added total_rows_to_read to metrics

Author: chernser

client-v2/src/main/java/com/clickhouse/client/api/query/QueryResponse.java

@@ -133,6 +133,15 @@ public long getResultRows() {
         return operationMetrics.getMetric(ServerMetrics.RESULT_ROWS).getLong();
     }
 
+
+    /**
+     * Alias for {@link ServerMetrics#TOTAL_ROWS_TO_READ}
+     * @return estimated number of rows to read
+     */
+    public long getTotalRowsToRead() {
+        return operationMetrics.getMetric(ServerMetrics.TOTAL_ROWS_TO_READ).getLong();
+    }
+
     /**
      * Alias for {@link OperationMetrics#getQueryId()}
      * @return query id of the request

client-v2/src/test/java/com/clickhouse/client/query/QueryTests.java

@@ -2018,4 +2018,12 @@ public void testLowCardinalityValues() throws Exception {
             Assert.assertEquals(record.getString("keyword"), values[rowId]);
         }
     }
+
+    @Test(groups = {"integration"})
+    public void testGettingRowsBeforeLimit() throws Exception {
+        try (QueryResponse response = client.query("SELECT number FROM system.numbers LIMIT 100").get()) {
+            Assert.assertTrue(response.getResultRows() < 1000);
+            Assert.assertEquals(response.getTotalRowsToRead(), 100);
+        }
+    }
 }