the past two days, I've seen two references to Practical PHP Programming, an
online book that serves both as an introduction to programming with PHP5 and
MySQL as well as a good advanced reference with many good tips.
This evening, I was browsing through the Performance chapter (chapter 18),
and found a number of cool things, both for PHP and MySQL. Many were common
sense things that I've been doing for awhile, but which I've also seen and
shaken my head at in code I've seen from others (calculating loop
invariables at every iteration, not using variables passed to a function,
not returning a value from a function, not using a return value from a
function). Others were new and gave me pause for thought (string
concatenation with the '.' operator is expensive, especially when done more
than once in an operation; echo can take a comma separated list).
Some PHP myths were also dispelled, some of which I've been wondering about
for awhile. For instance, the amount of comments and whitespace in PHP are
not a factor in performance (and PHP caching systems will often strip them
out anyways); double quotes are not more expensive than single quotes unless
variable interpolation occurs.
It also has some good advice for SQL optimization, and, more importantly,
MySQL server optimization. For instance, the author suggests
running 'OPTIMIZE TABLE table;' on any table that has been
added/updated/deleted from to any large extent since creation; this will
defrag the table and give it better performance. Use CHAR() versus
VARCHAR(); VARCHAR() saves on space, but MySQL has to calculate how much
space was used each time it queries in order to determine where the next
field or record starts. However, if you have any variable length fields, you
may as well use as many as you need -- or split off variable length fields
(such as a TEXT() field) into a different table in order to speed up
searching. When performing JOINs, compare on numeric fields instead of
character fields, and always JOIN on rows that are indexed.
I haven't read the entire book, but glancing through the TOC, there are some
potential downfalls to its content:
- It doesn't cover PhpDoc
- It doesn't appear to cover unit testing
- Limited coverage of templating solutions (though they are mentioned)
- Limited usage of PEAR. The author does mention PEAR a number of times,
and often indicates that use of certain PEAR modules is preferable to using
the corresponding low-level PHP calls (e.g., Mail and Mail_MIME, DB), but in
the examples rarely uses them.
- PHP-HTML-PHP... The examples I browsed all created self-contained
scripts that did all HTML output. While I can appreciate this to a degree,
I'd still like to see a book that shows OOP development in PHP and which
creates re-usable web components in doing so. For instance, instead of
creating a message board script, create a message board
class that can be called from anywhere with metadata specifying the
database and templates to use.
All told, there's plenty of meat in this book -- I wish it were in dead tree
format already so I could browse through it at my leisure, instead of in
front of the computer.
