12.7 Setting the commit-time reflection processing

Commit-time reflection processing is a type of processing that involves writing the pages updated in a global buffer to disk whenever a COMMIT statement is issued.

Organization of this section
(1) Effects of commit-time reflection processing
(2) Specification
(3) Considerations

(1) Effects of commit-time reflection processing

The contents of the database are guaranteed upon completion of a transaction because the updated database contents are written to disk when the COMMIT statement is issued. Therefore, there is no need to recover the database from a synchronization point during full recovery processing, thereby reducing the time required for full recovery processing.

(2) Specification

Specify commit in the pd_dbsync_point operand.

LOB RDAREAs are not affected by this operand. Directories are reflected at the point that the COMMIT statement is issued. How data is processed depends on whether or not a LOB global buffer was allocated. If a LOB global buffer was not allocated, data is reflected immediately upon issuance of the update request. If a LOB global buffer was allocated, data is reflected at the point that the COMMIT statement is issued. However, data is also reflected whenever the global buffer becomes full.

(3) Considerations

If the information obtained by the pdbufls command indicates that there are many output operations to disk and that the update request hit rate is low, the number of global buffer sectors should be set to a large value.