The Encoded Vector Index Probe icon indicates that the selection criteria whose predicates matched the leading key columns of the encoded vector index were used to probe directly into the distinct values represented in the index. Only those distinct values that match the specified probe selection will then be used to process the vector and generate either a temporary row number list or temporary row number bitmap.
Also referred to as: Encoded Vector Index Probe, Preload
See Tips for encoded vector index for more details.