feat: add Hooks.AFTER_OPTIMIZATION

Author: kramerul

build.sh

@@ -31,7 +31,7 @@ VERSION=1.39.0
 
 for module in linq4j core;
 do
-  ./gradlew :${module}:clean :${module}:publishToMavenLocal
+  ./gradlew :${module}:clean -x :core:javadoc :${module}:publishToMavenLocal
    mvn install:install-file \
       -Dfile=${module}/build/libs/calcite-${module}-$VERSION-SNAPSHOT.jar \
       -DgroupId=org.apache.calcite \

core/src/main/java/org/apache/calcite/plan/volcano/VolcanoPlanner.java

@@ -91,6 +91,8 @@
 
 import static java.util.Objects.requireNonNull;
 
+import static org.apache.calcite.runtime.Hook.AFTER_OPTIMIZATION;
+
 /**
  * VolcanoPlanner optimizes queries by transforming expressions selectively
  * according to a dynamic programming algorithm.
@@ -533,6 +535,7 @@ protected void registerMaterializations() {
       LOGGER.info(sw.toString());
     }
     dumpRuleAttemptsInfo();
+    AFTER_OPTIMIZATION.run(root);
     RelNode cheapest = root.buildCheapestPlan(this);
     if (LOGGER.isDebugEnabled()) {
       LOGGER.debug(

core/src/main/java/org/apache/calcite/runtime/Hook.java

@@ -88,6 +88,9 @@ public enum Hook {
   /** Called to create a Program to optimize the statement. */
   PROGRAM,
 
+  /** Called to create a Program to optimize the statement. */
+  AFTER_OPTIMIZATION,
+
   /** Called when materialization is created. */
   CREATE_MATERIALIZATION,