creating thumbnails from images...

[Anon]

Hello all!

I'm trying to figure out how I can automatically create thumbnail images from images that I've stored in mysql. All of the examples that I've seen that automatically create thumbnail images require the image to be stored in a directory. Can somebody help me out with this?

-- tale

[[deleted]]

All the examples use files because it's not smart to store images in the database.
ie: take your images out of the database.

[Anon]

That's not right. Since v3.23.23 of MySQL you can index BLOB columns and since filesystems have to use hash functions,MySQL can indeed be faster than a normal file system.

[[deleted]]

You can index BLOB columns.
Care to tell me how that helps when you are looking for filenames?

It's very difficult to be faster than the filesystem, especially for MySQL and Binary data.

Why?
Because MySQL is an extra layer between PHP and the filsystem.
PHP uses cooked files, so it still depends on the filesystem to give it it's data.

That means your blob data is read by the filesystem, sent to MySQL, who then sends it on to PHP.

If you access the filesystem directly, you still get the same data, but you don't waste resources passing it through MySQL first.

[Anon]

Hello all!

I appreciate all of the discussion about whether to store my images in the database or file system. I originally made the decision to store the images in the db because I'm looking to store about 500,000+ images. From my research, Linux doesn't have hashing or indexing built into the filesystem (ext2 or rfs). And in addition to Linux doing a linear search on the files to find them, there would be the problem of backing up the images and the database with the site still up and running. The idea of having to somehow keep the pictures and database data in sync really scares me! :-) So that's why I decided to use the db to store the images.

Now, does anybody have any answers to my original post? I still don't have a clue how to generate image thumbnails from images stored in a database.

-- tale

[[deleted]]

You'll have to write the file to disk before you can open it with the GD tools or any other tool.

Just trying to explain why putting images in a database is not a good idea.

MySQL is no PgSQL or Informix.

1.
500k+ images of 20k each give you a database of 500000*20k = 10Gbyte.
As MySQL uses cooked files, you'll need a 10GByte file.
Most filesystems don't allow files larger than 2GB.

2.
If you want to stay 'live' during a backup, you can only backup into SQL statements, which means you have to SELECT just about all your data from the tables to back them up. I don't think 500k+ consecutive SELECT's is going to perform well on a 10GByte table :-)
(Let alone that the entire backup can be held up if you do a slow insert. and I don't think there'll be many fast inserts on a 10Gbyte file)

If I were you I'd most definately store the files in the filesystem.
You can store the location of the file in the database, and let PHP create subdirectories as required. Squid uses the same type of system, creating 16-256 directories with 16-256 subdirectories each.
That gives you a huge space to store the files in.
You won't lose track of which files you have because you'll write a PHP routine to handle all that.

[Anon]

This is from the last post:

You can store the location of the file in the database, and let PHP create subdirectories as required. Squid uses the same type of system, creating 16-256 directories with 16-256 subdirectories each.
That gives you a huge space to store the files in.

Can you tell me more about what Squid is and how it knows how many directories to create?

-- tale

[[deleted]]

Sorry, should have mentioned that.

Squid is a proxy-deamon for unx.
It stores all web objects on disk (pages, images, sounds etc)
Thus it needs a huge storage space.
How many directories to create is simply read from a configuration file.
But you can calculate it quite easily.
If you want to store 256 files per dir, and you want to store 500k files,
youd need 500k/256 = 1954 dirs.
That's 8 main directories with each 256 subdirs with each 256 files.
8256*256=524288 files
If you need more files, just add one more main dir.

If you stick to 256 limits, you can get 256256256 =16777216 files in just two directory levels.