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Editorial Team
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Asked: 2026-05-14T23:18:58+00:00

What I’m doing I’m pulling an image from the database and sending it to

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What I’m doing

I’m pulling an image from the database and sending it to the browser with all the proper headers – the image displays fine. I also send an ETag header, using the SHA1 of the image’s content as the tag.

The images are getting called semi regularly, so caching is a bit of an issue (won’t kill the site, but nice to have).

The Problem

$_SERVER[‘HTTP_IF_NONE_MATCH’] is not available to me. As far as I can tell, this is because of PHP’s “disobey the cache controls” life style. I can’t mess with the session cache limiter, because I don’t have access. But, even if I did have access, I wouldn’t want to touch it: 99% of the site is under WordPress.

The Environment

  • PHP 4 (don’t ask)
  • Apache 2.2
  • WordPress
  • The images live in the database (largeblog), which I can’t change.

Any guidance, tip/tricks, etc. would be helpful. I don’t have much room to change the environmental/structural stuff.

Cheers.

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1 Answer

  1. Editorial Team

    Have you tried reading HTTP_IF_NONE_MATCH from apache_request_headers()?

    If you are running pre-4.3 php, it was called getallheaders() before.

    Edit
    I now see, in the page I linked, that you may also want to try to put

    RewriteEngine on
RewriteRule .* - [E=HTTP_IF_MODIFIED_SINCE:%{HTTP:If-Modified-Since}]
RewriteRule .* - [E=HTTP_IF_NONE_MATCH:%{HTTP:If-None-Match}]

    in the appropriate .htaccess file to force Apache to set the PHP $_SERVER[…] variables you’re unsuccessfully trying to read.

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