Export to CSV

This document lists the different implementations of CSV export in GitLab codebase.

Export type	Implementation	Advantages	Disadvantages	Existing examples
Streaming	- Query and yield data in batches to a response stream.

• Download starts immediately. | - Report available immediately. | - No progress indicator.
• Requires a reliable connection. | Export audit event log | | Downloading | - Query and write data in batches to a temporary file.
• Loads the file into memory.
• Sends the file to the client. | - Report available immediately. | - Large amount of data might cause request timeout.
• Memory intensive.
• Request expires when the user goes to a different page. | - Export Chain of Custody Report
• Export License Usage File | | As email attachment | - Asynchronously process the query with background job.
• Email uses the export as an attachment. | - Asynchronous processing. | - Requires users use a different app (email) to download the CSV.
• Email providers may limit attachment size. | - Export issues
• Export merge requests | | As downloadable link in email (*) | - Asynchronously process the query with background job.
• Email uses an export link. | - Asynchronous processing.
• Bypasses email provider attachment size limit. | - Requires users use a different app (email).
• Requires additional storage and cleanup. | Export User Permissions | | Polling (non-persistent state) | - Asynchronously processes the query with the background job.
• Frontend(FE) polls every few seconds to check if CSV file is ready. | - Asynchronous processing.
• Automatically downloads to local machine on completion.
• In-app solution. | - Non-persistable request - request expires when the user goes to a different page.
• API is processed for each polling request. | Export Vulnerabilities | | Polling (persistent state) (*) | - Asynchronously processes the query with background job.
• Backend (BE) maintains the export state
• FE polls every few seconds to check status.
• FE shows 'Download link' when export is ready.
• User can download or regenerate a new report. | - Asynchronous processing.
• No database calls made during the polling requests (HTTP 304 status is returned until export status changes).
• Does not require user to stay on page until export is complete.
• In-app solution.
• Can be expanded into a generic CSV feature (such as dashboard / CSV API). | - Requires to maintain export states in DB.
• Does not automatically download the CSV export to local machine, requires users to select 'Download'. | Export Merge Commits Report |

[!note] Export types marked as * are currently work in progress.