Cache for Pictures from database

[bengreen]

Hi,
I store images of users in a database, and then generate a profile of the users from the database.
When i refer to the picture i have a file picture.php that pulls the image from the database and sends it as jpeg to the browser.

My problem is that the browser insists on getting a new copy of the picture every time it is viewed, instead of using a cache of it.

What is it that is going wrong, and how can i fix it.

regards
Ben

[[deleted]]

Most browsers are setup not to cache dynamically created pages because they can change at any time.

Another reason not to use images in a database.

You'll have to change your image script so taht it sends different cache headers, search the forum for more info.

[mithril]

Another option is to use the filesystem for what it's for, storing files🙂

Just change the database so that it stores the path and filename of the image in question. Then pass that string into the <img src>. This has a good chance of solving your caching issue without the need of sending custom cache headers.

-geoff

[marwood3]

There are sometimes reasons for storing images in a database, although I would agree that the filesystem is a better place for them

[Anon]

Try adding an expires header sometime in the future, something like:

header("Expires: Tue, 01 Jan 2002 00:00:00 GMT");

before you send anything to the browser for your image.

-t

[djgibbon]

You'll want to be passing headers before your image data. This is what I use before dynamically generated images, and it seems to do the trick:

header ("Expires: Mon, 26 Jul 2002 05:00:00 GMT"); // Date in the future
header ("Cache-Control: public"); // HTTP/1.1
header ("Pragma: cache"); // HTTP/1.0

HTH

P

[Anon]

Where can I find a list of pros and cons for storing picsas blobs in a database. I am against it, but my boss wants it done unless I can show good proof of the drawbacks. Any help would be appreciated.

Thanks,

Jim

[Anon]

Justification for storing images in the database is fairly application specific.

There is no "one size fits all" answer I'm afraid.

Why does your boss want you to store them in the database in the first place, and is it worth fighting with the boss over?

-t

[[deleted]]

"and is it worth fighting with the boss over?"

The boss is usually wrong. 🙂

[mithril]

Well, like Tim said, there's no one definitive list of pros and cons. However, some that I can think of off the top of my head are:

Pros:

• better security. Since the images must be retrieved by a db call, people can't scam your images by directory browsing.

• if you're writing for a distributed setup (ex. mulitple engineers in different locations revising the same AutoCAD doc and needing to have an easy way to rollback to previous versions), storing all revisions in the db is often much easier than trying to manage ftp file uploads by people who may or may not know what they're doing. For example, you can specify and maintain a standardized naming scheme. This point also relates to the security issue, for example the folks at Boeing might not want Lougheed engineers to have easy access to the blueprints of the new planes under currently under development🙂

Cons:

• it's much slower to store images in a db. The code needed to retrieve, format, and display the image is much more intensive than a simple filesystem call by the <img> tag. HTML executes much faster than any scripting language, thus you should try to use straight HTML whenever possible

• related to the above, it's much more expensive in terms of programming time due to the larger amount of code needed to display the images

• if your db goes down, or your script breaks, all the images are no longer available. Of course, if either of those things happen you're probably going to have bigger worries than a couple images not displaying🙂

Hope this gives you something to go on in case you decide to go head to head with the higher ups.

-geoff

[Anon]

Appreciate the help and comments. Actually, I am pretty lucky in that my boss actually listens to my opinion and we discuss the best way to go. After discussing the problem with possible slow down caused by using the database to store the pics, plus the dbase dying and killing all the pics was enough to convince all that it isn't the way to go in our situation.

Thanks for the info, appreciate it.

Jim

[bengreen]

Hi Phil,
I eventually got around to trying your code for the caching of images off the database.
It works a treat,
Thank you

regards
Ben