9b91f86c38
Try to eliminate cross join via finding join conditions in filters and changing the join orders.
For example:
-- input:
SELECT * FROM t1, t2, t3 WHERE t1.id=t3.id AND t2.id=t3.id
-- output:
SELECT * FROM t1 JOIN t3 ON t1.id=t3.id JOIN t2 ON t2.id=t3.id
This feature is controlled by session variable enable_nereids_reorder_to_eliminate_cross_join with true by default.
Simplify usage of Memo and rewrite rule application.
Before this PR, if we want to apply a rewrite rule to a plan, the code is like the below:
Memo memo = new Memo();
memo.initialize(root);
PlannerContext plannerContext = new PlannerContext(memo, new ConnectContext());
JobContext jobContext = new JobContext(plannerContext, new PhysicalProperties(), 0);
RewriteTopDownJob rewriteTopDownJob = new RewriteTopDownJob(memo.getRoot(),
ImmutableList.of(new AggregateDisassemble().build()), jobContext);
plannerContext.pushJob(rewriteTopDownJob);
plannerContext.getJobScheduler().executeJobPool(plannerContext);
Plan after = memo.copyOut();
After this PR, we could use chain style calling:
new Memo(plan)
.newPlannerContext(connectContext)
.setDefaultJobContext()
.topDownRewrite(new AggregateDisassemble())
.getMemo()
.copyOut();
Rename the session variable enable_nereids to enable_nereids_planner to make it more meaningful.
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