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FairCom RTG has the ability to "prefetch" records to improve efficiency. When a client requests a record from the server, it can be more efficient to fetch several records at a time because they can share the same communications overhead. If the client needs another record, it may find that record has already been prefetched, making it available with no additional overhead.
In some situations, the prefetched records have been waiting long enough that they are no longer valid. This is particularly true if the application has been waiting for user input and other users have attempted to access the same records. In this case, it is necessary to invalidate the prefectched records so they will be fetched again when needed.
This modification introduces a new <prefetch ttl> attribute (ttl is "time-to-live") that defines the number of seconds a set of prefetched records remains valid. By default, the value is set to 0 seconds which means that prefetched records do not expire. When <prefetch> is enabled and <prefetch ttl> attribute is set, the records prefetched by a sequential read that are not consumed within the number of seconds specified in the <prefetch ttl> attribute will be discarded and the next consecutive sequential operation will cause a new prefetch to be requested from the server.
Example:
The following example enables <prefetch> reading for at least 5 records allowing 2 seconds to consume the prefetched records:
<config>
<instance server="FAIRCOMS">
<file>
<prefetch records="5" ttl="2"/>
</file>
</instance>
</config>
