docs: add server-side sampling configuration to scaling guide

[Steffen911]

Summary

Adds documentation for the LANGFUSE_INGESTION_PROCESSING_SAMPLED_PROJECTS environment variable to the self-hosting scaling guide.

Changes

• Added new "Server-side sampling per project" section to /pages/self-hosting/configuration/scaling.mdx
• Positioned under "Ingestion Throughput" section for natural discoverability
• Includes:
  • Configuration format and practical example
  • Explanation of deterministic hash-based sampling behavior
  • Trace-level sampling details
  • Comparison with client-side sampling
  • Link to existing client-side sampling documentation

Documentation approach

• Positioned as a standard performance optimization tool (not emergency-only)
• Moderate technical detail level (deterministic, hash-based, trace-level)
• Brief but comprehensive (~200 words)
• Follows established patterns from other sections in the scaling guide
• Links to related client-side sampling docs for complete picture

Location rationale

The scaling page was chosen because:

• Feature is specifically for ingestion performance optimization
• Page already documents similar advanced performance features
• Listed under "Essential" in navigation for good discoverability
• Users optimizing performance will naturally find it here

🤖 Generated with Claude Code

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Important

Adds server-side sampling configuration documentation to the Langfuse scaling guide.

• Documentation:
  • Adds "Server-side sampling per project" section to scaling.mdx.
  • Details LANGFUSE_INGESTION_PROCESSING_SAMPLED_PROJECTS environment variable for configuring sampling rates.
  • Explains deterministic hash-based sampling, trace-level sampling, and comparison with client-side sampling.
  • Positioned under "Ingestion Throughput" for discoverability.
  • Links to client-side sampling documentation.

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Project	Deployment	Preview	Updated (UTC)
langfuse-docs	Ready	Preview	Nov 7, 2025 11:09am

[Steffen911]

Currently this is limited to ingestions via the /api/public/ingestion route and does not apply to OTel spans. Needs server side update, before it can be published.

[github-actions]

📦 Next.js Bundle Analysis for langfuse-docs

This analysis was generated by the Next.js Bundle Analysis action. 🤖

One Page Changed Size

The following page changed size from the code in this PR compared to its base branch:

Page	Size (compressed)	First Load	% of Budget (350 KB)
/self-hosting/configuration/scaling	59.75 KB	455.89 KB	130.25% (🟡 +0.25%)

Details

Only the gzipped size is provided here based on an expert tip.

First Load is the size of the global bundle plus the bundle for the individual page. If a user were to show up to your website and land on a given page, the first load size represents the amount of javascript that user would need to download. If next/link is used, subsequent page loads would only need to download that page's bundle (the number in the "Size" column), since the global bundle has already been downloaded.

Any third party scripts you have added directly to your app using the <script> tag are not accounted for in this analysis

The "Budget %" column shows what percentage of your performance budget the First Load total takes up. For example, if your budget was 100kb, and a given page's first load size was 10kb, it would be 10% of your budget. You can also see how much this has increased or decreased compared to the base branch of your PR. If this percentage has increased by 20% or more, there will be a red status indicator applied, indicating that special attention should be given to this. If you see "+/- <0.01%" it means that there was a change in bundle size, but it is a trivial enough amount that it can be ignored.