22.What is the use of Sparse Sequencing?
We can remove some of the index source segments from the index using sparse sequencing with secondary index database. Sparse sequencing is used to improve the performance. When some occurrences of the index source segment are not used, we can remove that. Sparse sequencing is also known as Sparse Indexing.
23.Explain Logical relationship.
A logical relationship is a path between two segments related logically and not physically. Usually a logical relationship is established between separate databases. But it is possible to have a relationship between the segments of one particular database.
24.What are logical twins?
Logical twins are the occurrences of a logical child segment type that are subordinates to a single occurrence of the logical parent segment. DL/I makes the logical child segment appear like an actual physical child segment. This is also known as virtual logical child segment.
25.What is a concatenated segment?
A logical child segment always begins with the complete concatenated key of the destination parent. This is known as Destination Parent Concatenated Key (DPCK). Always code the DPCK at the start of your segment I/O area for a logical child. In a logical database, the concatenated segment makes the connection between segments that are defined in different physical databases.
26.Explain DL/I log.
When an application program abnormally ends, it is necessary to revert the changes done by the application program, correct the errors, and re-execute it. To do this procedure, it is required to have the DL/I log.
27.What is a checkpoint?
A checkpoint is a stage where the modifications done to a database by an application program are considered complete and accurate.
28.Which database processing is very fast?
IMS DB processing is very fast as compared to DB2.
29.Which database is difficult to manage?
IMS predefined tree structure reduces flexibility and it is difficult to manage.
30.Through which segment all dependent segments are accessed?
A segment that lies at the top of the hierarchy is called the root segment. It is the only segment through which all dependent segments are accessed.