DEFAULT_LIKE_MATCH_SELECTIVITY_PPM Option

Provides default selectivity estimates (in parts per million) to the optimizer for most LIKE predicates.

Allowed Values

0 to 1000000

Default

150000

Scope

Can be set for an individual connection or the PUBLIC group. Takes effect immediately.

Description

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.

Related reference
DEFAULT_LIKE_RANGE_SELECTIVITY_PPM Option
FP_LOOKUP_SIZE Option