/**
* Combines the join filters from the left and right inputs (if they are MultiJoinRels) with the
* join filter in the joinrel into a single AND'd join filter, unless the inputs correspond to
* null generating inputs in an outer join
*
* @param joinRel join rel
* @param left left child of the joinrel
* @param right right child of the joinrel
* @return combined join filters AND'd together
*/
private RexNode combineJoinFilters(JoinRel joinRel, RelNode left, RelNode right) {
RexBuilder rexBuilder = joinRel.getCluster().getRexBuilder();
JoinRelType joinType = joinRel.getJoinType();
// first need to adjust the RexInputs of the right child, since
// those need to shift over to the right
RexNode rightFilter = null;
if (canCombine(right, joinType.generatesNullsOnRight())) {
MultiJoinRel multiJoin = (MultiJoinRel) right;
rightFilter = shiftRightFilter(joinRel, left, multiJoin, multiJoin.getJoinFilter());
}
// AND the join condition if this isn't a left or right outer join;
// in those cases, the outer join condition is already tracked
// separately
RexNode newFilter = null;
if ((joinType != JoinRelType.LEFT) && (joinType != JoinRelType.RIGHT)) {
newFilter = joinRel.getCondition();
}
if (canCombine(left, joinType.generatesNullsOnLeft())) {
RexNode leftFilter = ((MultiJoinRel) left).getJoinFilter();
newFilter = RelOptUtil.andJoinFilters(rexBuilder, newFilter, leftFilter);
}
newFilter = RelOptUtil.andJoinFilters(rexBuilder, newFilter, rightFilter);
return newFilter;
}
// implement RelOptRule
public void onMatch(RelOptRuleCall call) {
FilterRel filterRel = call.rel(0);
MultiJoinRel multiJoinRel = call.rel(1);
MultiJoinRel newMultiJoinRel =
new MultiJoinRel(
multiJoinRel.getCluster(),
multiJoinRel.getInputs(),
multiJoinRel.getJoinFilter(),
multiJoinRel.getRowType(),
multiJoinRel.isFullOuterJoin(),
multiJoinRel.getOuterJoinConditions(),
multiJoinRel.getJoinTypes(),
multiJoinRel.getProjFields(),
multiJoinRel.getJoinFieldRefCountsMap(),
filterRel.getCondition());
call.transformTo(newMultiJoinRel);
}