[GitHub] [druid] himanshug commented on a change in pull request #9634: More optimize CNF conversion of filters

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himanshug commented on a change in pull request #9634: More optimize CNF conversion of filters
URL: https://github.com/apache/druid/pull/9634#discussion_r405769028
 
 

 ##########
 File path: processing/src/main/java/org/apache/druid/segment/filter/Filters.java
 ##########
 @@ -426,175 +424,21 @@ public static Filter convertToCNFFromQueryContext(Query query, @Nullable Filter
       return null;
     }
     boolean useCNF = query.getContextBoolean(CTX_KEY_USE_FILTER_CNF, false);
-    return useCNF ? toCNF(filter) : filter;
+    return useCNF ? Filters.toCnf(filter) : filter;
   }
 
-  public static Filter toCNF(Filter current)
+  public static Filter toCnf(Filter current)
   {
-    current = pushDownNot(current);
-    current = flatten(current);
-    current = convertToCNFInternal(current);
-    current = flatten(current);
+    current = HiveCnfHelper.pushDownNot(current);
+    current = HiveCnfHelper.flatten(current);
+    // Pull out AND filters first to convert the filter into a conjunctive form.
+    // This is important to not create a huge CNF.
+    current = CalciteCnfHelper.pull(current);
+    current = HiveCnfHelper.convertToCNFInternal(current);
+    current = HiveCnfHelper.flatten(current);
 
 Review comment:
   It would be nice to add some commentary on each line describing (possibly with example) why it exists. I know there is something in PR description but this is non-trivial.

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