Provides default selectivity estimates to the optimizer for leading constant LIKE predicates.
0 to 100
Can be set for an individual connection or the PUBLIC group. Takes effect immediately.
15
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.
Note that 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 the section “User-supplied estimates” of the “Search conditions” section in Chapter 3, “SQL Language Elements.”
“DEFAULT_LIKE_MATCH_SELECTIVITY option”
“LIKE conditions” of the “Search conditions” section in Chapter 3, “SQL Language Elements”
Chapter 3, “Improving Query Performance” in the Sybase IQ Performance and Tuning Guide
