function cache_set

Stores data in the persistent cache.

The persistent cache is split up into several cache bins. In the default cache implementation, each cache bin corresponds to a database table by the same name. Other implementations might want to store several bins in data structures that get flushed together. While it is not a problem for most cache bins if the entries in them are flushed before their expire time, some might break functionality or are extremely expensive to recalculate. The other bins are expired automatically by core. Contributed modules can add additional bins and get them expired automatically by implementing hook_flush_caches().

The reasons for having several bins are as follows:

  • Smaller bins mean smaller database tables and allow for faster selects and inserts.
  • We try to put fast changing cache items and rather static ones into different bins. The effect is that only the fast changing bins will need a lot of writes to disk. The more static bins will also be better cacheable with MySQL's query cache.


$cid: The cache ID of the data to store.

$data: The data to store in the cache. Complex data types will be automatically serialized before insertion. Strings will be stored as plain text and are not serialized. Some storage engines only allow objects up to a maximum of 1MB in size to be stored by default. When caching large arrays or similar, take care to ensure $data does not exceed this size.

$bin: (optional) The cache bin to store the data in. Valid core values are:

  • cache: (default) Generic cache storage bin (used for theme registry, locale date, list of simpletest tests, etc.).
  • cache_block: Stores the content of various blocks.
  • cache_bootstrap: Stores the class registry, the system list of modules, the list of which modules implement which hooks, and the Drupal variable list.
  • cache_field: Stores the field data belonging to a given object.
  • cache_filter: Stores filtered pieces of content.
  • cache_form: Stores multistep forms. Flushing this bin means that some forms displayed to users lose their state and the data already submitted to them. This bin should not be flushed before its expired time.
  • cache_menu: Stores the structure of visible navigation menus per page.
  • cache_page: Stores generated pages for anonymous users. It is flushed very often, whenever a page changes, at least for every node and comment submission. This is the only bin affected by the page cache setting on the administrator panel.
  • cache_path: Stores the system paths that have an alias.

$expire: (optional) Controls the maximum lifetime of this cache entry. Note that caches might be subject to clearing at any time, so this setting does not guarantee a minimum lifetime. With this in mind, the cache should not be used for data that must be kept during a cache clear, like sessions.

Use one of the following values:

  • CACHE_PERMANENT: Indicates that the item should never be removed unless explicitly told to using cache_clear_all() with a cache ID.
  • CACHE_TEMPORARY: Indicates that the item should be removed at the next general cache wipe.
  • A Unix timestamp: Indicates that the item should be kept at least until the given time, after which it behaves like CACHE_TEMPORARY.

See also



51 calls to cache_set()
archiver_get_info in includes/
Retrieves a list of all available archivers.
book_menu_subtree_data in modules/book/book.module
Gets the data representing a subtree of the book hierarchy.
CacheClearCase::testClearArray in modules/simpletest/tests/cache.test
Test clearing using an array.
CacheClearCase::testClearCid in modules/simpletest/tests/cache.test
Test clearing using a cid.
CacheClearCase::testClearWildcard in modules/simpletest/tests/cache.test
Test clearing using wildcard.

... See full list


includes/, line 141


function cache_set($cid, $data, $bin = 'cache', $expire = CACHE_PERMANENT) {
    return _cache_get_object($bin)->set($cid, $data, $expire);

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