Скачать или смотреть Creating External Tables in Oracle: Overcoming Schema Boundaries with DBMS_CLOUD

Discover how to use `DBMS_CLOUD` to create external tables in Oracle, while navigating schema limitations and permissions.
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Creating External Tables in Oracle Using the DBMS_CLOUD Package

In the world of cloud computing and data management, Oracle’s DBMS_CLOUD package has become an essential tool for interacting with external data sources. One common use case is creating external tables for types of files, like Parquet, that are stored in cloud storage. However, many users encounter challenges when attempting to execute procedures across different schemas. In this post, we’ll discuss a specific problem and its current limitations when trying to create external tables in multiple schemas using DBMS_CLOUD.

The Problem: Cross-Schema Procedure Calls

Imagine you have a well-defined procedure in Schema A that leverages DBMS_CLOUD to create external tables, such as those from Parquet files. Your ideal scenario involves calling this procedure from Schema B but creating the external table in Schema A.

However, users often run into issues such as:

Insufficient Permissions: When executing the procedure from Schema B, the default permissions may lead to errors, preventing them from creating an external table in Schema A.

Identity Management: Adding AUTHID CURRENT USER can solve some permission issues but shifts the creation responsibility to Schema B, leading to unintended behavior.

Here’s what a generic code snippet for creating an external table might look like:

[[See Video to Reveal this Text or Code Snippet]]

The Solution: Current Limitations

After analyzing the problem and possible configurations, it’s essential to acknowledge a significant limitation in the current architecture of Oracle’s DBMS_CLOUD package:

Direct Cross-Schema Creation Not Supported: As of now, it is not possible to create external tables in one schema while invoking the procedure from another schema. Hence, any attempt to call the external table creation procedure defined in Schema A from Schema B will result in permission errors.

While this can be frustrating for those working across multiple schemas, it is crucial to understand that Oracle may consider introducing this capability in future updates, but for now, users must work within these constraints.

Workarounds and Future Considerations

While direct workarounds for this issue are limited, here are a few tips to consider:

Use a Scheduler or Job Queue: Consider setting up a job on Schema A that monitors requests or triggers from Schema B. This method can encapsulate the logic without direct interaction.

Communicate: If possible, discuss with your database administration team about consolidating procedures or modifying permissions temporarily for specific tasks.

Stay Updated: Keep an eye on Oracle's updates regarding DBMS_CLOUD. Enhancements may introduce more flexibility regarding schema management and permissions.

Conclusion

In summary, while the DBMS_CLOUD package offers powerful capabilities for working with external tables, the current limitations regarding schema interactions can pose challenges for developers. Understanding these constraints allows developers to better plan their database designs and workflows while awaiting potential enhancements from Oracle.

For now, embracing the limitations and adapting workflows accordingly is the best course of action. Continue exploring and innovating in your database solutions, and stay informed about any changes in the Oracle environment that could enhance your productivity.