The EVI Symbol Table Scan icon indicates that the entire symbol table portion of the encoded vector index will be scanned (the symbol table contains all of the distinct values in the index). Any selection criteria, whose predicates match the key columns of the encoded vector index, can then be applied against the distinct values. Only those distinct values that match the specified key selection will be selected out of the symbol table.
Also referred to as: EVI Symbol Table Scan, Preload