Pre-judgment and Incomplete Allocation Approach for Query Result Cache

Query result caching is a crucial technique employed in search engines, reducing the response time and load of the search engines. As search engines continuously update their indexes, the query results in long-lived cache entries may become stale. It is important to provide the refresh mechanism to enhance the degree of freshness of cached results. We present a pre-judgment approach to improve the freshness of the result cache and design an incomplete allocation algorithm. We introduce the query-Time-to-live (TTL) and term-TTL structure to pre-judge the result cache. The query-TTL is used to pre-check the likelihood of a cache hit and term-TTL is applied to maintain all terms of the latest posting list. For the cache structure, we design a Queue-Hash structure and develop the corresponding incomplete allocation algorithm. The preliminary results demonstrate that our approaches can improve the freshness of cached results and decrease processing overhead compared with no pre-judgment approaches.