Semantic cache distance measure support

Semantic cache distance measure support

Apigee hybrid v1.17.0 adds support for non-default Vertex AI Vector Search distance measures in the SemanticCacheLookup policy. A new optional <DistanceMeasureType> element accepts DOT_PRODUCT_DISTANCE (the default, and the existing behavior), COSINE_DISTANCE, SQUARED_L2_DISTANCE, and L1_DISTANCE. The policy compares <Threshold> in the direction the declared measure implies, so declaring a non-default measure requires re-tuning the threshold in the same edit.

For more information, see SemanticCacheLookup policy.