// ScopeCoalesce needed
// Scope is:
// new ScopeRename(oldScope, renames) ;
// And ScopeBase ==> ScopeTable.
idScope = new ScopeRename(join.getIdScope()) ;
nodeScope = new ScopeRename(join.getNodeScope()) ;
SqlTable table = new SqlTable(alias) ;
nonCoalesceVars = SetUtils.difference(join.getIdScope().getVars(),
coalesceVars) ;