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Posted by d on 09/27/07 11:37
"Chung Leong" <chernyshevsky@hotmail.com> wrote in message
news:1137286681.506700.37070@g43g2000cwa.googlegroups.com...
> gooze wrote:
>> Hello
>>
>> I am working on an applicaion that shows several pictures on a webpage.
>> These pictures are saved in a MySQL DB as BLOB. I noticed, that the web
>> server suffers in its performance by printing the pictures. Let's say
>> there are 20 pictures to show, there also are 20 queries to do. This is
>> the way I am doing it up to now:
>>
>> index.php
>> <?php
>> foreach ($icons as $value) {
>> echo '<img src="./show_icon.php?icon_id=' . $value . '">';
>> }
>> ?>
>>
>> show_icon.php
>> <?php
>> $query = "SELECT icon FROM pictures WHERE id='$_GET['icon_id'] ";
>> $result = @mysql_query ($query) or die (mysql_error());
>> $icon = @mysql_result ($result, 0, "icon");
>>
>> header("Content-type: image/png");
>> echo $icon;
>> ?>
>>
>> Actually this works quite well, but the performance is an issue. Is
>> there a more simple or more elegant way than the code above? Is there
>> actually a solution to do it with one query instead of 20 queries?
>>
>> Thanks for your help
>> Stefan
>
> The performance issue you're experiencing is unlikely to be caused by
> the overhead of storing images in the database. The bottleneck is
> usually the Internet. Even a slow server can retrieve data from the
> database faster than can be transferred across the network.
>
> There are a couple things that could slow things down. First, make sure
> the images are cached on the client-side by sending the appropriate
> HTTP headers. Second, check to see if session-auto-start is turn on. If
> it is, then call session_write_close() before sending the image data.
Remember that reading images from a database requires the whole image to be
passed around from DB server to php, then php out to the web server, to the
client. That is a significant hit on a site with only a reasonable amount
of traffic.
That session_write_close() tip is a good one, though - more than two scripts
using the same session will cause the third to time out, which is quite
unexpected to most people :)
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