EVOLUTION-MANAGER

Edit File: fieldcaches.txt

============ Field caches ============ The default (``filedb``) backend uses *field caches* in certain circumstances. The field cache basically pre-computes the order of documents in the index to speed up sorting and faceting. Generating field caches can take time the first time you sort/facet on a large index. The field cache is kept in memory (and by default written to disk when it is generated) so subsequent sorted/faceted searches should be faster. The default caching policy never expires field caches, so reused searchers and/or sorting a lot of different fields could use up quite a bit of memory with large indexes. Customizing cache behaviour =========================== (The following API examples refer to the default ``filedb`` backend.) *By default*, Whoosh saves field caches to disk. To prevent a reader or searcher from writing out field caches, do this before you start using it:: searcher.set_caching_policy(save=False) By default, if caches are written to disk they are saved in the index directory. To tell a reader or searcher to save cache files to a different location, create a storage object and pass it to the ``storage`` keyword argument:: from whoosh.filedb.filestore import FileStorage mystorage = FileStorage("path/to/cachedir") reader.set_caching_policy(storage=mystorage) Creating a custom caching policy ================================ Expert users who want to implement a custom caching policy (for example, to add cache expiration) should subclass :class:`whoosh.filedb.fieldcache.FieldCachingPolicy`. Then you can pass an instance of your policy object to the ``set_caching_policy`` method:: searcher.set_caching_policy(MyPolicy())