diff --git a/processing/src/main/java/org/apache/druid/query/aggregation/last/StringLastBufferAggregator.java b/processing/src/main/java/org/apache/druid/query/aggregation/last/StringLastBufferAggregator.java
index 8611ef72365..3f78745f5fa 100644
--- a/processing/src/main/java/org/apache/druid/query/aggregation/last/StringLastBufferAggregator.java
+++ b/processing/src/main/java/org/apache/druid/query/aggregation/last/StringLastBufferAggregator.java
@@ -64,9 +64,6 @@ public class StringLastBufferAggregator implements BufferAggregator
   @Override
   public void aggregate(ByteBuffer buf, int position)
   {
-    if (timeSelector.isNull()) {
-      return;
-    }
     if (needsFoldCheck) {
       // Less efficient code path when folding is a possibility (we must read the value selector first just in case
       // it's a foldable object).
@@ -87,6 +84,9 @@ public class StringLastBufferAggregator implements BufferAggregator
         }
       }
     } else {
+      if (timeSelector.isNull()) {
+        return;
+      }
       final long time = timeSelector.getLong();
       final long lastTime = buf.getLong(position);
 
diff --git a/sql/src/main/java/org/apache/druid/sql/calcite/planner/CalciteRulesManager.java b/sql/src/main/java/org/apache/druid/sql/calcite/planner/CalciteRulesManager.java
index 5bf4bee733c..2e5a79d6a7c 100644
--- a/sql/src/main/java/org/apache/druid/sql/calcite/planner/CalciteRulesManager.java
+++ b/sql/src/main/java/org/apache/druid/sql/calcite/planner/CalciteRulesManager.java
@@ -260,7 +260,10 @@ public class CalciteRulesManager
 
     boolean isDebug = plannerContext.queryContext().isDebug();
     return ImmutableList.of(
-        Programs.sequence(preProgram, Programs.ofRules(druidConventionRuleSet(plannerContext))),
+        Programs.sequence(preProgram,
+            new LoggingProgram("Start", true),
+            Programs.ofRules(druidConventionRuleSet(plannerContext)),
+            new LoggingProgram("End", true)),
         Programs.sequence(preProgram, Programs.ofRules(bindableConventionRuleSet(plannerContext))),
         Programs.sequence(
             // currently, adding logging program after every stage for easier debugging