SH query execution migrated from SH::init() into create_SH().
There is a session variable columnstore_processing_handlers_fallback
that allows to fallback to DH, GBH if SH fails. DH now uses semantic
tree check for unsupported features to allow to fallback to GBH or
storage API.
Fixes GBH related bug when create_GBH() returns a handler for
queries with impossible WHERE/HAVING.
Fixed bug in FromSubquery::transform() where isUnion is set to true.
Enabled RTTI b/c server team enabled it for MDB.
Removed unused code supposed to be used with vtable.
Fix crash in ha_calpont_impl_close_connection()
Fix leak in ci.tableMap.
Removed extra returns in pushdown_init to avoid crashes.
create_select_handler now detects INSERT..SELECT.
buildConstColFromFilter now uses any kind of filter to supply
relevant columns.
Remove strings used by vtable redo phase.
Make FromSubQuery aware of Pushdown handlers.
Changed debug_walk to work around changed Item framework.
Temporary disabled derived handler and unsupported features checks.
A view calling a view as part of a subquery outer join was not getting
the view name for the derived table columns. Which caused ColumnStore to
think it was joining outside of the view and triggered a missing column
error.
This fix adds the view name from the subquery if one cannot be obtained
from the field object.
