JadeDbFilePartitions::getStatistics Method

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JadeDbFilePartitions::getStatistics Method

getStatistics(jdo: JadeDynamicObject input);

The JadeDbFilePartition class getStatistics method returns statistics relating to read and write operations on the persistent database file partition represented by the JadeDbFilePartition instance used as the method receiver.

The values are returned as Integer64 properties in the dynamic object specified by the jdo parameter. The calling process is responsible for creating and deleting the JadeDynamicObject instance.

The properties returned in the JadeDynamicObject are listed in the following table.

Property	Description
logicalReads	The total number of read requests
logicalWrites	The total number of write requests
logicalReadBytes	The total accumulated size for all read requests
logicalWriteBytes	The total accumulated size for all write requests
physicalReads	The actual number of file partition read operations
physicalWrites	The actual number of file partition write operations
physicalReadBytes	The actual accumulated size for all file partition read operations
physicalWriteBytes	The actual accumulated size for all file partition write operations

The logical counts record the number and size of requests that can be serviced in cache, whereas the physical counts record actual disk activity.

The returned values include cumulative counters, which are not reset during the lifetime of the database server node. You need to compare values from one execution of the getStatistics method with the previous values, to work out the differences.

The cumulative values are held as 64-bit unsigned integers, which are copied to the dynamic object as Integer64 values. The maximum value before they wrap around to negative values is therefore 2^63 - 1 (approximately 8 Exabytes).

For an example of this method, see the JadeDbFilePartition class getStatistics method in Volume 1 of the JADE Encyclopaedia of Classes.