Provides default selectivity estimates to the optimizer for leading constant LIKE predicates.
0 to 100
15
Can be set for an individual connection or the PUBLIC group. Takes effect immediately.
DEFAULT_LIKE_RANGE_SELECTIVITY 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 a LF index or a 1- or 2-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, as described in “User-supplied condition hints”.
“DEFAULT_LIKE_MATCH_SELECTIVITY option”
Chapter 3, “Optimizing Queries and Deletions” in the Sybase IQ Performance and Tuning Guide
