docs(cayenne): correct footer_cache_mb default in v2.1.x (50 MB when unset, not 128)

[claudespice]

Summary

The version-2.1.x Cayenne accelerator page still documents cayenne_footer_cache_mb as "Defaults to 128", but at v2.1.0 the field is footer_cache_mb: Option<usize> = None when unset, and the runtime applies it to DataFusion's metadata cache only when Some — so when unset, no explicit limit is set and DataFusion's own default file-metadata-cache limit of 50 MB applies. There is no 128 MB default in v2.1.0.

This is the correction docs#1908 made for vNext and version-2.0.x, which was missed on the version-2.1.x snapshot (it was cut around the same time as #1908 and inherited the pre-correction "128" text). vNext and 2.0.x already read correctly; v1.10.x/v1.11.x correctly keep 128 (the field was a real usize = 128 in those releases).

What changed (version-2.1.x only, 3 spots to match vNext/2.0.x):

• runtime.params table row for cayenne_footer_cache_mb
• the "Footer Cache" tuning bullet (Default: 128 MB → Default: unset — … 50 MB applies)
• the memory-budget table row (Footer cache | 128 MB → 50 MB | Unset by default …)

Source

• spiceai/spiceai @ v2.1.0:
  • crates/cayenne/src/catalog_provider.rs:52 — pub footer_cache_mb: Option<usize>
  • crates/runtime/src/builder.rs:473 — applied only if cayenne_footer_cache_mb.is_some()
• Prior correction: docs(cayenne): correct cayenne_footer_cache_mb default — no 128 MB, DataFusion 50 MB applies when unset (fixes #1887) #1908 (fixed vNext + 2.0.x; this sweeps the missed 2.1.x snapshot)

Test plan

• cd website && npm run build passes
• Scope: version-2.1.x only (vNext + 2.0.x already correct; v1.x correctly keeps 128)
• Files updated: 1

[github-actions]

✅ Pull with Spice Passed

Passing checks:

• ✅ Title meets minimum length requirement (10 characters)
• ✅ Has at least one of the required labels: area/blog, area/docs, area/cookbook, dependencies
• ✅ No banned labels detected
• ✅ Has at least one assignee: claudespice

[github-actions]

🚀 deployed to https://dcae2dc4.spiceai-org-website.pages.dev