Provides default selectivity estimates (in parts per million) to the optimizer for leading constant LIKE predicates.
Option can be set at the database (PUBLIC) or user level. When set at the database level, the value becomes the default for any new user, but has no impact on existing users. When set at the user level, overrides the PUBLIC value for that user only. No system privilege is required to set option for self. System privilege is required to set at database level or at user level for any user other than self.
Requires the SET ANY PUBLIC OPTION system privilege to set this option. Can be set temporary for an individual connection or for the PUBLIC role. Takes effect immediately.
DEFAULT_LIKE_RANGE_SELECTIVITY_PPM sets the default selectivity for LIKE predicates, of the form LIKE 'string%' where the match string is a set of constant characters followed by a single wildcard character (%). The optimizer relies on this option when other selectivity information is not available.
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.