IMS DB Interview Questions and Answers
Q1. What is IMS (DB/DC)?
Ans: IMS (Information Management System) is IBMs hierarchical database management gadget. It has especially components: IMS DB and IMS DC (Also realize as IMS TM)
IMS DB - IMS/Database Manager as the call implies manages the IMS databases. It is used for physical garage introduction and control and information retrieval.
IMS DC / IMS TM - IMS/Data Communications or IMS/Transaction Manager handles online transaction processing system
Q2. What are the principle manipulate blocks to be had in IMS DB?
Ans: There are 3 manipulate blocks (additionally referred to as DL/I manage blocks)
1.Database Description (DBD)
2.Program Specification Block (PSB)
3.Application Control Block (ACB)
Q3. What type of databases IMS helps?
Ans: Full-characteristic database and Fast direction database
Q4. What are the targets of DBMS in IMS?
Ans: Increases statistics independence
Reduces records redundancy
Provides records verbal exchange facilities
Reduces data preservation
Provides records integrity and safety
Provides indexing competencies
Q5. What is DL/I?
Ans: DL/I is a command-stage language to govern IMS databases. DL/I bureaucracy a bridge between software application and IMS database. It is utilized in batch and online programs to get right of entry to facts saved in IMS databases.
Every get admission to to an IMS database is through DL/I. The DL/I interface have to be known as to update or study a IMS database. DL/I lets in each sequential and random processing of a database.
Q6. How facts is saved in each IMSDB and DB2 databases?
Ans: Some enterprise packages require that the data is kept in both IMS and DB2 for z/OS databases. One such scenario is a excessive-performance manufacturing software that works with the records in an IMS database and a enterprise choice assist software that works with the same records in a DB2 for z/OS database. Production packages running in IMS Transaction Manager (IMS TM) can replace data that is saved in a DB2 for z/OS database and facts that is saved in an IMS database. If not done in a unmarried, logical unit of labor, coordinating these updates may be complex
Q7. What is a root segment?
Ans: A section that lies at the top of the hierarchy is called the root section. It is the most effective segment through which all structured segments are accessed.
Q8. What are twin segments?
Ans: Two or greater phase occurrences of a specific section type under a single parent section prevalence are known as twin segments.
Q9. What are commonplace DLI capabilities?
Ans: The common capabilities are GU, GN, GNP, GHU, GHN, REPL, ISRT, and DLET.
Q10. What is PSB and PCB?
Ans: PSB is Program Specification Block that's a collection of 1 or more PCBs.
PCB is Program Control Block which represents the application application's view of the database.
Q11. What is PROCOPT?
Ans: PROCOPT is processing alternative defined in PCB, which specifies the operations that can be achieved at the database. Different PROCOPTs that can be used are
G - Get segment from DB
I - Insert phase into DB
R - Replace phase
D - Delete segment
A - All the above operations
LS - Load Sequential in GSAM (HIDAM)
GS - Get Sequential in GSAM
Q12. What records does a DBD contain?
Ans: DBD facts includes:
1.Database name, Access approach
three.Segment name, duration, discern
4.Key area name, length, location, type
5. Search field call, period, vicinity, type.
Q13. What is a phase in IMS?
Ans: Segment is the smallest unit of data that IMS transfers to and from database. Segment may contain one or greater fields.
Q14. Which languages does IMS assist / application software languages?
Ans: COBOL, PL/1, C, VS Pascal, REXX, Ada and Assembler.
Q15. What are the two sorts of fields available in IMS DB?
Key Fields - (PROCOPT=K)
Used to sequence the database and cannot be changed
It?s the sphere inside a segment, used to pick out the incidence of the phase
used to maintain the IMS segments in ascending collection.
Search Fields - (PROCOPT=G)
Used to search for a segment, with out the phase being sequenced on that discipline
A segment need no longer have a key or seek discipline.
Both varieties of fields may be used to search the database.
Q16. What is the function of a GU name?
Ans: ‘GU’ or Get Unique works much like the random study declaration in COBOL. It is used to fetch a particular segment incidence based totally on the sphere values which can be furnished the use of Segment Search Arguments.
Q17. What is the characteristic of a GHU name?
Ans: ‘GHU’ or Get Hold Unique specifies that we are going to replace a phase after retrieval. GHU corresponds to the GU call.
Q18. What is reorganization in IMSDB?
Ans: To reclaim and consolidate loose area that has come to be fragmented due to repeated insertion and deletion of segments.
To optimize the physical storage of the database segments for maximum performance (get established segments which can be in remote blocks, which increases bodily I/O, back in the identical block as the discern or root), a state of affairs this is normally the result of high update hobby at the database.
To regulate the shape of the database, trade the scale of the database statistics sets, adjust the hierarchical direct get admission to technique (HDAM) root addressable place, and add or delete segment kinds.
Q19. What is SSA?
Ans: SSA is section search argument. It is used to retrieve a specific section or segment type from the DB.
Q20. What are qualified and unqualified calls?
Ans: IMS call with SSA is referred to as certified call. IMS call without SSA is unqualified name.
Q21. What are qualified and unqualified SSAs?
Ans: SSA which includes simplest the section call is Unqualified SSA. SSA which incorporates segment call, area call, relational operator and seek fee for the sphere call is qualified SSA.
Q22. What are command codes?
Ans: Command codes are used along with SSAs to perform additional operations. Common command codes used are
'P' - used to set parentage on a selected segment
'D' - used for path calls, to retrieve the entire hierarchical direction
Q23. What are the processing modes to be had in IMS DB?
Ans: MPP Mode - (Message Processing Program)
BMP Mode - (Batch Message Processing)
Q24. Explain IMS Software Environment?
Ans: IMS Software Environment consists of the beneath five most important additives:
DL/I Control Blocks
Q25. What is DBD?
Ans: DBD (Database Definition) is used to outline the bodily structure of the database.
One DBD for each database Created with the aid of a series of manage statements - via a technique known as DBDGEN
Used by way of DL/I every time database is used
Q26. Explain DBDGEN process?
Ans: DBDGEN control statements consists of Assembler Language macro statements. The macros are provided by means of IBM in a library named IMSVS.MACLIB. DBDGEN control statements are generally coded through the DBA and submitted to the device with JCL. That invokes a cataloged procedure usually known as DBDGEN. The DBDGEN system causes the DBDGEN manipulate statements to the processed with the aid of the assembler generating the object module. The object module is then handed to the linkage editor which, in flip, stores a load module in some other IMS Library referred to as as IMS.DBDLIB or IMSVS.DBDLIB.
The DBD technique is generally preformed handiest once for a database. All applications use the DBD in having access to the data on the database. A new DBD is typically created handiest if the physical nature of the database adjustments.
Q27. Which parameter specifies the language wherein the application program is written in PSBGEN?
Ans: The LANG parameter specifies the language wherein the utility program is written, e.G., COBOL.
Q28. Which is used to bypass the control again to the IMS control program?
Ans: GOBACK is used to pass the control again to the IMS manipulate application.
Q29. Which function is used to get a completely unique file for update reason?
Ans: ‘GHU’ code is used for Get Hold Unique. Hold feature specifies that we are going to update the phase after retrieval. The Get Hold Unique feature corresponds to the Get Unique name.
Q30. Which feature is used to retrieve phase occurrences in collection subordinate to a longtime parent phase?
Ans: ‘GNP’ code is used for Get Next inside Parent. This function is used to retrieve segment occurrences in collection subordinate to an established determine phase