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Karol Nowacki 6bc88e817f vector_search: fix SELECT on local vector index

Queries against local vector indexes were failing with the error:
"ANN ordering by vector requires the column to be indexed using 'vector_index'"

This was a regression introduced by 15788c3734, which incorrectly
assumed the first column in the targets list is always the vector column.
For local vector indexes, the first column is the partition key, causing
the failure.

Previously, serialization logic for the target index option was shared
between vector and secondary indexes. This is no longer viable due to
the introduction of local vector indexes and vector indexes with filtering
columns, which have  different target format.

This commit introduces a dedicated JSON-based serialization format for
vector index targets, identifying the target column (tc), filtering
columns (fc), and partition key columns (pk). This ensures unambiguous
serialization and deserialization for all vector index types.

This change is backward compatible for regular vector indexes. However,
it breaks compatibility for local vector indexes and vector indexes with
filtering columns created in version 2026.1.0. To mitigate this, usage
of these specific index types will be blocked in the 2026.1.0 release
by failing ANN queries against them in vector-store service.

Fixes: SCYLLADB-895

2026-03-30 16:46:48 +02:00

825 B

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Vector index in Scylla

Vector indexes are custom indexes (USING 'vector_index'). Their target option in system_schema.indexes uses following format:

Simple single-column vector index (v): just the (escaped) column name, e.g. v
Vector index with filtering columns (v, f1, f2): JSON with tc (target column) and fc (filtering columns): {"tc":"v","fc":["f1","f2"]}
Local vector index ((p1, p2), v): JSON with tc and pk (partition key columns): {"tc":"v","pk":["p1","p2"]}
Local vector index with filtering columns ((p1, p2), v, f1, f2): JSON with tc, pk, and fc: {"tc":"v","pk":["p1","p2"],"fc":["f1","f2"]}

The target option acts as the interface for the vector-store service, providing the metadata necessary to determine which columns are indexed and how they are structured.

825 B Raw Blame History

Vector index in Scylla

825 B

Raw Blame History