SingleStore Vector: query not using the ANN index - EXPLAIN check

TL;DR

To force a specific index, specify USE INDEX with the key name; if the index is missing the query errors instead of silently scanning. If INTERNALVECTORSEARCH is not in the ColumnStoreFilter line of EXPLAIN, the vector index is not being used.

The error

EXPLAIN check

Fix

1. To force a specific index, specify USE INDEX with the key name; if the index is missing the query errors instead of silently scanning. Expected: You get the expected result; the problem is gone.

2. Re-run the original operation and confirm the error is gone. Expected: no error, normal output.

When to use

• You hit this exact error with SingleStore Vector.
• The symptom matches: query not using the ANN index - EXPLAIN check.

When NOT to use

• A different error message from SingleStore Vector; the cause here is specific to this error.
• Unrelated SingleStore Vector issues (different feature, different failure).
• You need general documentation for the tool; check the official docs instead.

Compatibility

Reported against SingleStore Vector. Source: https://docs.singlestore.com/db/v8.7/reference/sql-reference/vector-functions/vector-indexing/.

Variant phrasings

query not using the ANN index - EXPLAIN check

EXPLAIN check

Why it happens

A vector query runs slowly as if the vector index does not exist. Check EXPLAIN to see whether the index is used at all.

Edge cases

• If your error message differs even slightly, this is probably a different issue; search the exact text.
• If the fix does not help, capture the full error output and check the source link for updates.

Source

https://docs.singlestore.com/db/v8.7/reference/sql-reference/vector-functions/vector-indexing/

Source: A vector query runs slowly as if the vector index does not exist. Check EXPLAIN to see whether the index is used at all.

Verified resolution: [SingleStore vector-indexing docs]: if INTERNALVECTORSEARCH is not in the ColumnStoreFilter line of EXPLAIN, the vector index is not being used. Two classic causes: the query uses USE INDEX () which disables ANN indexes, and ORDER BY in the wrong direction, DOTPRODUCT needs DESC, EUCLIDEANDISTANCE needs ASC. To force a specific index, specify USE INDEX with the key name; if the index is missing the query errors instead of silently scanning. Place the USE INDEX clause right after ORDER BY.

Source URL: https://docs.singlestore.com/db/v8.7/reference/sql-reference/vector-functions/vector-indexing/