Pinecone diagnosis: query-by-id behaves unexpectedly

Diagnosis

Symptom

query(id=...) returns unexpected matches, or fails where fetch on the same id works.

Likely cause

Query-by-id runs a similarity search using the stored vector as the query; it is subject to the same top_k, filter, and namespace rules as a vector query. It is not a point lookup. The docs also note limitations on querying by id versus fetching.

Confirm it

1. Run fetch on the id: if fetch works, the record exists and the issue is query semantics.
2. Check the namespace on the query call; query-by-id still scopes to a namespace.
3. Check whether a filter is excluding the expected neighbors.

Fix

1. For point lookups use fetch, not query(id=...).
2. For find-similar-to-this-record, keep query(id=...) but set namespace, top_k, and filter deliberately.
3. If you need the vector values back too, pass include_values=True; matches do not include values by default.

Verify the fix

Fetch the id, then query by the fetched values directly and compare the match lists; they should agree.

Pinecone's querying-by-id limitations troubleshooting page and the query guide define the find-similar semantics and its limits versus fetch. Verified against live docs 2026-09-26.