org.apache.lucene.search

Interface QueryCachingPolicy

All Known Implementing Classes:

UsageTrackingQueryCachingPolicy

public interface QueryCachingPolicy

A policy defining which filters should be cached. Implementations of this class must be thread-safe.

See Also:

UsageTrackingQueryCachingPolicy, LRUQueryCache

WARNING: This API is experimental and might change in incompatible ways in the next release.

Field Summary

Fields

Modifier and Type	Field and Description
static QueryCachingPolicy	ALWAYS_CACHE Deprecated. This policy is inefficient as caching too aggressively disables the ability to skip non-interesting documents. See UsageTrackingQueryCachingPolicy.

Method Summary

Modifier and Type	Method and Description
void	onUse(Query query) Callback that is called every time that a cached filter is used.
boolean	shouldCache(Query query) Whether the given Query is worth caching.

Field Detail

ALWAYS_CACHE

@Deprecated
static final QueryCachingPolicy ALWAYS_CACHE

Deprecated. This policy is inefficient as caching too aggressively disables the ability to skip non-interesting documents. See UsageTrackingQueryCachingPolicy.

A simple policy that caches all the provided filters on all segments.

Method Detail

onUse

void onUse(Query query)

Callback that is called every time that a cached filter is used. This is typically useful if the policy wants to track usage statistics in order to make decisions.

shouldCache

boolean shouldCache(Query query)
             throws IOException

Whether the given Query is worth caching. This method will be called by the QueryCache to know whether to cache. It will first attempt to load a DocIdSet from the cache. If it is not cached yet and this method returns true then a cache entry will be generated. Otherwise an uncached scorer will be returned.

Throws:

IOException