fix response with no result (#1679)

Author: chernser

client-v2/src/main/java/com/clickhouse/client/api/Client.java

@@ -788,9 +788,11 @@ public List<GenericRecord> queryAll(String sqlQuery) {
         try {
             try (QueryResponse response = query(sqlQuery).get(TIMEOUT, TimeUnit.MILLISECONDS)) {
                 List<GenericRecord> records = new ArrayList<>();
-                ClickHouseBinaryFormatReader reader = new RowBinaryWithNamesAndTypesFormatReader(response.getInputStream());
-                while (reader.hasNext()) {
-                    records.add(new MapBackedRecord(reader.next(), reader.getSchema()));
+                if (response.getResultRows() > 0) {
+                    ClickHouseBinaryFormatReader reader = new RowBinaryWithNamesAndTypesFormatReader(response.getInputStream());
+                    while (reader.hasNext()) {
+                        records.add(new MapBackedRecord(reader.next(), reader.getSchema()));
+                    }
                 }
                 return records;
             }

client-v2/src/main/java/com/clickhouse/client/api/data_formats/RowBinaryWithNamesAndTypesFormatReader.java

@@ -23,11 +23,14 @@ public RowBinaryWithNamesAndTypesFormatReader(InputStream inputStream) {
 
     public RowBinaryWithNamesAndTypesFormatReader(InputStream inputStream, QuerySettings querySettings) {
         super(inputStream, querySettings, null);
-        setSchema(readSchema());
+        readSchema();
     }
 
-    private TableSchema readSchema() {
+    private void readSchema() {
         try {
+            if (inputStream.available() < 1) {
+                return;
+            }
             TableSchema headerSchema = new TableSchema();
             List<String> columns = new ArrayList<>();
             int nCol = chInputStream.readVarInt();
@@ -39,7 +42,7 @@ private TableSchema readSchema() {
                 headerSchema.addColumn(columns.get(i), chInputStream.readUnicodeString());
             }
 
-            return headerSchema;
+            setSchema(headerSchema);
         } catch (IOException e) {
             throw new ClientException("Failed to read header", e);
         }

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

@@ -135,13 +135,27 @@ public void testReadRecordsGetFirstRecord() throws Exception {
         Assert.assertFalse(iter.hasNext());
     }
 
+    @Test(groups = {"integration"})
+    public void testReadRecordsNoResult() throws Exception {
+        Records records = client.queryRecords("CREATE DATABASE IF NOT EXISTS test_db").get(3, TimeUnit.SECONDS);
+
+        Iterator<GenericRecord> iter = records.iterator();
+        Assert.assertFalse(iter.hasNext());
+    }
+
     @Test(groups = {"integration"})
     public void testQueryAll() throws Exception {
         prepareDataSet(DATASET_TABLE, DATASET_COLUMNS, DATASET_VALUE_GENERATORS, 10);
         GenericRecord hostnameRecord = client.queryAll("SELECT hostname()").stream().findFirst().get();
         Assert.assertNotNull(hostnameRecord);
     }
 
+    @Test(groups = {"integration"})
+    public void testQueryAllNoResult() throws Exception {
+        List<GenericRecord>  records = client.queryAll("CREATE DATABASE IF NOT EXISTS test_db");
+        Assert.assertTrue(records.isEmpty());
+    }
+
     @Test(groups = {"integration"}, enabled = false)
     public void testQueryJSONWith64BitIntegers() throws ExecutionException, InterruptedException {
         // won't work because format settings are set thru separate statement.