Hi all,
I have a query joins three tables (star schema, T is the fact
table): "select * from R, S, T where R.key = T.key and S.key = T.key" and
want to use calcite to parse and generate the physical plan.
When I pass the query to a volcano planner, it throws the
CannotPlanException:
Exception in thread "main"
org.apache.calcite.plan.RelOptPlanner$CannotPlanException: There are not
enough rules to produce a node with desired properties:
convention=ENUMERABLE.
Missing conversions are LogicalJoin[convention: NONE -> JDBC.DB1] (2 cases)
There are 2 empty subsets:
Empty subset 0: rel#34:RelSubset#2.JDBC.DB1, the relevant part of the
original plan is as follows
14:LogicalJoin(condition=[true], joinType=[inner])
1:JdbcTableScan(subset=[rel#12:RelSubset#0.JDBC.DB1], table=[[DB1, R]])
3:JdbcTableScan(subset=[rel#13:RelSubset#1.JDBC.DB1], table=[[DB1, S]])
Empty subset 1: rel#36:RelSubset#4.JDBC.DB1, the relevant part of the
original plan is as follows
17:LogicalJoin(condition=[true], joinType=[inner])
14:LogicalJoin(subset=[rel#15:RelSubset#2.NONE], condition=[true],
joinType=[inner])
1:JdbcTableScan(subset=[rel#12:RelSubset#0.JDBC.DB1], table=[[DB1, R]])
3:JdbcTableScan(subset=[rel#13:RelSubset#1.JDBC.DB1], table=[[DB1, S]])
7:JdbcTableScan(subset=[rel#16:RelSubset#3.JDBC.DB1], table=[[DB1, T]])
I tried to rewrite the query, and found that as long as T is not the last
relation (e.g. "select * from T, R, S where R.key = T.key and S.key =
T.key"), there is no error. I think it means that the join order in the
initial logical plan makes the difference, so I tried to add the
JoinAssociateRule. However, I found this rule was not applied by the
optimizer because of the convocation not match. Using the above example,
for 17:LogicalJoin the convocation of 14:LogicalJoin and 7:JdbcTableScan
are not the same ( at here:
https://github.com/apache/calcite/blob/e42b85a45bd16dd58db1546736e653deda5463fe/core/src/main/java/org/apache/calcite/plan/volcano/VolcanoRuleCall.java#L358
).
These are the rules in the planner:
[FilterIntoJoinRule, JoinAssociateRule, JoinCommuteRule,
JdbcToEnumerableConverterRule(in:JDBC.DB1,out:ENUMERABLE),
JdbcJoinRule(in:NONE,out:JDBC.DB1), JdbcProjectRule(in:NONE,out:JDBC.DB1),
JdbcFilterRule(in:NONE,out:JDBC.DB1),
JdbcAggregateRule(in:NONE,out:JDBC.DB1),
JdbcSortRule(in:NONE,out:JDBC.DB1), JdbcUnionRule(in:NONE,out:JDBC.DB1),
JdbcIntersectRule(in:NONE,out:JDBC.DB1),
JdbcMinusRule(in:NONE,out:JDBC.DB1),
JdbcTableModificationRule(in:NONE,out:JDBC.DB1),
JdbcValuesRule(in:NONE,out:JDBC.DB1), FilterSetOpTransposeRule,
ProjectRemoveRule]
I'm very new to Calcite. I'm not sure whether I missed some rules or I have
to implement something to make it work. Can anyone help me on this?
Best,
Xiaoying
