10 Natural Adabas Interview Questions and Answers

Natural Adabas is a robust and high-performance database management system designed for large-scale enterprise applications. Known for its reliability and efficiency, it is widely used in industries that require complex data processing and high transaction volumes. Its integration with Natural, a fourth-generation programming language, allows for seamless development and maintenance of applications, making it a valuable skill for IT professionals.

This article offers a curated selection of interview questions tailored to Natural Adabas. By reviewing these questions and their detailed answers, you will gain a deeper understanding of the system’s intricacies and be better prepared to demonstrate your expertise in interviews.

Natural Adabas Interview Questions and Answers

1. Explain how data is stored in Adabas.

Adabas (Adaptable Database System) is a high-performance, transactional database management system designed for large-scale applications. Data in Adabas is stored efficiently using several components:

• Data Storage Architecture: Adabas uses an inverted list architecture, separating data storage from indexing for rapid retrieval without extensive scanning.
• Data Storage Components:
  • *Data Storage (ASSO):* Stores actual data records in a compressed format.
  • *Index Storage (INDEX):* Maintains indexes for quick record location based on key values.
  • *Work Storage (WORK):* Used for temporary storage during operations like sorting and merging.
• Data Compression: Adabas employs field-level and record-level compression to reduce storage needs and enhance performance.
• Data Access: Offers multiple access methods, including direct access via keys and sequential access for batch processing.

2. What are the different types of fields in Adabas?

Adabas categorizes fields into several types, each serving a specific purpose:

• Elementary Fields: Store individual data items, with various data types like alphanumeric or decimal.
• Group Fields: Logically group related elementary fields without storing data themselves.
• Periodic (PE) Fields: Store multiple occurrences of a group of fields within a single record.
• Multiple-Value (MU) Fields: Enable storage of multiple values for a single field within a record.
• Descriptor Fields: Used for indexing and searching, with types like simple descriptors or superdescriptors.

3. How do you handle error handling in Natural programs accessing Adabas?

Error handling in Natural programs accessing Adabas is important for data integrity and application reliability. Natural provides several mechanisms:

• ON ERROR Statement: Defines a block of code executed when an error occurs, allowing graceful handling.
• ERROR-NR System Variable: Holds the error number of the last error, helping determine the type of error.
• RETRY Statement: Used within an ON ERROR block to retry operations that caused errors.
• Adabas Response Codes: Check response codes from Adabas calls for detailed information on operation success or failure.

Example:

DEFINE DATA LOCAL
1 EMPLOY-VIEW VIEW OF EMPLOYEES
  2 PERSONNEL-ID
  2 NAME
END-DEFINE

READ EMPLOY-VIEW BY PERSONNEL-ID
  ON ERROR
    IF ERROR-NR = 3009
      /* Handle specific error, e.g., record not found */
    ELSE
      /* Handle other errors */
    END-IF
  END-ERROR
  /* Process the record */
END-READ

4. Describe the purpose and use of the Adabas Data Dictionary (FDT).

The Adabas Data Dictionary, or Field Definition Table (FDT), serves as a blueprint for data stored in an Adabas file. It defines the structure, types, and attributes of each field within the file. The FDT is created when a new Adabas file is defined and remains associated with that file throughout its lifecycle.

The primary purposes of the FDT include:

• Defining Field Attributes: Specifies the type, length, and format of each field for consistent storage and retrieval.
• Data Integrity: Helps maintain data integrity and consistency across the database.
• Optimized Data Access: Allows Adabas to optimize data access and retrieval processes.
• Facilitating Data Management: Provides a clear schema for tasks like backups and migrations.

5. How would you optimize a query in Natural to improve performance when accessing Adabas?

Optimizing a query in Natural to improve performance when accessing Adabas involves several strategies:

• Use of Descriptors: Ensure fields in search criteria are defined as descriptors for faster searches.
• Efficient Indexing: Properly index frequently queried fields to reduce data scanning.
• Minimize Data Retrieval: Retrieve only necessary fields and records, avoiding SELECT *.
• Optimize Search Criteria: Use specific criteria to limit records retrieved.
• Use of Read Logical: Prefer READ LOGICAL over READ PHYSICAL for faster access using descriptor values.
• Buffer Pool Management: Ensure the buffer pool is adequately sized and managed to reduce I/O operations.
• Avoid Unnecessary Sorting: Minimize SORT operations, ensuring efficiency when necessary.

6. What are the security features available in Adabas?

Adabas offers several security features to ensure data protection:

• Authentication: Supports user authentication, integrating with systems like LDAP.
• Authorization: Provides role-based access control to manage user permissions.
• Encryption: Supports data encryption at rest and in transit.
• Auditing: Includes auditing capabilities to track and log user activities.
• Data Integrity: Ensures data integrity through transaction management and consistency checks.

7. Explain the role of Adabas utilities and provide examples of commonly used ones.

Adabas utilities are tools designed to manage and maintain databases, performing tasks like data loading, unloading, backup, and recovery. Commonly used utilities include:

• ADALOD: Loads data into a database, handling large volumes and ensuring correct formatting.
• ADAUNLOAD: Unloads data for migration, backup, or archiving.
• ADABCK: Backs up the database, ensuring a consistent snapshot for recovery.
• ADAREP: Generates reports on database status and performance.
• ADAFRM: Formats database files, preparing them with necessary structures.

8. Explain the concept of Adabas Parallel Services and its benefits.

Adabas Parallel Services allows multiple instances of the Adabas nucleus to run in parallel on a single database, using a shared cache and lock management system to ensure data consistency.

Benefits include:

• Improved Performance: Distributes workload across instances for enhanced performance.
• Scalability: Allows adding more instances to handle increased workloads.
• High Availability: Other instances continue operating if one fails.
• Resource Optimization: Balances load across instances for better resource use.

9. How does Adabas handle transaction management and concurrency control?

Adabas handles transaction management and concurrency control to ensure data integrity and consistency.

For transaction management, Adabas uses “Logical Transaction” to group operations into a single unit of work, ensuring atomicity. A two-phase commit protocol ensures consistent transaction commitment across databases.

Concurrency control is managed using a locking mechanism, with record-level and file-level locks to control data access. This prevents interference between concurrent transactions, maintaining data consistency. Adabas also supports optimistic concurrency control, allowing transactions to proceed without initial locking but validating before committing to ensure no conflicts.

10. Describe the role of Predict in the Natural environment.

Predict serves as a metadata management tool in the Natural environment, helping define, document, and manage data structures and their relationships.

Key roles include:

• Data Definition: Allows users to define data structures, ensuring consistent documentation.
• Data Documentation: Provides documentation capabilities for data elements.
• Impact Analysis: Performs impact analysis to assess effects of changes in data structures.
• Data Integrity: Helps maintain data integrity and consistency across the environment.
• Integration with Natural: Tightly integrated with the Natural development environment for streamlined development.