IBM DB400 Interview Question:

What is open data path? and what is the diff b/w access path and open data path?

Submitted by: Administrator

An access path describes the order in which the rows are
retrieved from a database file. If the rows in the file are
accessed in a physical sequence, that is known as an
arrival sequence access path. If the rows need to be
processed in an ordered manner, then a keyed access path is
needed to sort the data in the specified order. With DB2
for iSeries, keyed access paths are supplied to DB2 by
creating a keyed logical file, keyed physical file, or SQL
index.

An access path and an open data path are used together to
process the rows in a database file.

The open data path (ODP) is the path through which all
input and output operations are performed on a database
file. The ODP is used to connect the requesting program
with the data in the file. As data is retrieved from or
inserted into the file, the ODP will use an access path to
navigate to a row within in the file. If the rows need to
be processed in a sorted owner, then someone will need to
supply a keyed access path by creating a keyed physical
file, keyed logical file or SQL index.

An ODP is created and used each time that a file is opened
or when an SQL statement is executed. There are ways to
have an ODP shared or reused instead of creating the ODP
each time.
Submitted by: Administrator