morrySnow commented on code in PR #12147:
URL: https://github.com/apache/doris/pull/12147#discussion_r957387267
##########
fe/fe-core/src/main/java/org/apache/doris/nereids/memo/Memo.java:
##########
@@ -277,12 +346,172 @@ public void addEnforcerPlan(GroupExpression
groupExpression, Group group) {
groupExpression.setOwnerGroup(group);
}
+ private CopyInResult rewriteByExistsPlan(Group targetGroup, Plan
existsPlan) {
+ GroupExpression existedLogicalExpression = existsPlan instanceof
GroupPlan
+ ? ((GroupPlan) existsPlan).getGroup().getLogicalExpression()
// get first logicalGroupExpression
+ : existsPlan.getGroupExpression().get();
+ if (targetGroup != null) {
+ Group existedGroup = existedLogicalExpression.getOwnerGroup();
+ // clear targetGroup, from exist group move all logical
groupExpression
+ // and logicalProperties to target group
+ eliminateFromGroupAndMoveToTargetGroup(existedGroup, targetGroup,
existsPlan.getLogicalProperties());
+ }
+ return CopyInResult.of(false, existedLogicalExpression);
+ }
+
+ private CopyInResult rewriteByNewGroupExpression(Group targetGroup, Plan
newPlan,
+ GroupExpression newGroupExpression) {
+ if (targetGroup == null) {
+ // case 2:
+ // if not exist target group and not exist the same group
expression,
+ // then create new group with the newGroupExpression
+ Group newGroup = new Group(groupIdGenerator.getNextId(),
newGroupExpression,
+ newPlan.getLogicalProperties());
+ groups.put(newGroup.getGroupId(), newGroup);
+ groupExpressions.put(newGroupExpression, newGroupExpression);
+ } else {
+ // case 3:
+ // if exist the target group, clear all origin group expressions
in the
+ // existedExpression's owner group and reset logical properties,
the
+ // newGroupExpression is the init logical group expression
+ reInitGroup(targetGroup, newGroupExpression,
newPlan.getLogicalProperties());
+ }
+ return CopyInResult.of(true, newGroupExpression);
+ }
+
+ private CopyInResult rewriteByExistedGroupExpression(Group targetGroup,
Plan existedPlan,
+ GroupExpression existedExpression, GroupExpression newExpression) {
+ if (targetGroup != null &&
!targetGroup.equals(existedExpression.getOwnerGroup())) {
+ // case 4:
+ existedExpression.propagateApplied(newExpression);
+ moveParentExpressionsReference(existedExpression.getOwnerGroup(),
targetGroup);
+ recycleGroup(existedExpression.getOwnerGroup());
+ reInitGroup(targetGroup, newExpression,
existedPlan.getLogicalProperties());
+ return CopyInResult.of(true, newExpression);
+ } else {
+ // case 5:
+ // if targetGroup is null or targetGroup equal to the
existedExpression's ownerGroup,
+ // then recycle the temporary new group expression
+ recycleExpression(newExpression);
+ return CopyInResult.of(false, existedExpression);
+ }
+ }
+
+ /**
+ * eliminate fromGroup, clear targetGroup, then move the logical group
expressions in the fromGroup to the toGroup.
+ *
+ * the scenario is:
+ * ```
+ * Group 1(project, the targetGroup) Group
1(logicalOlapScan, the targetGroup)
+ * | =>
+ * Group 0(logicalOlapScan, the fromGroup)
+ * ```
+ *
+ * we should recycle the group 0, and recycle all group expressions in
group 1, then move the logicalOlapScan to
+ * the group 1, and reset logical properties of the group 1.
+ */
+ private void eliminateFromGroupAndMoveToTargetGroup(Group fromGroup, Group
targetGroup,
+ LogicalProperties logicalProperties) {
+ if (fromGroup == targetGroup) {
+ return;
+ }
+ // simple check targetGroup is the ancestors of the fromGroup, not
check completely because of performance
+ if (fromGroup == root) {
+ throw new IllegalStateException(
+ "TargetGroup should be ancestors of fromGroup, but
fromGroup is root. Maybe a bug");
+ }
+
+ List<GroupExpression> logicalExpressions =
fromGroup.clearLogicalExpressions();
+ recycleGroup(fromGroup);
+
+ recycleLogicalExpressions(targetGroup);
+ recyclePhysicalExpressions(targetGroup);
+
+ for (GroupExpression logicalExpression : logicalExpressions) {
+ targetGroup.addLogicalExpression(logicalExpression);
+ }
+ targetGroup.setLogicalProperties(logicalProperties);
+ }
+
+ private void reInitGroup(Group group, GroupExpression
initLogicalExpression, LogicalProperties logicalProperties) {
+ recycleLogicalExpressions(group);
+ recyclePhysicalExpressions(group);
+
+ group.setLogicalProperties(logicalProperties);
+ group.addLogicalExpression(initLogicalExpression);
+
+ // note: put newGroupExpression must behind recycle
existedExpression(reInitGroup method),
+ // because existedExpression maybe equal to the
newGroupExpression and recycle
+ // existedExpression will recycle newGroupExpression
+ groupExpressions.put(initLogicalExpression, initLogicalExpression);
+ }
+
private Plan replaceChildrenToGroupPlan(Plan plan, List<Group>
childrenGroups) {
+ if (childrenGroups.isEmpty()) {
+ return plan;
+ }
List<Plan> groupPlanChildren = childrenGroups.stream()
.map(GroupPlan::new)
.collect(ImmutableList.toImmutableList());
LogicalProperties logicalProperties = plan.getLogicalProperties();
return plan.withChildren(groupPlanChildren)
.withLogicalProperties(Optional.of(logicalProperties));
}
+
+ private void moveParentExpressionsReference(Group fromGroup, Group
toGroup) {
+ for (GroupExpression parentGroupExpression :
fromGroup.getParentGroupExpressions()) {
+ /*
+ * the scenarios that 'parentGroupExpression == toGroup':
eliminate the root group.
+ * the fromGroup is group 1, the toGroup is group 2, we can not
replace group2's
+ * groupExpressions reference the child group which is group 2
(reference itself).
+ *
+ * A(group 2) B(group 2)
+ * | |
+ * B(group 1) => C(group 0)
+ * |
+ * C(group 0)
+ */
+ if (parentGroupExpression.getOwnerGroup() != toGroup) {
+ parentGroupExpression.replaceChild(fromGroup, toGroup);
Review Comment:
if we do this separately, we need to add more comment to explain it.
Otherwise this method may be used by mistake
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