IMS DB Interview Questions and Answers: If you’re preparing for an IMS DB interview, then you know how important it is to be well-versed in the technical aspects of the software. IMS DB is a database management system that has been in use for decades and is still widely used today. As a result, there is a high demand for professionals who are skilled in IMS DB. To help you prepare, we have compiled a list of the top 100 IMS DB interview questions and answers.
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IMS DB Technical Interview Questions
Whether you’re a seasoned professional or a fresher looking to start your career in IMS DB, these IMS DB Interview Questions for Freshers will give you a good understanding of the technical aspects of the software and help you prepare for your interview. So, let’s dive into the latest IMS DB interview questions and answers and get ready to ace your next IMS DB technical interview!
Top 100 IMS DB Interview Questions and Answers
1. What is IMS DB?
Answer: IMS DB is a hierarchical database management system developed by IBM. It is used to manage large volumes of data for high-speed transaction processing.
2. What is the difference between a hierarchical database and a relational database?
Answer: A hierarchical database organizes data in a tree-like structure where each record has one parent and many children. A relational database organizes data in tables with columns and rows.
3. What is the IMS DB database structure?
Answer: The IMS DB database structure is made up of a set of hierarchical levels called segments. Each segment contains one or more fields, and each field contains one or more values.
4. What are the main control blocks available in IMS DB?
Answer: IMS DB (IMS Database) provides various control blocks that help manage and control database access and processing. Some of the main control blocks available in IMS DB include:
- PCB (Program Communication Block): PCB is used to communicate between the application program and the IMS DB system. It contains information about the database record or set that the program is requesting, including the segment name, key value, and database name.
- PSB (Program Specification Block): PSB is used to define the access method, database name, and PCBs required by an application program to access the database.
- DBD (Database Description): DBD is a data structure that describes the layout of the database, including the names of segments, fields, and their attributes. The DBD is used to generate the PCBs required by the application program.
- ACB (Access Control Block): ACB is used to manage database access and contains information about the database, such as the type of access required (read, write, or update), the location of the database, and the security requirements.
- PCB Pool: PCB pool is a set of PCBs that are preallocated and used by the application program to communicate with the IMS DB system. PCB pool helps reduce the overhead of allocating and deallocating PCBs during runtime.
- MFS (Message Format Service): MFS is used to define the format of messages that are exchanged between the application program and the IMS DB system. MFS can be used to format both input and output messages.
5. What is a root segment?
Answer: The topmost segment in a hierarchical data structure is known as the root segment. This segment is unique as it serves as the sole entry point to access all dependent segments in the hierarchy.
6. What are twin segments?
Answer: When there are multiple occurrences of a particular segment type under a single parent segment occurrence in a hierarchical data structure, they are referred to as twin segments.
7. What are common DLI functions?
Answer: The common functions are GU, GN, GNP, GHU, GHN, REPL, ISRT, and DLET.
8. What is the syntax of a qualified SSA in IMS DB?
Answer: A qualified SSA in IMS DB has the following syntax:
| segment-name(key-field-value,parent-segment-name,parent-key-field-value |
9. What is a GOBACK statement?
Answer: To transfer control back to the IMS control program, a Goback statement is utilized.
10. Which is the first statement in COBOL-IMS programs?
Answer: The entry statement is the first statement after the procedure division.
11. What is the use of Sparse Sequencing?
Answer: Sparse sequencing, also known as Sparse Indexing, is a technique utilized with secondary index databases to enhance performance. By removing certain index source segments from the index that are not utilized, we can improve the efficiency of sparse sequencing.
12. How can we access the data in IMS DB?
Answer: Data can be processed in both ways: Sequential & Random.
13. What does SENSEG stands for?
Answer: Segment Level Sensitivity (SENSEG) is a database attribute that defines a program’s access to specific parts of the database, and it is identified at the segment level.
14. What is a database segment?
Answer: A database segment is a group of related data fields in IMS DB. Segments are arranged in a hierarchical structure, with each segment being a child of the segment above it.
15. What is a database field?
Answer: A database field is a unit of data in a segment. It contains a single value or multiple values that are related to each other.
16. What is a database record?
Answer: A database record is a collection of related fields that make up a single unit of data. In IMS DB, records are organized in a hierarchical structure.
17. What is a database key?
Answer: A database key is a field or set of fields that uniquely identify a record in a database. Keys are used to retrieve specific records from the database.
18. What is the function of the IMS DB control region?
Answer: The IMS DB control region is responsible for managing the database and controlling access to it. It also handles system maintenance tasks such as backup and recovery.
19. What are the objectives of DBMS in IMS?
- Increases data independence
- Reduces data maintenance
- Provides data integrity and security
- Provides indexing capabilities
- Reduces data redundancy
- Provides data communication facilities
20. What is a database buffer?
Answer: A database buffer is an area of memory used to store data that has been read from or written to the database. It is used to improve database performance by reducing the number of physical I/O operations.
21. What is the syntax of a PCB mask in IMS DB?
Answer: A PCB mask in IMS DB has the following syntax:
| segment-name.mask-value |
22. What is the role of the database administrator in IMS DB?
Answer: The database administrator is responsible for managing the IMS DB system and ensuring that it runs smoothly. This includes tasks such as database design, performance tuning, and backup and recovery.
23. What is a transaction in IMS DB?
Answer: A transaction in IMS DB is a sequence of database operations that are treated as a single unit of work. Transactions are used to ensure data consistency and integrity.
24. What is the difference between a logical unit of work and a physical unit of work?
Answer: A logical unit of work is a set of related database operations that are grouped together for processing. A physical unit of work is a group of database operations that are executed together as a single unit.
25. What is PROCOPT?
PROCOPT is a processing option that is defined in a PCB (Program Communication Block), and it specifies the operations that can be performed on the database. There are various PROCOPT options available that can be used to determine how a particular database record or set should be accessed or modified.
- G – Get segment from DB
- I – Insert segment into DB
- R – Replace segment
- D – Delete segment
- A – All the above operations
- LS – Load Sequential in GSAM (HIDAM)
- GS – Get Sequential in GSAM
26. What is a database checkpoint?
Answer: A database checkpoint is a point in time where the IMS DB system saves information about the current state of the database. It is used to facilitate recovery in the event of a system failure.
27. What is the syntax of a GU call in IMS DB?
Answer: A GU (Get Unique) call in IMS DB has the following syntax:
| CALL ‘CBLTDLI’ USING GU-PCB, GU-QUAL-SSA, GU-IOSB. |
28. What is a database log?
Answer: A database log is a record of all database operations that have been performed since the last database checkpoint. It is used to facilitate recovery in the event of a system failure.
29. What is the difference between a full backup and an incremental backup?
Answer: A full backup is a backup of the entire database. An incremental backup is a backup of only the data that has changed since the last backup.
30. What information does a DBD contain?
DBD information includes:
- Database name, Access method
- Dataset name
- Segment name, length, parent
- Key field name, length, location, type
- Search field name, length, location, type.
31. What is a database recovery?
Answer: Database recovery is the process of restoring a database to a consistent state after a system failure. This involves using backups and logs to restore lost data.
32. What is the role of the database buffer manager in IMS DB?
Answer: The database buffer manager is responsible for managing the database buffer. It allocates and deallocates buffer space as needed, and ensures that data is written to and read from the buffer efficiently.
33. What are command codes?
Answer: Command codes are used along with SSAs to perform additional operations. Common command codes used are
‘P’ – used to set parentage on a particular segment
‘D’ – used for path calls, to retrieve the entire hierarchical path
34. What is the role of the IMS DB online region?
Answer: The IMS DB online region is responsible for processing online transactions. It receives requests from users, processes them, and returns results.
35. What is the syntax of an ISRT call in IMS DB?
Answer: An ISRT (Insert) call in IMS DB has the following syntax:
| CALL ‘CBLTDLI’ USING ISRT-PCB, ISRT-QUAL-SSA, ISRT-DATA, ISRT-IOSB. |
36. What is a message queue?
Answer: A message queue is a data structure used to store messages that are waiting to be processed. In IMS DB, message queues are used to manage communication between different regions of the system.
37. Explain IMS Software Environment?
Answer: IMS Software Environment consists of the below five main components:
- IMS DB
- DL/I
- DL/I Control Blocks
- IMS DC
- Application Programs
38. What is a program-controlled transaction?
Answer: A program-controlled transaction is a transaction that is initiated by a program rather than by a user. It is typically used to perform batch processing tasks.
39. What is a hierarchy path?
A hierarchy path is a path that begins at the root node, traverses through intermediate levels in the hierarchy, and ends at a segment located at the bottom of the hierarchy. This path is used to identify a specific node or object within a hierarchical data structure.
40. How does IMS DB differ from other database management systems?
Answer: IMS DB differs from other DBMS in that it stores data in a hierarchical structure rather than a relational structure.
41. What is a database block in IMS DB?
Answer: A database block is a physical unit of storage in IMS DB. It is a collection of one or more database records.
42. What is a DBD in IMS DB?
Answer: DBD stands for Database Description. It is used to describe the structure and characteristics of an IMS DB database.
43. What is a DL/I call in IMS DB?
Answer: A DL/I call is a request made by an application program to IMS DB to access or manipulate database records.
44. What is a GU call in IMS DB?
Answer: A GU (Get Unique) call is a DL/I call used to retrieve a specific record from an IMS DB database.
45. What is the syntax of a DL/I batch program in IMS DB?
Answer: A DL/I batch program in IMS DB has the following syntax:
| //JOBNAME JOB (ACCOUNT),… //STEPLIB DD DSN=IMS.RESLIB,DISP=SHR //SYSPRINT DD SYSOUT=* //SYSIN DD * DLI BATCH PCB=pcb-name, PSB=psb-name, SEGNAME=segment-name, DLI FUNC=function-code, DLI SSA=qualified-ssa, DLI DATA=data-value, DLI IOSB=iosb-name /* |
46. What is an ISRT call in IMS DB?
Answer: An ISRT (Insert) call is a DL/I call used to insert a new record into an IMS DB database.
47. What is the function of a DBDGEN utility in IMS DB?
Answer: The DBDGEN utility is used to generate a DBD based on the structure and characteristics of an IMS DB database.
48. What is a qualified SSA in IMS DB?
Answer: A qualified SSA (Segment Search Argument) is used to specify a particular segment or record within an IMS DB database.
49. What is a PSB override in IMS DB?
Answer: A PSB override is a mechanism that allows an application program to modify the communication requirements specified in a PSB.
50. What is the difference between a full-function PCB and a fast-path PCB in IMS DB?
Answer: A full-function PCB supports all DL/I calls, while a fast-path PCB supports only a limited set of DL/I calls.
51. What is the function of a PSBGEN utility in IMS DB?
Answer: The PSBGEN utility is used to generate a PSB for an application program based on the program-to-database communication requirements specified in the program.
52. What is a secondary index?
Answer: A secondary index is an index that is created on a field other than the primary key. It is used to speed up searches on fields that are not part of the primary key.
53. What is a PSB?
Answer: A PSB (Program Specification Block) is a control block used to define the communication between IMS DB and application programs.
54. What is a PCB?
Answer: A PCB (Program Communication Block) is a control block used to define the communication between IMS DB and individual transactions.
55. What is the role of the database recovery control program (DBRC)?
Answer: The DBRC is responsible for managing backup and recovery operations in IMS DB. It coordinates the creation and management of backup sets, and handles the recovery of the database in the event of a failure.
56. What is a database shadowing?
Answer: Database shadowing is the process of maintaining a synchronized copy of the database on a separate device. This is done to improve system availability and to reduce the risk of data loss.
57. What is a database federation?
Answer: Database federation is the process of integrating multiple databases into a single, unified system. This can improve data sharing and simplify data management.
58. What is a database index?
Answer: A database index is a data structure that is used to speed up the retrieval of data from a database. It is created on one or more fields and contains a pointer to the location of the data in the database.
59. What is a database trigger?
Answer: A database trigger is a piece of code that is automatically executed in response to a specific event in the database. Triggers can be used to enforce business rules, audit data changes, or perform other tasks.
60. What is a stored procedure?
Answer: A stored procedure is a precompiled block of code that can be executed on the database server. Stored procedures can be used to improve performance, simplify programming, and enforce business rules.
61. What is the difference between a cursor and a cursor variable?
Answer: A cursor is a mechanism used to retrieve data from a database one row at a time. A cursor variable is a pointer to a cursor that can be used to access its data.
62. What is the role of the database security administrator?
Answer: The database security administrator is responsible for managing the security of the database. This includes tasks such as creating and enforcing security policies, managing user accounts, and auditing database activity.
63. What is the difference between a clustered index and a non-clustered index?
Answer: A clustered index determines the physical order of data in a table. A non-clustered index is a separate data structure that points to the data in a table.
64. What is the purpose of a checkpoint?
Answer: A checkpoint is a mechanism used to ensure that data is written from the buffer to the database file. It is typically used to minimize data loss in the event of a system failure.
65. What is the purpose of the IMS DB Fast Path?
Answer: The IMS DB Fast Path is used to support high-speed retrieval of data in a database. It allows users to search for data in a non-sequential manner, and can improve system performance.
66. What is a database constraint?
Answer: A database constraint is a rule that is used to enforce data integrity in a database. Constraints can be used to ensure that data meets specific criteria, such as being unique, not null, or within a specific range.
67. What is the role of the database buffer?
Answer: The database buffer is a temporary storage area used to hold data that is being read from or written to the database. It helps to improve system performance by reducing the number of physical reads and writes to the database file.
68. What is a database cursor?
Answer: A database cursor is a pointer used to navigate through a set of data returned by a database query. It allows the application to fetch and process individual rows of data one at a time.
69. What is a database view?
Answer: A database view is a virtual table that is based on the result of a query. It is used to simplify the complexity of a database by presenting a subset of data in a way that is more meaningful to the user.
70. What is a rollback segment?
Answer: A rollback segment is a data structure used to store information about transactions that are in progress. It is used to rollback or undo changes made to the database in case of a system failure or other issue.
71. What is a deadlock?
Answer: A deadlock is a situation where two or more transactions are waiting for each other to release resources. This can result in a system deadlock where no transactions can proceed.
72. What is a logical database?
Answer: A logical database is a representation of a database that is independent of the physical storage of data. It is used to provide a high-level view of the data and to simplify application development.
73. What is the role of the database administrator?
Answer: The database administrator is responsible for managing and maintaining the database. This includes tasks such as creating and modifying database structures, monitoring database performance, and ensuring data security and integrity.
74. What is a database tablespace?
Answer: A database tablespace is a logical storage unit used to store tables and indexes. It is typically implemented as one or more files on disk.
75. What is the role of the transaction manager?
Answer: The transaction manager is responsible for managing the flow of transactions in a database system. It ensures that transactions are atomic, consistent, isolated, and durable (ACID).
76. What is a foreign key?
Answer: A foreign key is a column or set of columns in a table that refers to the primary key of another table. It is used to establish a relationship between the two tables.
77. What is a database transaction?
Answer: A database transaction is a sequence of operations that are treated as a single unit of work. Transactions are typically used to ensure data consistency and integrity, and to provide the ability to rollback changes in the event of a system failure.
78. What is a database backup?
Answer: A database backup is a copy of the database that is taken at a specific point in time. Backups are typically used to restore data in the event of a system failure, data corruption, or other issue.
79. What is a database restore?
Answer: A database restore is the process of copying data from a backup to the database. Restores are typically used to recover from data loss or corruption, or to migrate data to a new system.
80. What is database normalization?
Answer: Database normalization is the process of organizing data in a database to reduce redundancy and improve data integrity. Normalization involves dividing larger tables into smaller, more specialized tables and defining relationships between them.
81. What is a database transaction log?
Answer: A database transaction log is a file that records all changes made to the database. The transaction log is used to ensure data consistency and to provide the ability to rollback changes in the event of a system failure.
82. What is a database lock?
Answer: A database lock is a mechanism used to prevent multiple users from accessing the same data simultaneously. Locks can be used to ensure data consistency and to prevent conflicts between users.
83. What is a database connection pool?
Answer: A database connection pool is a cache of database connections that can be used to improve the performance of database applications. Connection pooling allows multiple users to share a pool of connections, reducing the overhead of establishing and tearing down connections.
84. What is a database query plan?
Answer: A database query plan is a description of the steps the database engine will take to execute a query. The query plan is generated by the query optimizer and can be used to analyze and optimize query performance.
85. What is a database buffer cache?
Answer: A database buffer cache is a region of memory used to cache frequently accessed data in a database. The buffer cache can improve database performance by reducing the number of disk reads required to access data.
86. What is a database deadlock detector?
Answer: A database deadlock detector is a mechanism used to detect and resolve deadlocks in a database system. The detector monitors transactions and resource usage to identify potential deadlocks, and can take action to resolve them if necessary.
87. What is a database partitioning?
Answer: Database partitioning is the process of dividing a large table into smaller, more manageable pieces called partitions. Partitioning can improve performance, simplify management, and support better data distribution.
88. What is a database replication?
Answer: Database replication is the process of copying data from one database to another. Replication can be used to improve availability, support load balancing, and enable disaster recovery.
89. What is a database sharding?
Answer: Database sharding is the process of dividing a database into smaller, more manageable pieces called shards. Sharding can improve performance, simplify management, and support better data distribution.
90. What is a database mirroring?
Answer: Database mirroring is the process of creating an exact copy of a database on another server. Mirroring can be used to improve availability and enable disaster recovery.
91. What is a database failover?
Answer: Database failover is the process of switching to a backup server in the event of a primary server failure. Failover can be used to improve availability and reduce downtime.
92. What is a database security model?
Answer: A database security model is a set of rules and procedures used to ensure data security within a database system. The security model typically includes access control mechanisms, encryption, auditing, and other security features.
93. What is a clustered index?
Answer: A clustered index is an index in which the data in the table is physically ordered based on the values in the index. Clustered indexes can improve query performance for certain types of queries.
94. What is a non-clustered index?
Answer: A non-clustered index is an index in which the data in the table is not physically ordered based on the values in the index. Non-clustered indexes can improve query performance for certain types of queries.
95. What is a composite index?
Answer: A composite index is an index that is created on multiple columns of a table. Composite indexes can improve query performance for queries that involve multiple columns.
96. What is a covering index?
Answer: A covering index is an index that contains all the columns required by a query, so that the query can be satisfied entirely from the index without needing to access the underlying table. Covering indexes can improve query performance by reducing the amount of data that needs to be read from disk.
97. What is a materialized view?
Answer: A materialized view is a pre-computed view of data that is stored in a separate table. Materialized views can improve query performance by providing a pre-computed result set that can be accessed more quickly than the original query.
98. What is a trigger?
Answer: A trigger is a special type of stored procedure that is automatically executed in response to certain events, such as changes to data in a table. Triggers can be used to enforce business rules, maintain data integrity, and perform other tasks.
99. What is a database schema?
Answer: A database schema is a description of the structure of a database, including tables, columns, indexes, and other objects. The schema provides a blueprint for the database and is used to ensure data consistency and integrity.
100. What is a database query?
Answer: A database query is a request for data from a database, typically in the form of an SQL statement. Queries can be used to retrieve, update, and delete data from a database, and can be used to perform complex analysis and reporting tasks.
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