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Martini Data Model Cursors

Cursors are a vital feature in Martini for efficiently managing large datasets. They are particularly useful when processing millions of rows, as they act as pointers to individual records in a dataset, thus conserving memory by not loading all data at once. This section delves into the use of cursors, their functionalities, limitations, and best practices within Martini.

Understanding Cursors in Martini

Cursors in Martini function similarly to arrays but come with specific limitations: - Single Iteration: Cursors can only be iterated once. - Read-Only or Write-Only: Some cursors are restricted to either reading or writing data.

When to Use Cursors

Martini employs cursors in various scenarios for efficient data handling: 1. SQL Services: For batch SQL services, models are treated as writable cursors. 2. Multi-Select SQL Services: These return cursors that are read-only. 3. Flat File Services: Cursors are used for reading and writing large files efficiently. 4. Handling Large Files: Special methods are provided for processing large text, XML, and JSON files using cursors.

Working with Cursors

Reading and Writing with Cursors

  • Automated Handling: Martini can automatically manage cursor operations in certain contexts.
  • Manual Management: For specific operations, developers can manually manipulate cursors using provided methods.

Best Practices

  • Effective Memory Management: Guidelines on using cursors without causing memory issues.
  • Error Handling: Strategies for addressing common challenges encountered when working with cursors.

Practical Examples

Example Services Demonstrating Cursors

  • Detailed examples illustrating the use of cursors in various scenarios, including:
    • SQL services for batch processes.
    • File operations through ReadFile and WriteFile services.
    • Handling large JSON and XML files.

Code Snippets

  • Real-world Examples: Include code snippets from these services to demonstrate cursor usage in practice.

Troubleshooting

Guidance on resolving typical issues that arise during cursor operations in Martini.

Performance Considerations

Discussion on the impact of cursor usage on performance and tips for optimization in large-scale data processing.