January 28th, 2004
Lessons
Some random lessons I've learned when scripting in PHP.
Constants are the bomb. I've been using the define() function in PHP to define session variables across the board; no more need to define "global" variables or use some ugly hack with (real) global variables.
Originally I thought the limitation of the constants were that they couldn't store anything other than strings and variables; they couldn't store hashes.
But I found out that if you use the serialize() function in PHP, you can convert a hash to a string (of sorts). So then simply store this as a constant, then unserialize() it when you need to grab the data.
A real application of this has been for the generation of lists. For example, let's use the TokkiProject website (the hyori gallery is a good example).
Right now, on each page's generation, the script hits the database many times to grab the imageids for a given albumid. Let me give you a graphical view of the database in question:
---------------------------------------
| IMAGEID | ALBUMID |
----------------------------------------
| 2 | 1 |
| 4 | 1 |
| 234 | 1 |
----------------------------------------
So for each page generation in Tokki currently, the database gets hit three times so I can generate the "next image," "previous image", and the page navigation on the bottom.
This is bad practice. The albums aren't updated that often; ideally the "total" imageid listing should be stored somewhere more static. With a large gallery like hyori, I would imagine the database gets hit about 1500 times PER page generation.
So if we were to create a hash of the imageids (call it TOTIMAGEID) and store it someplace (memory? flat file? db? it's irrelevant) with a timestamp ... upon every page view, we could bring up the timestamps of the last updated time for the album and the timestamp for the TOTIMAGEID) and do a quick comparison. If the album has been updated, *then* hit the database and update the imageids. Otherwise, just use the exiting TOTIMAGEID.
With serialize(), it's really easy to just take that hash and store is a string somewhere. Wooooooooooo.
Constants are the bomb. I've been using the define() function in PHP to define session variables across the board; no more need to define "global" variables or use some ugly hack with (real) global variables.
Originally I thought the limitation of the constants were that they couldn't store anything other than strings and variables; they couldn't store hashes.
But I found out that if you use the serialize() function in PHP, you can convert a hash to a string (of sorts). So then simply store this as a constant, then unserialize() it when you need to grab the data.
A real application of this has been for the generation of lists. For example, let's use the TokkiProject website (the hyori gallery is a good example).
Right now, on each page's generation, the script hits the database many times to grab the imageids for a given albumid. Let me give you a graphical view of the database in question:
---------------------------------------
| IMAGEID | ALBUMID |
----------------------------------------
| 2 | 1 |
| 4 | 1 |
| 234 | 1 |
----------------------------------------
So for each page generation in Tokki currently, the database gets hit three times so I can generate the "next image," "previous image", and the page navigation on the bottom.
This is bad practice. The albums aren't updated that often; ideally the "total" imageid listing should be stored somewhere more static. With a large gallery like hyori, I would imagine the database gets hit about 1500 times PER page generation.
So if we were to create a hash of the imageids (call it TOTIMAGEID) and store it someplace (memory? flat file? db? it's irrelevant) with a timestamp ... upon every page view, we could bring up the timestamps of the last updated time for the album and the timestamp for the TOTIMAGEID) and do a quick comparison. If the album has been updated, *then* hit the database and update the imageids. Otherwise, just use the exiting TOTIMAGEID.
With serialize(), it's really easy to just take that hash and store is a string somewhere. Wooooooooooo.
