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

[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.

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

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/