[jira] [Work logged] (HIVE-25941) Long compilation time of complex query due to analysis for materialized view rewrite

["ASF GitHub Bot (Jira)" <ji...@apache.org>]

     [ https://issues.apache.org/jira/browse/HIVE-25941?focusedWorklogId=737775&page=com.atlassian.jira.plugin.system.issuetabpanels:worklog-tabpanel#worklog-737775 ]

ASF GitHub Bot logged work on HIVE-25941:
-----------------------------------------

                Author: ASF GitHub Bot
            Created on: 07/Mar/22 20:40
            Start Date: 07/Mar/22 20:40
    Worklog Time Spent: 10m 
      Work Description: amansinha100 commented on a change in pull request #3014:
URL: https://github.com/apache/hive/pull/3014#discussion_r821084834



##########
File path: ql/src/java/org/apache/hadoop/hive/ql/metadata/MaterializedViewsCache.java
##########
@@ -205,4 +212,52 @@ HiveRelOptMaterialization get(String dbName, String viewName) {
   public boolean isEmpty() {
     return materializedViews.isEmpty();
   }
+
+
+  private static class ASTKey {
+    private final ASTNode root;
+
+    public ASTKey(ASTNode root) {
+      this.root = root;
+    }
+
+    @Override
+    public boolean equals(Object o) {
+      if (this == o) return true;
+      if (o == null || getClass() != o.getClass()) return false;
+      ASTKey that = (ASTKey) o;
+      return equals(root, that.root);
+    }
+
+    private boolean equals(ASTNode astNode1, ASTNode astNode2) {
+      if (!(astNode1.getType() == astNode2.getType() &&
+              astNode1.getText().equals(astNode2.getText()) &&
+              astNode1.getChildCount() == astNode2.getChildCount())) {
+        return false;
+      }
+
+      for (int i = 0; i < astNode1.getChildCount(); ++i) {
+        if (!equals((ASTNode) astNode1.getChild(i), (ASTNode) astNode2.getChild(i))) {
+          return false;
+        }
+      }
+
+      return true;
+    }
+
+    @Override
+    public int hashCode() {
+      return hashcode(root);
+    }
+
+    private int hashcode(ASTNode node) {
+      int result = Objects.hash(node.getType(), node.getText());

Review comment:
       Sounds ok to do in a follow-up patch if there is a performance issue.  It would be useful to leave a comment in the code about possibly revisiting this if needed.  Also,  may want to mention about the mutability aspect of ASTNode since it means that caching the hash code is not an option if something changed in the lower levels of the AST. 




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Issue Time Tracking
-------------------

    Worklog Id:     (was: 737775)
    Time Spent: 50m  (was: 40m)

> Long compilation time of complex query due to analysis for materialized view rewrite
> ------------------------------------------------------------------------------------
>
>                 Key: HIVE-25941
>                 URL: https://issues.apache.org/jira/browse/HIVE-25941
>             Project: Hive
>          Issue Type: Bug
>          Components: Materialized views
>            Reporter: Krisztian Kasa
>            Assignee: Krisztian Kasa
>            Priority: Major
>              Labels: pull-request-available
>         Attachments: sample.png
>
>          Time Spent: 50m
>  Remaining Estimate: 0h
>
> When compiling query the optimizer tries to rewrite the query plan or subtrees of the plan to use materialized view scans.
> If
> {code}
> set hive.materializedview.rewriting.sql.subquery=false;
> {code}
> the compilation succeed in less then 10 sec otherwise it takes several minutes (~ 5min) depending on the hardware.



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