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A method for faster searches of external file properties using negative caching of directory relationships Disclosure Number: IPCOM000014184D
Original Publication Date: 2001-Jan-01
Included in the Prior Art Database: 2003-Jun-19

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A method for faster searches of external file properties using negative caching of directory relationships Disclosed is a software method which improves performance on searches for auxiliary attributes attached to file system resources. It utilizes a negative cache based on directory relationships. When a search for auxiliary attributes results in a miss, additional checks are performed to determine if attributes exist for any peer files in the same directory. If not, then the directory can be cached as a directory which does not contain any objects with auxiliary attributes. On future requests, the negative cache is used to avoid exhaustive searches and quickly return a miss. The method works as follows. When a file resource is accessed, its parent directory information is also retrieved. For example if /tmp/file is accessed, then identifying file information is obtained for both /tmp and file . This could be in the form of names or perhaps binary representations such as a file identifiers (fids), or inode number values. The database of auxiliary file attributes is organized in a manner such that every registered resource contains its parent directory association. In addition, the parent directory is used as a key for database searches. Using the parent directory association, resources with the same parent are searched looking for a match on the accessed resource. If no entries are encountered for the resource's parent directory, then the directory contains no resources with auxiliary attributes. With this knowledge, a negative cache entry can be created for the directory. The negative cache entry indicates no resources in that directory contain auxiliary attributes. On subsequent resource accesses, the negative cache is consulted. A hit in the negative cache for the accessed resource's parent directory quickly indicates the resource has no auxiliary attributes and that a more expensive database search is not required. As a result, the processing of the file resource is completed with minimal processing. The below