// for projection
this.projector = new Projector(inSchema, outSchema, plan.getTargets());
// for join
frameTuple = new FrameTuple();
outTuple = new VTuple(outSchema.size());
leftKeyTuple = new VTuple(leftKeyList.length);
leftNumCols = outer.getSchema().size();
rightNumCols = inner.getSchema().size();