diff --git a/integ-test/src/yamlRestTest/resources/rest-api-spec/test/issues/4529.yml b/integ-test/src/yamlRestTest/resources/rest-api-spec/test/issues/4529.yml
new file mode 100644
index 00000000000..ad7e78c6c8e
--- /dev/null
+++ b/integ-test/src/yamlRestTest/resources/rest-api-spec/test/issues/4529.yml
@@ -0,0 +1,46 @@
+setup:
+  - do:
+      query.settings:
+        body:
+          transient:
+            plugins.calcite.enabled : true
+  - do:
+      bulk:
+        index: test
+        refresh: true
+        body:
+          - '{"index": {}}'
+          - '{"category":"A","has_flag":true,"value":10}'
+          - '{"index": {}}'
+          - '{"category":"B","has_flag":true,"value":20}'
+          - '{"index": {}}'
+          - '{"category":"C","has_flag":true,"value":30}'
+          - '{"index": {}}'
+          - '{"category":"D","has_flag":false,"value":40}'
+          - '{"index": {}}'
+          - '{"category":"E","has_flag":false,"value":50}'
+          - '{"index": {}}'
+          - '{"category":"F","has_flag":false,"value":60}'
+
+---
+teardown:
+  - do:
+      query.settings:
+        body:
+          transient:
+            plugins.calcite.enabled : false
+
+---
+"Join with fields":
+  - skip:
+      features:
+        - headers
+        - allowed_warnings
+  - do:
+      headers:
+        Content-Type: 'application/json'
+      ppl:
+        body:
+          query: source=test | stats COUNT() as cnt by category, has_flag | fields category, has_flag, cnt | join left=L right=R ON L.has_flag = R.has_flag [source=test | stats COUNT() as overall_cnt by has_flag]
+
+  - match: { total: 6 }
diff --git a/opensearch/src/main/java/org/opensearch/sql/opensearch/planner/physical/OpenSearchSortIndexScanRule.java b/opensearch/src/main/java/org/opensearch/sql/opensearch/planner/physical/OpenSearchSortIndexScanRule.java
index b95725c3e16..47274f467fc 100644
--- a/opensearch/src/main/java/org/opensearch/sql/opensearch/planner/physical/OpenSearchSortIndexScanRule.java
+++ b/opensearch/src/main/java/org/opensearch/sql/opensearch/planner/physical/OpenSearchSortIndexScanRule.java
@@ -23,6 +23,9 @@ protected OpenSearchSortIndexScanRule(Config config) {
   public void onMatch(RelOptRuleCall call) {
     final Sort sort = call.rel(0);
     final AbstractCalciteIndexScan scan = call.rel(1);
+    if (sort.getConvention() != scan.getConvention()) {
+      return;
+    }
 
     var collations = sort.collation.getFieldCollations();
     AbstractCalciteIndexScan newScan = scan.pushDownSort(collations);
diff --git a/opensearch/src/main/java/org/opensearch/sql/opensearch/request/AggregateAnalyzer.java b/opensearch/src/main/java/org/opensearch/sql/opensearch/request/AggregateAnalyzer.java
index 350b9e37926..99d4c9eb235 100644
--- a/opensearch/src/main/java/org/opensearch/sql/opensearch/request/AggregateAnalyzer.java
+++ b/opensearch/src/main/java/org/opensearch/sql/opensearch/request/AggregateAnalyzer.java
@@ -380,6 +380,8 @@ private static Pair<AggregationBuilder, MetricParser> createRegularAggregation(
       case AVG -> Pair.of(
           helper.build(args.getFirst(), AggregationBuilders.avg(aggFieldName)),
           new SingleValueParser(aggFieldName));
+        // 1. Only case SUM, skip SUM0 / COUNT since calling avg() in DSL should be faster.
+        // 2. To align with databases, SUM0 is not preferred now.
       case SUM -> Pair.of(
           helper.build(args.getFirst(), AggregationBuilders.sum(aggFieldName)),
           new SingleValueParser(aggFieldName));
diff --git a/opensearch/src/main/java/org/opensearch/sql/opensearch/storage/scan/AbstractCalciteIndexScan.java b/opensearch/src/main/java/org/opensearch/sql/opensearch/storage/scan/AbstractCalciteIndexScan.java
index d935ea7029e..ad02a898128 100644
--- a/opensearch/src/main/java/org/opensearch/sql/opensearch/storage/scan/AbstractCalciteIndexScan.java
+++ b/opensearch/src/main/java/org/opensearch/sql/opensearch/storage/scan/AbstractCalciteIndexScan.java
@@ -258,20 +258,8 @@ public AbstractCalciteIndexScan pushDownSort(List<RelFieldCollation> collations)
         // aggregators.
         return null;
       }
-
-      // Propagate the sort to the new scan
       RelTraitSet traitsWithCollations = getTraitSet().plus(RelCollations.of(collations));
-      AbstractCalciteIndexScan newScan =
-          buildScan(
-              getCluster(),
-              traitsWithCollations,
-              hints,
-              table,
-              osIndex,
-              getRowType(),
-              // Existing collations are overridden (discarded) by the new collations,
-              pushDownContext.cloneWithoutSort());
-
+      PushDownContext pushDownContextWithoutSort = this.pushDownContext.cloneWithoutSort();
       AbstractAction<?> action;
       Object digest;
       if (pushDownContext.isAggregatePushed()) {
@@ -281,7 +269,27 @@ public AbstractCalciteIndexScan pushDownSort(List<RelFieldCollation> collations)
                 aggAction ->
                     aggAction.pushDownSortIntoAggBucket(collations, getRowType().getFieldNames());
         digest = collations;
+        pushDownContextWithoutSort.add(PushDownType.SORT, digest, action);
+        return buildScan(
+            getCluster(),
+            traitsWithCollations,
+            hints,
+            table,
+            osIndex,
+            getRowType(),
+            pushDownContextWithoutSort.clone());
       } else {
+        // Propagate the sort to the new scan
+        AbstractCalciteIndexScan newScan =
+            buildScan(
+                getCluster(),
+                traitsWithCollations,
+                hints,
+                table,
+                osIndex,
+                getRowType(),
+                // Existing collations are overridden (discarded) by the new collations,
+                pushDownContextWithoutSort);
         List<SortBuilder<?>> builders = new ArrayList<>();
         for (RelFieldCollation collation : collations) {
           int index = collation.getFieldIndex();
@@ -310,9 +318,9 @@ public AbstractCalciteIndexScan pushDownSort(List<RelFieldCollation> collations)
         }
         action = (OSRequestBuilderAction) requestBuilder -> requestBuilder.pushDownSort(builders);
         digest = builders.toString();
+        newScan.pushDownContext.add(PushDownType.SORT, digest, action);
+        return newScan;
       }
-      newScan.pushDownContext.add(PushDownType.SORT, digest, action);
-      return newScan;
     } catch (Exception e) {
       if (LOG.isDebugEnabled()) {
         LOG.debug("Cannot pushdown the sort {}", getCollationNames(collations), e);