---json
{
    "canonical": ":page:cache",
    "name": "Page Cache",
    "page_id": "p46nws4v027jel84v4a9m"
}
---
====== How the page cache is working ?======



===== About =====
This page is talking about the cache management of a page.

A page is composed of:
  * its content 
  * and the [[docs:theme:slot:slot|slots]] of [[:docs:theme:template:template|its template]].

Each rendering goes into the cache until:
  * its content has changed
  * its [[docs:metadata:metadata|metadata]] has changed
  * any [[docs:app:configuration|app configuration]] has changed
  * a [[docs:cache:slot|cache dependency]] has occurred
  * the [[#expiration date|expiration date]] is due.




===== Expiration Date =====

You can set the expiration date of a page with two methods:
  * by page with the [[#expiration frequency]]
  * globally with the [[#cache time interval]] (maximum age)
==== Expiration Frequency ====

If you need to delete the page cache at interval because your page contains time-based data,
you can use the [[docs:cache:page_expiration_frequency|page cache expiration frequency]].

==== Cache time interval ====
The ''cache time'' interval is a standard dokuwiki [[docs:app:configuration|application configuration]] that sets a maximum age for the cache file.

If the interval has expired since the last creation date of the cache, the cache has expired and there is a cache miss.

You can read more on the [[doku>config:cachetime|Dokuwiki dedicated page]].


===== Purge Manually =====

By adding the ''purge'' property to a page URL, you will purge the cache for this particular page.

Example for this page: [[${path}?purge|${url}?purge]]

===== Monitoring =====

In the [[viewer|cache viewer]], you can see all cache hit or miss for the [[docs:theme:slot:slot|slots]].


For each slot, you can see the cache:
  * for the parsing instructions (the parse tree)
  * for the html page
  * for the [[docs:metadata:metadata|metadata]]

After 2 rendering, you should see only cache hits.
  * the first rendering will do the initial work
  * the second one should be only cache hit 


{{:docs:cache:combostrap_cache_hit.png|}}


<note>
If the second request does not hit the cache, this is because a metadata may have been set by a third party plugin.
</note>



===== Support and Configuration =====

==== useHeading ====
The [[doku>conf:useheading|useheading]] dokuwiki configuration has an impact on cache management, you should set disable it and set the value ''never''. More information on the [[support:useheading|dedicated page of this configuration]]