Product Documentation

FairCom ISAM for C

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Disabling File Cache

In some cases, it might be beneficial to define that a certain file NOT be cached.

For example, if a file contains very large variable-length records (BLOBS), it might be more efficient to bypass the cache and rely solely on the operating system's cache support. The FairCom Server does not store the full variable-length record in cache, but retains the first and last page of the variable-length record. This prevents large blocks of data from consuming the cache and also alleviates the management of a large number of cache pages for any one particular record.

To disable cache for a given file, use the following server configuration keyword:

NO_CACHE <data file name>

Note: <data file name> may include a wildcard pattern using ‘?’ for a single character and ‘*’ for zero or more characters. The Server Administrator can specify multiple NO_CACHE configuration entries.

Caching can only be turned off for entire superfiles (i.e., the superfile host), not for individual superfile members. Index files require the use of index cache pages and must be cached.