Admission Policies for Caches of Search Engine Results

  • Ricardo Baeza-Yate
  • Flavio Junqueira
  • Vassilis Plachouras
  • Hans Friedrich Witschel
Part of the Lecture Notes in Computer Science book series (LNCS, volume 4726)


This paper studies the impact of the tail of the query distribution on caches of Web search engines, and proposes a technique for achieving higher hit ratios compared to traditional heuristics such as LRU. The main problem we solve is the one of identifying infrequent queries, which cause a reduction on hit ratio because caching them often does not lead to hits. To mitigate this problem, we introduce a cache management policy that employs an admission policy to prevent infrequent queries from taking space of more frequent queries in the cache. The admission policy uses either stateless features, which depend only on the query, or stateful features based on usage information. The proposed management policy is more general than existing policies for caching of search engine results, and it is fully dynamic. The evaluation results on two different query logs show that our policy achieves higher hit ratios when compared to previously proposed cache management policies.


Cache Size Admission Policy Frequent Query Admission Control Policy Search Engine Result 


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Copyright information

© Springer-Verlag Berlin Heidelberg 2007

Authors and Affiliations

  • Ricardo Baeza-Yate
    • 1
  • Flavio Junqueira
    • 1
  • Vassilis Plachouras
    • 1
  • Hans Friedrich Witschel
    • 2
  1. 1.Yahoo! Research, BarcelonaSpain
  2. 2.University of LeipzigGermany

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