Provides default selectivity estimates (in parts per million) to the optimizer for most LIKE predicates.
DEFAULT_LIKE_MATCH_SELECTIVITY_PPM sets the default selectivity for generic LIKE predicates, for example, LIKE 'string%string' where % is a wildcard character.
The optimizer relies on this option when other selectivity information is not available and the match string does not start with a set of constant characters followed by a single wildcard.
If the column has either an LF index or a 1- or 2- or 3-byte FP index, the optimizer can get exact information and does not need to use this value.
Users can also specify selectivity in the query. User-supplied condition hints are described in Reference: Building Blocks, Tables, and Procedures.