Data access on DB2 UDB for iSeries: data access paths and methods

 

Data access methods are used to process queries and access data.

In general, the query engine has two kinds of raw material with which to satisfy a query request:

There are actually only two types of permanent database objects that can be used as source material for a query — tables and indexes (binary radix and encoded vector indexes). In addition, the query engine may need to create temporary objects or data structures to hold interim results or references during the execution of an access plan. The DB2® UDB Symmetric Multiprocessing feature provides the optimizer with additional methods for retrieving data that include parallel processing. Finally, the optimizer uses certain methods to manipulate these objects.

 

Parent topic:

Performance and query optimization