Wiki applications are becoming increasingly important for knowledge sharing between large numbers of users. To prevent against vandalism and recover from destructive edits, wiki applications need to maintain the revision histories of all documents. Due to the large amounts of data and traffic, a Wiki application needs to store the data economically and retrieve documents efficiently. Current Wiki Data Management Systems (WDMS) make a trade-off between storage requirement and access time for

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... ment update and retrieval. We introduce a new data management system, Cosmos, to balance this trade-off. To compare Cosmos with the other WDMSs, we use a 68GB data sample from English Wikipedia. Our experiments show that Cosmos uses one-fifth of the disk space when compared to Medi-aWiki (Wikipedia's backend) and performs faster than other WDMSs at document retrieval.