Optionally ignore field when indexed field name exceeds length limit

[jordan-powers]

This PR adds an index setting index.mapping.field_name_length.ignore_dynamic_beyond_limit. When this setting is set, fields dynamically added to the mapping that would violate the index.mapping.field_name_length.limit are silently ignored instead of causing an exception and preventing indexing of the document.

Fixes #135700

[elasticsearchmachine]

Hi @jordan-powers, I've created a changelog YAML for you.

[github-actions]

🔍 Preview links for changed docs

• docs/reference/elasticsearch/index-settings/mapping-limit.md

[github-actions]

ℹ️ Important: Docs version tagging

👋 Thanks for updating the docs! Just a friendly reminder that our docs are now cumulative. This means all 9.x versions are documented on the same page and published off of the main branch, instead of creating separate pages for each minor version.

We use applies_to tags to mark version-specific features and changes.

Expand for a quick overview

When to use applies_to tags:

✅ At the page level to indicate which products/deployments the content applies to (mandatory)
✅ When features change state (e.g. preview, ga) in a specific version
✅ When availability differs across deployments and environments

What NOT to do:

❌ Don't remove or replace information that applies to an older version
❌ Don't add new information that applies to a specific version without an applies_to tag
❌ Don't forget that applies_to tags can be used at the page, section, and inline level

🤔 Need help?

• Check out the cumulative docs guidelines
• Reach out in the #docs Slack channel

[elasticsearchmachine]

Pinging @elastic/es-storage-engine (Team:StorageEngine)

[martijnvg]

LGTM 👍

[martijnvg]

Maybe also add a test where the field will not be ignored? Or update these tests to add two fields, one field that would be ignored because field name length is exceeded and one field just under this limit?

[martijnvg]

Maybe in a follow up change we can consider defaulting to true in case of logsdb and tsdb?