When a database is accessed, finding the desired target data in a global buffer without having to perform any physical input/output operation is called a buffer hit. When the probability of a buffer hit (buffer hit rate) is high, database access performance is stable. When HiRDB has just started, there is no information about tables and indexes in global buffers, so the buffer hit rate is low, resulting in unstable database access performance.
The global buffer residence utility (pdpgbfon) reads information about tables and indexes into global buffers in advance. If you execute pdpgbfon as soon as HiRDB has started, such as before startup of online jobs, you can expect stable database access performance.
For example, in an environment where all tables and indexes can be read from the database to a global buffer, high-speed database operations can be achieved without any physical input/output operations.
Figure 12-1 shows the effects of pdpgbfon.
Figure 12-1 Effects of pdpgbfon