*This is my rule class*
public class CartesianProductJoinRule extends RelOptRule {
public static final CartesianProductJoinRule INSTANCE = new
CartesianProductJoinRule(DrillJoinRel.class);
public CartesianProductJoinRule(Class<DrillJoinRel> clazz) {
super(operand(clazz, operand(RelNode.class, any()),
operand(RelNode.class, any())),
"CartesianProductJoin");
}
@Override
public boolean matches(RelOptRuleCall call) {
DrillJoinRel drillJoin = call.rel(0);
return drillJoin.getJoinType() == JoinRelType.INNER &&
drillJoin.getCondition().isAlwaysTrue();
}
@Override
public void onMatch(RelOptRuleCall call) {
DrillJoinRel join = call.rel(0);
RelNode firstRel = call.rel(1);
RelNode secondRel = call.rel(2);
HepRelVertex right = (HepRelVertex) join.getRight();
HepRelVertex left = (HepRelVertex) join.getLeft();
List<RelDataTypeField> firstFields = firstRel.getRowType().
getFieldList();
List<RelDataTypeField> secondFields = secondRel.getRowType().
getFieldList();
RelNode firstTable = ((HepRelVertex)firstRel.
getInput(0)).getCurrentRel();
RelNode secondTable = ((HepRelVertex)secondRel.
getInput(0)).getCurrentRel();
//call.transformTo(???);
}
}
*To register the rule*, I overrode the *getOptimizerRules* method in my
storage plugin class
public Set<? extends RelOptRule> getOptimizerRules(OptimizerRulesContext
optimizerContext, PlannerPhase phase) {
switch (phase) {
case LOGICAL_PRUNE_AND_JOIN:
case LOGICAL_PRUNE:
case LOGICAL:
return getLogicalOptimizerRules(optimizerContext);
case PHYSICAL:
return getPhysicalOptimizerRules(optimizerContext);
case PARTITION_PRUNING:
case JOIN_PLANNING:
* return ImmutableSet.of(CartesianProductJoinRule.INSTANCE);*
default:
return ImmutableSet.of();
}
}
The rule is firing as expected but I'm lost when it comes to the
conversion. Earlier, you said "the new equivalent ScanRel is to have the joined
ScanRel nodes's GroupScans", so
1. How can I obtain the left and right tables group scans ?
2. What exactly do you mean by joining them ? Is there a utility method
to do so ? Or should I manually create a new single group scan and add the
information I need there ? Looking into other *GroupScan*
implementations, I found that they have references to some runtime objects
such as the storage plugin and the storage plugin configuration. At this
stage, I don't know how to obtain those !
3. Precisely, what kind of object should I use to represent a *RelNode*
that represents the whole join ? I understand that I need to use an object
that has implements the *RelNode* interface. Then I should add the
created *GroupScan* to that *RelNode* instance and call
*call.transformTo(newRelNode)*, correct ?
*---------------------*
*Muhammad Gelbana*
http://www.linkedin.com/in/mgelbana
On Thu, Mar 30, 2017 at 2:46 AM, weijie tong <tongweijie...@gmail.com>
wrote:
> I mean the rule you write could be placed in the PlannerPhase.JOIN_PlANNING
> which uses the HepPlanner. This phase is to solve the logical relnode .
> Hope to help you.
> Muhammad Gelbana <m.gelb...@gmail.com>于2017年3月30日 周四上午12:07写道：
>
> > Thanks a lot Weijie, I believe I'm very close now. I hope you don't mind
> > few more questions please:
> >
> >
> > 1. The new rule you are mentioning is a physical rule ? So I should
> > implement the Prel interface ?
> > 2. By "traversing the join to find the ScanRel"
> > - This sounds like I have to "search" for something. Shouldn't I
> just
> > work on transforming the left (i.e. DrillJoinRel's getLeft()
> method)
> > and
> > right (i.e. DrillJoinRel's getLeft() method) join objects ?
> > - The "left" and "right" elements of the DrillJoinRel object are of
> > type RelSubset, not *ScanRel* and I can't find a type called
> > *ScanRel*.
> > I suppose you meant *ScanPrel*, specially because it implements the
> > *Prel* interface that provides the *getPhysicalOperator* method.
> > 3. What if multiple physical or logical rules match for a single node,
> > what decides which rule will be applied and which will be rejected ?
> Is
> > it
> > the *AbstractRelNode.computeSelfCost(RelOptPlanner)* method ? What if
> > more than one rule produces the same cost ?
> >
> > I'll go ahead and see what I can do for now before hopefully you may
> offer
> > more guidance. THANKS A LOT.
> >
> > *---------------------*
> > *Muhammad Gelbana*
> > http://www.linkedin.com/in/mgelbana
> >
> > On Wed, Mar 29, 2017 at 4:23 AM, weijie tong <tongweijie...@gmail.com>
> > wrote:
> >
> > > to avoid misunderstanding , the new equivalent ScanRel is to have the
> > > joined ScanRel nodes's GroupScans, as the GroupScans indirectly hold
> the
> > > underlying storage information.
> > >
> > > On Wed, Mar 29, 2017 at 10:15 AM, weijie tong <tongweijie...@gmail.com
> >
> > > wrote:
> > >
> > > >
> > > > my suggestion is you define a rule which matches the DrillJoinRel
> > RelNode
> > > > , then at the onMatch method ,you traverse the join children to find
> > the
> > > > ScanRel nodes . You define a new ScanRel which include the ScanRel
> > nodes
> > > > you find last step. Then transform the JoinRel to this equivalent new
> > > > ScanRel.
> > > > Finally , the plan tree will not have the JoinRel but the ScanRel.
> > You
> > > > can let your join plan rule in the PlannerPhase.JOIN_PLANNING.
> > > >
> > >
> >
>
