[BACKPORT] [#6766] YCQL: Fix JSONB operator execution when applying t…

…o NULL objects

Summary: Back port to 2.2

Test Plan: TestJson and TestJsonIndex

Differential Revision: https://phabricator.dev.yugabyte.com/D10243

java/yb-cql/src/test/java/org/yb/cql/TestJson.java

@@ -97,7 +97,10 @@ public void testJson() throws Exception {
     session.execute("INSERT INTO test_json(c1, c2) values (6, 'null');");
     session.execute("INSERT INTO test_json(c1, c2) values (7, '2.0');");
     session.execute("INSERT INTO test_json(c1, c2) values (8, '{\"b\" : 1}');");
-    verifyResultSet(session.execute("SELECT * FROM test_json WHERE c1 = 1"));
+    // SELECT and verify JSONB column content.
+    verifyResultSet(session.execute("SELECT * FROM test_json WHERE c1 = 1;"));
+    // Apply JSONB operators to NULL and singular objects.
+    verifyEmptyRows(session.execute("SELECT c2->>'non_existing_value' FROM test_json;"), 8);
 
     // Invalid inserts.
     runInvalidStmt("INSERT INTO test_json(c1, c2) values (123, abc);");

java/yb-cql/src/test/java/org/yb/cql/TestJsonIndex.java

@@ -40,14 +40,26 @@ public void testIndex() throws Exception {
     session.execute("CREATE INDEX jidx ON test_json_index(j1->'a'->>'b')");
     session.execute("CREATE INDEX cidx ON test_json_index(a_column)");
 
-    for (int h = 0; h < 3000; h++) {
+    int h;
+    for (h = 0; h < 3000; h++) {
       String jvalue = String.format("{ \"a\" : { \"b\" : \"bvalue_%d\" }," +
                                     "  \"a_column\" : %d }", h, h );
       String stmt = String.format("INSERT INTO test_json_index(h, j1, j2) VALUES (%d, '%s', '%s');",
                                   h, jvalue, jvalue);
       session.execute(stmt);
     }
 
+    // Insert various value formats to the JSONB column to make sure that the JSONB expression
+    // index supports null values.
+    session.execute(String.format("INSERT INTO test_json_index(h) values (%d);", h++));
+    session.execute(String.format("INSERT INTO test_json_index(h, j1) values (%d, 'null');", h++));
+    session.execute(String.format("INSERT INTO test_json_index(h, j1) values (%d, '\"abc\"');",
+                                  h++));
+    session.execute(String.format("INSERT INTO test_json_index(h, j1) values (%d, '3');", h++));
+    session.execute(String.format("INSERT INTO test_json_index(h, j1) values (%d, 'true');", h++));
+    session.execute(String.format("INSERT INTO test_json_index(h, j1) values (%d, 'false');", h++));
+    session.execute(String.format("INSERT INTO test_json_index(h, j1) values (%d, '2.0');", h++));
+
     long runtimeMillis;
     String query;
 

src/yb/common/ql_expr.cc

@@ -43,9 +43,13 @@ CHECKED_STATUS QLExprExecutor::EvalExpr(const QLExpressionPB& ql_expr,
       QLExprResult temp;
       const QLJsonColumnOperationsPB& json_ops = ql_expr.json_column();
       RETURN_NOT_OK(table_row.ReadColumn(json_ops.column_id(), temp.Writer()));
-      common::Jsonb jsonb;
-      temp.MoveToJsonb(&jsonb);
-      RETURN_NOT_OK(jsonb.ApplyJsonbOperators(json_ops, &result_writer.NewValue()));
+      if (temp.IsNull()) {
+        result_writer.SetNull();
+      } else {
+        common::Jsonb jsonb;
+        temp.MoveToJsonb(&jsonb);
+        RETURN_NOT_OK(jsonb.ApplyJsonbOperators(json_ops, &result_writer.NewValue()));
+      }
       break;
     }
 
@@ -872,6 +876,14 @@ const QLValuePB& QLExprResult::Value() const {
   return value_.value();
 }
 
+bool QLExprResult::IsNull() const {
+  if (existing_value_) {
+    return yb::IsNull(*existing_value_);
+  }
+
+  return value_.IsNull();
+}
+
 void QLExprResult::MoveTo(QLValuePB* out) {
   if (existing_value_) {
     *out = *existing_value_;

src/yb/common/ql_expr.h

@@ -55,6 +55,8 @@ class QLExprResult {
 
   QLExprResultWriter Writer();
 
+  bool IsNull() const;
+
  private:
   friend class QLExprResultWriter;