[GitHub] [hive] jfsii commented on a diff in pull request #3487: HIVE-26438: Remove unnecessary optimization in canHandleQbForCbo()

[GitBox <gi...@apache.org>]

jfsii commented on code in PR #3487:
URL: https://github.com/apache/hive/pull/3487#discussion_r933840592


##########
ql/src/java/org/apache/hadoop/hive/ql/parse/CalcitePlanner.java:
##########
@@ -987,30 +985,29 @@ private static String canHandleQbForCbo(QueryProperties queryProperties, HiveCon
 
     // Not ok to run CBO, build error message.
     String msg = "";
-    if (verbose) {
-      if (queryProperties.hasClusterBy()) {
-        msg += "has cluster by; ";
-      }
-      if (queryProperties.hasDistributeBy()) {
-        msg += "has distribute by; ";
-      }
-      if (queryProperties.hasSortBy() && queryProperties.hasLimit()) {
-        msg += "has sort by with limit; ";
-      }
-      if (queryProperties.hasPTF()) {
-        msg += "has PTF; ";
-      }
-      if (queryProperties.usesScript()) {
-        msg += "uses scripts; ";
-      }
-      if (queryProperties.hasLateralViews()) {
-        msg += "has lateral views; ";
-      }
-      if (msg.isEmpty()) {
-        msg += "has some unspecified limitations; ";
-      }
-      msg = msg.substring(0, msg.length() - 2);
+    if (queryProperties.hasClusterBy()) {
+      msg += "has cluster by; ";
+    }
+    if (queryProperties.hasDistributeBy()) {
+      msg += "has distribute by; ";
+    }
+    if (queryProperties.hasSortBy() && queryProperties.hasLimit()) {
+      msg += "has sort by with limit; ";
+    }
+    if (queryProperties.hasPTF()) {
+      msg += "has PTF; ";
     }
+    if (queryProperties.usesScript()) {
+      msg += "uses scripts; ";
+    }
+    if (queryProperties.hasLateralViews()) {
+      msg += "has lateral views; ";
+    }
+    if (msg.isEmpty()) {
+    msg += "has some unspecified limitations; ";

Review Comment:
   indenting is incorrect  -
   one positive change from my suggestions above is that it enforces anyone who modifies this section of code with new conditions - would be forced to also provide a valid error message (so the only time msgs/reason would/should be empty is if it is a valid QB for  CBO).



##########
ql/src/java/org/apache/hadoop/hive/ql/parse/CalcitePlanner.java:
##########
@@ -987,30 +985,29 @@ private static String canHandleQbForCbo(QueryProperties queryProperties, HiveCon
 
     // Not ok to run CBO, build error message.
     String msg = "";
-    if (verbose) {
-      if (queryProperties.hasClusterBy()) {
-        msg += "has cluster by; ";
-      }
-      if (queryProperties.hasDistributeBy()) {
-        msg += "has distribute by; ";
-      }
-      if (queryProperties.hasSortBy() && queryProperties.hasLimit()) {
-        msg += "has sort by with limit; ";
-      }
-      if (queryProperties.hasPTF()) {
-        msg += "has PTF; ";
-      }
-      if (queryProperties.usesScript()) {
-        msg += "uses scripts; ";
-      }
-      if (queryProperties.hasLateralViews()) {
-        msg += "has lateral views; ";
-      }
-      if (msg.isEmpty()) {
-        msg += "has some unspecified limitations; ";
-      }
-      msg = msg.substring(0, msg.length() - 2);
+    if (queryProperties.hasClusterBy()) {

Review Comment:
   I would maybe change this to something like (but this is more of an opinion):
   List<String> reasons = new ArrayList();
   and in each if () { reason.add(errorMsg); }
   and at the end do:
   return Strings.join("; ", reasons);
   
   You could technically combine the top if check for validity with the error message processing to force each case to always have a valid error message by deleting the top if (conditions) { return null },
   add the missing condition to the error messages (queryProperties.isCBOSupportedLateralViews())) and change the last return to be something like:
   return reasons.isEmpty() ? null : Strings.join("; ",  reasons);
   
   Hopefully that makes sense? It is also a matter of style - feel free to ignore if you do not think the above suggestions make the code more readable or less fragile. (I'm not 100% sure they make it better - but in my head I think they do).



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