WHERE clause costing causes WHINIT to use a heuristic to determine (among other things)
what indexes
to use to evaluate the WHERE clause. When WHERE clause costing is disabled by specifying
NOWHERECOSTING, WHINIT uses a rules-based evaluation that includes all available indexes
to evaluate the WHERE clause. The default setting enables users to use the SPDSWCST
macro variable to control whether WHERE clause costing or WHINIT is used. When NOWHERECOSTING is
set, the SPDSWCST macro variable has no effect.