Related Issues

OpenSearch's indices.get_mapping() and indices.get() APIs always key their response by the real (concrete) index name, not by the alias name used in the request. Every call site that did mapping[self._index] would raise KeyError when self._index was an alias.

Proposed Changes:

document_store.py — 6 call sites fixed using actual_index = next(iter(response)):

• _ensure_index_exists / _ensure_index_exists_async — reading mappings on startup
• delete_all_documents / delete_all_documents_async — reading index settings before recreation
• count_unique_metadata_by_filter / count_unique_metadata_by_filter_async — reading field mappings
• get_metadata_fields_info / get_metadata_fields_info_async — reading field mappings

Alias guard for destructive recreation: delete_all_documents(recreate_index=True) now raises DocumentStoreError early when self._index is an alias. Deleting and recreating through an alias would drop the backing index and create a new concrete index named after the alias, permanently breaking the alias relationship. The recreate_index=False (delete-by-query) path is unaffected and works normally with aliases.

How did you test it?

Unit tests (mocked):

• test_delete_all_documents_recreate_raises_for_alias / _works_for_concrete_index (sync + async variants)
• test_ensure_index_exists_{direct_index,with_alias,creates_index,no_create} (sync + async variants, added in prior commits)

Integration tests:

• test_document_store_with_alias / test_document_store_async_with_alias — basic read/write via alias
• test_delete_all_documents_with_alias / async — asserts DocumentStoreError with recreate_index=True
• test_delete_all_documents_no_recreate_with_alias / async — verifies delete-by-query clears all docs and index remains writable
• test_count_unique_metadata_by_filter_with_alias / async — mapping lookup works through alias
• test_get_metadata_fields_info_with_alias / async — mapping lookup works through alias

Notes for the reviewer

Checklist

• I have read the contributors guidelines and the code of conduct
• I have updated the related issue with new insights and changes
• I added unit tests and updated the docstrings
• I've used one of the conventional commit types for my PR title: fix:, feat:, build:, chore:, ci:, docs:, style:, refactor:, perf:, test:.