面试题与答案

Informatica PowerCenter is an ETL (Extract, Transform, Load) tool used for data integration and warehousing.

A session in Informatica is a task that represents the execution of a workflow. It is the smallest unit of work in a workflow.

A repository in Informatica is a relational database that stores metadata and configuration information about the various objects managed by Informatica.

A workflow in Informatica is a set of instructions for the integration service to execute the tasks defined in a mapping.

The Aggregator transformation in Informatica is used to perform aggregate calculations such as sum, average, minimum, maximum, etc., on groups of data.

The Sequence Generator transformation in Informatica is used to generate unique sequence numbers for rows in a data set.

Informatica supports various transformations, including Aggregator, Filter, Router, Lookup, Expression, Joiner, and many others.

The Source Qualifier transformation in Informatica is used to specify properties for reading data from a relational or flat file source.

A Filter transformation in Informatica is used to filter rows based on specified conditions, allowing only the required rows to pass through.

A Parameter File in Informatica is a text file that contains parameter values used to replace placeholders in session and workflow properties at runtime.

A Router transformation in Informatica is used to filter data rows to different output groups based on specified conditions.

A reusable session in Informatica can be created by defining the session as reusable in the session properties and saving it to the repository for use in multiple workflows.

Null values in Informatica can be handled using functions like ISNULL and COALESCE, or through the use of NULL indicator ports in transformations.

A Joiner transformation in Informatica is used to combine rows from two heterogeneous sources based on a common column, similar to an SQL join operation.

ETL (Extract, Transform, Load) is a process where data is extracted from source systems, transformed, and then loaded into a data warehouse. ELT (Extract, Load, Transform) is a process where data is first extracted and loaded into the target system, and then transformations are applied.

A mapping is a set of source and target definitions linked by transformations, while a mapplet is a reusable object that contains a set of transformations.

A Router transformation in Informatica is used to route data rows to different transformation logic based on specified conditions.

The Repository Service in Informatica is responsible for managing connections to the repository and providing access to the metadata stored in the repository.

A Rank transformation in Informatica is used to select the top or bottom 'n' rows based on a specified condition or column.

A Lookup transformation in Informatica is used to look up data in a relational table or view based on a condition and retrieve related values.

A connected Lookup transformation is connected to the pipeline, while an unconnected Lookup is not connected to the pipeline and must be called by another transformation.

Parameterization in Informatica is achieved through the use of parameter files, which contain values that can be substituted into session and workflow properties at runtime.

Partitioning in Informatica involves dividing the source data into subsets to be processed in parallel, improving session performance.

Errors in Informatica can be handled using error handling strategies such as redirecting rows, terminating the session, or sending errors to a separate target.

A Normalizer transformation in Informatica is used to convert columns with repeating groups into multiple rows, making data more readable and usable.

The Data Transformation Manager (DTM) in Informatica is responsible for the execution of tasks within a session, such as reading, transforming, and loading data.

Session performance in Informatica can be improved by optimizing transformations, using partitioning, increasing cache size, and tuning session properties.

Informatica handles incremental data loading by comparing source and target data based on a specified key and loading only the changed or new records.

The Debugger in Informatica is used for testing and debugging mappings by allowing step-by-step execution and inspection of data at various points.

A Transaction Control transformation in Informatica is used to commit or roll back transactions based on specified conditions in a session.

Slowly Changing Dimensions (SCD) in Informatica can be handled using techniques such as Type 1 (overwrite), Type 2 (historical), and Type 3 (add new column).

A Target Load Plan in Informatica specifies the order in which target tables are loaded, providing control over the loading sequence in a session.

A Sorter transformation in Informatica is used to sort data based on one or more columns before passing it to the target transformation.

A Surrogate Key in Informatica is a system-generated key used to uniquely identify rows in a dimension table, often replacing natural keys for efficiency.

A Pre-Session Command in Informatica is used to execute commands or scripts before the session starts, allowing for custom initialization tasks.

The Data Masking transformation in Informatica is used to mask sensitive data in a mapping, ensuring that confidential information is not exposed.

A LookUp cache in Informatica is used to store and reuse lookup data, improving performance by reducing the number of database queries.

A Normalizer transformation in Informatica is used to transform data by converting columns with repeating groups into multiple rows, simplifying data processing.

Static cache is populated at the beginning of a session and does not change during the session, while dynamic cache can be updated during the session.

Constraint-based loading order in Informatica ensures that data is loaded into the target in a specific order based on defined constraints between transformations.

Incremental Aggregation in Informatica involves updating only the changed or new records in the source, reducing the processing load.

A Dynamic Lookup Cache in Informatica is created at runtime and allows the addition of new entries during the session.

A Persistent Cache in Informatica is a type of cache that is stored on disk and can be reused across sessions, providing improved performance.

In a Data-driven session in Informatica, the session properties and mappings are determined at runtime based on metadata, allowing dynamic control of the ETL process.

The Unconnected Stored Procedure transformation in Informatica is used to execute stored procedures that are not connected to the pipeline and do not return a value.

Dynamic Partitioning in Informatica allows the Informatica server to dynamically determine the number of partitions based on the available system resources.

A Lookup Override in Informatica allows you to override the default SQL query generated by the Lookup transformation to customize data retrieval.

A Source Filter in Informatica is used to filter rows at the source database level before they are read by the source qualifier, optimizing data extraction.