I work for a B2B company and on our website, we are having major cache issues. Whenever we do a substantial rollout of code, particularly when the "index.php" file is modified, the end users are continually having to "reload" in order to pick up the newest changes.
Here is what I have in place.
1) The following statements at top of PHP
A) header('P3P: CP="NOI ADM DEV PSAi COM NAV OUR OTRo STP IND DEM"');
B) header("Cache-Control: no-cache, must-revalidate"); // HTTP/1.1
2) All the JS / CSS links have versioning applied - <link "....file.js?vers=1"> with the "?vers=1" getting incremented.
What else can be done? I'm looking for advice on how to determine if PHP config cache or Apache cache is playing a role in this.
Any help would be greatly appreciated.