Re: Difference between storing files on folder and in mysql db
- From: Jerry Stuckle <jstucklex@xxxxxxxxxxxxx>
- Date: Wed, 09 Jan 2008 15:39:15 -0500
NC wrote:
On Jan 8, 8:05 pm, Jerry Stuckle <jstuck...@xxxxxxxxxxxxx> wrote:NC wrote:
The only significant difference is the DB server load. Since <imgNot true. <img> tags are handled identically by the client, whether the
data="*"> tags are not (yet?) commonly supported by browsers, you need
a separate instance of an image display script (and a separate
connection to the DB server) to display each image. So if your Web
page has 100 images on it, it will require 101 nearly simultaneous
connections to display itself and the images, as opposed to one
connection if images were stored in the file system. Granted, image
retrieval connections would be very short, but at high loads, this
architecture would be patently inferior to disk-based alternative.
image comes from the database or the file system. The client doesn't
know or care if the image is from a database or not.
The client doesn't indeed, but the DB server does. Let's say we have
a script img.php (error handling omitted for brevity):
$id = (int) $_GET['id'];
mysql_connect('server', 'user', 'password');
mysql_select_db('images');
$result = mysql_query("SELECT imageData FROM images WHERE id = $id");
$record = mysql_fetch_row($result);
header('Content-type: image/jpeg');
echo record[0];
Let's further say that there is a script index.php that includes this
fragment:
for ($i = 1; $i <= 100; $i++) {
echo "<img src='img.php?id=$i'>";
}
So when index.php runs, it outputs 100 <img src='img.php?id=*'> tags,
so 100 instances of img.php are also run and each makes a connection
to the DB server.
Please feel free to point out any errors in the above argument.
No errors at all. But if it's serving from the file system, then the server has to make the connection to the file system, also. Sure, it is less handling. But it's not that significant in most site.
Additionally, how many sites do you know which serve 100 images in a single page? Not many - the load time would be so slow it wouldn't be funny.
Also, if you use MyISAM tables, storing large images in them willFew Linux implementations have a 2GB limit any more. Most are at least
bring you to the limit of table file size much more quickly. If your
average image is 1 MB and your file system's maximum file size is 2 GB
(there are still some older Linux servers whose file systems have this
constraint), you will only be able to store about 2,000 images until
your table exceeds the maximum allowed file size.
4GB, and some implementations are much larger.
Yes, but it's an issue the OP needs to check on before commencing
development.
Yes, and they need to ensure they aren't running under MS DOS, with it's 640K limit, also :-)
Seriously - if they're running that old of a kernel, it's time to upgrade anyway.
Also, the typical image size is *much smaller* than 1MB.
Depends on where you are and what you do. The OP mentioned an "image
competition", which could be en event where average image size is much
LARGER than 1 MB. A digital photo shot by a professional (or even top-
of-the line amateur) camera can easily be 10 MB, so can a piece of
digital artwork or a magazine page layout.
Sure, but they typically aren't uploaded to the server at that size, and if they are, I hope the developer will trim them down to size. Load time for 10MB files would be terrible, especially on DSL.
An over-generalization. Many have images stored in the database itself.Our company is starting an image-competition soon, and I am not sureLarge image sharing sites invariably stick to the second approach.
if I should write the php script to insert the binary code into a
mySQL database or if I should just store the files in a dedicated
folder and the data about them in the mySQL database.
Moreover, images may be stored on separate servers, optimized for
serving static content.
Please name one. I, meanwhile, will follow my own advice and do the
same. In his book, "Building Scalable Web Sites", Cal Henderson,
chief software architect of Flickr, describes Flickr's image storage
facility (p.152): disk-based and redundant, with synchronous writes to
primary storage and asynchronous writes to multiple backup storage
locations.
Cheers,
NC
Sure, that's one way. But it's not the only way.
IBM's document management system (don't know what it's called nowadays) has been doing it since the mid 80's, at least. I do it on some of my sites. And I've seen other people do it.
You don't see it as much on the web because too many people who have never tried it claim it's a bad way to do things.
In fact, a database can often be the better way to go. It can, for instance, handle 100K images in one table quite easily. There aren't many file systems which can handle that many images in a single directory.
--
==================
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Jerry Stuckle
JDS Computer Training Corp.
jstucklex@xxxxxxxxxxxxx
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