Set a proper type for string literals on ConstantColumn ctor
to fix the regression produced by MCOL-174.
Removed OPTIMIZER_SWITCH_EXISTS_TO_IN b/c MDB produces
unsupported optimization with it and CS couldn't create
ExistsFilter.
to avoid accedental crashes.
Add check for Conversion of Big IN Predicates Into Subqueries optimization
conditions.
Enabled derivedTableOptimization() for group by and derived handlers.
Disabled Conversion of Big IN Predicates Into Subqueries optimization.
Disabled most of optimizer_flags for now.
RowGroup + operator now correctly sets useStringTable flag that
instructs code to check StringStore instead of plain data buffer.
Renamed isInfiniDB() into isMCSTable
Changed getSelectPlan() to reuse it with derived and
other handler types.
Separate pushdown handlers methods and functions.
Removed vcxproj files from the source.
Added fix for MCOL-2166.
Merged with MCOL-2121
