Revert "Route pushDownSort count through LIMIT > k validation"

This reverts commit e0564e0.

Author: mengweieric

opensearch/src/main/java/org/opensearch/sql/opensearch/storage/scan/VectorSearchQueryBuilder.java

@@ -89,7 +89,13 @@ public boolean pushDownFilter(LogicalFilter filter) {
 
   @Override
   public boolean pushDownLimit(LogicalLimit limit) {
-    validateLimitWithinK(limit.getLimit());
+    if (options.containsKey("k")) {
+      int k = Integer.parseInt(options.get("k"));
+      if (limit.getLimit() > k) {
+        throw new ExpressionEvaluationException(
+            String.format("LIMIT %d exceeds k=%d in top-k vector search", limit.getLimit(), k));
+      }
+    }
     limitPushed = true;
     return super.pushDownLimit(limit);
   }
@@ -117,23 +123,11 @@ public boolean pushDownSort(LogicalSort sort) {
     // Preserve the parent's sort.getCount() → limit pushdown contract: SQL always sets count=0,
     // but PPL or future callers may set a non-zero count to combine sort+limit in one node.
     if (sort.getCount() != 0) {
-      validateLimitWithinK(sort.getCount());
       requestBuilder.pushDownLimit(sort.getCount(), 0);
     }
     return true;
   }
 
-  /** Validates that the requested limit does not exceed k in top-k mode. */
-  private void validateLimitWithinK(int limit) {
-    if (options.containsKey("k")) {
-      int k = Integer.parseInt(options.get("k"));
-      if (limit > k) {
-        throw new ExpressionEvaluationException(
-            String.format("LIMIT %d exceeds k=%d in top-k vector search", limit, k));
-      }
-    }
-  }
-
   @Override
   public OpenSearchRequestBuilder build() {
     if (filterTypeExplicit && !filterPushed) {

opensearch/src/test/java/org/opensearch/sql/opensearch/storage/scan/VectorSearchQueryBuilderTest.java

@@ -183,28 +183,6 @@ void pushDownSortPreservesSortCountAsLimit() {
         "sort.getCount() should be pushed down as request size");
   }
 
-  @Test
-  void pushDownSortCountExceedingKRejects() {
-    var requestBuilder = createRequestBuilder();
-    var knnQuery = new WrapperQueryBuilder("{\"knn\":{}}");
-    var builder = new VectorSearchQueryBuilder(requestBuilder, knnQuery, Map.of("k", "5"));
-
-    var dummyChild = new LogicalValues(Collections.emptyList());
-    // LogicalSort with count=10 exceeds k=5 — should be rejected
-    var sort =
-        new org.opensearch.sql.planner.logical.LogicalSort(
-            dummyChild,
-            10,
-            List.of(
-                org.apache.commons.lang3.tuple.ImmutablePair.of(
-                    org.opensearch.sql.ast.tree.Sort.SortOption.DEFAULT_DESC,
-                    new ReferenceExpression("_score", ExprCoreType.FLOAT))));
-
-    ExpressionEvaluationException ex =
-        assertThrows(ExpressionEvaluationException.class, () -> builder.pushDownSort(sort));
-    assertTrue(ex.getMessage().contains("LIMIT 10 exceeds k=5"));
-  }
-
   @Test
   void pushDownSortNonScoreFieldRejected() {
     var requestBuilder = createRequestBuilder();