[GitHub] [doris] morrySnow commented on a diff in pull request #20746: [feature](Nereids) add cbo rewrite framework

["morrySnow (via GitHub)" <gi...@apache.org>]

morrySnow commented on code in PR #20746:
URL: https://github.com/apache/doris/pull/20746#discussion_r1228901030


##########
fe/fe-core/src/main/java/org/apache/doris/nereids/jobs/rewrite/CostBasedRewriteJob.java:
##########
@@ -0,0 +1,90 @@
+// Licensed to the Apache Software Foundation (ASF) under one
+// or more contributor license agreements.  See the NOTICE file
+// distributed with this work for additional information
+// regarding copyright ownership.  The ASF licenses this file
+// to you under the Apache License, Version 2.0 (the
+// "License"); you may not use this file except in compliance
+// with the License.  You may obtain a copy of the License at
+//
+//   http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing,
+// software distributed under the License is distributed on an
+// "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
+// KIND, either express or implied.  See the License for the
+// specific language governing permissions and limitations
+// under the License.
+
+package org.apache.doris.nereids.jobs.rewrite;
+
+import org.apache.doris.common.Pair;
+import org.apache.doris.nereids.CascadesContext;
+import org.apache.doris.nereids.cost.Cost;
+import org.apache.doris.nereids.jobs.JobContext;
+import org.apache.doris.nereids.jobs.executor.Optimizer;
+import org.apache.doris.nereids.jobs.executor.Rewriter;
+import org.apache.doris.nereids.memo.GroupExpression;
+import org.apache.doris.nereids.properties.PhysicalProperties;
+
+import com.google.common.collect.ImmutableList;
+
+import java.util.List;
+import java.util.Optional;
+
+/**
+ * Cost based rewrite job.
+ * This job do
+ */
+public class CostBasedRewriteJob implements RewriteJob {
+
+    private final List<RewriteJob> rewriteJobs;
+
+    public CostBasedRewriteJob(List<RewriteJob> rewriteJobs) {
+        this.rewriteJobs = rewriteJobs;
+        // need to generate real rewrite job list
+    }
+
+    @Override
+    public void execute(JobContext jobContext) {
+        CascadesContext cascadesContext = jobContext.getCascadesContext();
+        CascadesContext skipCboRuleCtx = CascadesContext.newRewriteContext(
+                cascadesContext, cascadesContext.getRewritePlan(),
+                cascadesContext.getCurrentJobContext().getRequiredProperties());
+        CascadesContext applyCboRuleCtx = CascadesContext.newRewriteContext(
+                cascadesContext, cascadesContext.getRewritePlan(),
+                cascadesContext.getCurrentJobContext().getRequiredProperties());
+
+        // Do rewrite on 2 candidates
+        List<RewriteJob> withCboJobs = ImmutableList.<RewriteJob>builder()
+                .addAll(rewriteJobs)
+                .addAll(jobContext.getRemainJobs())
+                .build();
+        new Rewriter(skipCboRuleCtx, jobContext.getRemainJobs()).execute();
+        new Rewriter(applyCboRuleCtx, withCboJobs).execute();
+        if (skipCboRuleCtx.getRewritePlan().deepEquals(applyCboRuleCtx.getRewritePlan())) {
+            // this means rewrite do not do anything
+            return;
+        }
+        // Do optimize on 2 candidates
+        new Optimizer(skipCboRuleCtx).execute();
+        new Optimizer(applyCboRuleCtx).execute();
+        Optional<Pair<Cost, GroupExpression>> skipCboRuleCost = skipCboRuleCtx.getMemo().getRoot()
+                .getLowestCostPlan(PhysicalProperties.GATHER);
+        Optional<Pair<Cost, GroupExpression>> appliedCboRuleCost = applyCboRuleCtx.getMemo().getRoot()
+                .getLowestCostPlan(PhysicalProperties.GATHER);
+        // If one of them optimize failed, just return
+        if (!skipCboRuleCost.isPresent() || !appliedCboRuleCost.isPresent()) {
+            return;

Review Comment:
   right, wo should do some log here



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