[fix](Tvf) return empty set when tvf queries an empty file or an erro…

…r uri (apache#25280)

### Before:
return errors when tvf queries an empty file or an error uri:
1. get parsed schema failed, empty csv file
2. Can not get first file, please check uri.

### Now:
we just return empty set when tvf queries an empty file or an error uri.
```sql
mysql> select * from s3( 
"uri" = "https://error_uri/exp_1.csv", 
"s3.access_key"= "xx", 
"s3.secret_key" = "yy", 
"format" = "csv") limit 10;

Empty set (1.29 sec)
```

docs/en/docs/lakehouse/file.md

@@ -193,3 +193,9 @@ FROM s3(
  "use_path_style" = "true");
 ```
 
+
+### Note
+
+1. If the URI specified by the `S3 / HDFS` TVF is not matched with the file, or all the matched files are empty files, then the` S3 / HDFS` TVF will return to the empty result set. In this case, using the `DESC FUNCTION` to view the schema of this file, you will get a dummy column` __dummy_col`, which can be ignored.
+
+2. If the format of the TVF is specified to `CSV`, and the read file is not a empty file but the first line of this file is empty, then it will prompt the error `The first line is empty, can not parse column numbers`. This is because the schema cannot be parsed from the first line of the file

docs/en/docs/sql-manual/sql-functions/table-functions/hdfs.md

@@ -51,7 +51,7 @@ hdfs(
 
 Related parameters for accessing hdfs:
 
-- `uri`: (required) hdfs uri.
+- `uri`: (required) hdfs uri. If the uri path does not exist or the files are empty files, hdfs tvf will return an empty result set.
 - `fs.defaultFS`: (required)
 - `hadoop.username`: (required) Can be any string, but cannot be empty.
 - `hadoop.security.authentication`: (optional)

docs/en/docs/sql-manual/sql-functions/table-functions/s3.md

@@ -63,6 +63,7 @@ Related parameters for accessing S3:
 > Note: URI currently supports three SCHEMA: http://, https:// and s3://.
 > 1. If you use http:// or https://, you will decide whether to use the 'path style' to access s3 based on the 'use_path_style' parameter
 > 2. If you use s3://, you will use the "virtual-hosted style' to access the s3, 'use_path_style' parameter is invalid.
+> 3. If the uri path does not exist or the files are empty files, s3 tvf will return an empty result set.
 >
 > For detailed use cases, you can refer to Best Practice at the bottom.
 

docs/zh-CN/docs/lakehouse/file.md

@@ -193,3 +193,9 @@ FROM s3(
  "use_path_style" = "true");
 ``` 
 
+### 注意事项
+
+1. 如果 `S3 / hdfs` tvf指定的uri匹配不到文件，或者匹配到的所有文件都是空文件，那么 `S3 / hdfs` tvf将会返回空结果集。在这种情况下使用`DESC FUNCTION`查看这个文件的Schema，会得到一列虚假的列`__dummy_col`，可忽略这一列。
+
+2. 如果指定tvf的format为csv，所读文件不为空文件但文件第一行为空，则会提示错误`The first line is empty, can not parse column numbers`, 这因为无法通过该文件的第一行解析出schema。
+

docs/zh-CN/docs/sql-manual/sql-functions/table-functions/hdfs.md

@@ -53,7 +53,7 @@ hdfs(
 **参数说明**
 
 访问hdfs相关参数：
-- `uri`：（必填） 访问hdfs的uri。
+- `uri`：（必填） 访问hdfs的uri。如果uri路径不存在或文件都是空文件，hdfs tvf将返回空集合。
 - `fs.defaultFS`：（必填）
 - `hadoop.username`： （必填）可以是任意字符串，但不能为空
 - `hadoop.security.authentication`：（选填）

docs/zh-CN/docs/sql-manual/sql-functions/table-functions/s3.md

@@ -66,6 +66,7 @@ S3 tvf中的每一个参数都是一个 `"key"="value"` 对。
 > 注意：uri目前支持三种schema：http://, https:// 和 s3://
 > 1. 如果使用http://或https://, 则会根据 'use_path_style' 参数来决定是否使用'path style'方式访问s3
 > 2. 如果使用s3://, 则都使用 'virtual-hosted style' 方式访问s3, 'use_path_style'参数无效。
+> 3. 如果uri路径不存在或文件都是空文件，s3 tvf将返回空集合
 >
 > 详细使用案例可以参考最下方 Best Practice。
 

fe/fe-core/src/main/java/org/apache/doris/tablefunction/ExternalFileTableValuedFunction.java

@@ -344,22 +344,27 @@ public List<Column> getTableColumns() throws AnalysisException {
  TNetworkAddress address = new TNetworkAddress(be.getHost(), be.getBrpcPort());
  try {
  PFetchTableSchemaRequest request = getFetchTableStructureRequest();
- Future<InternalService.PFetchTableSchemaResult> future = BackendServiceProxy.getInstance()
- .fetchTableStructureAsync(address, request);
-
- InternalService.PFetchTableSchemaResult result = future.get();
- TStatusCode code = TStatusCode.findByValue(result.getStatus().getStatusCode());
- String errMsg;
- if (code != TStatusCode.OK) {
- if (!result.getStatus().getErrorMsgsList().isEmpty()) {
- errMsg = result.getStatus().getErrorMsgsList().get(0);
- } else {
- errMsg = "fetchTableStructureAsync failed. backend address: "
- + address.getHostname() + ":" + address.getPort();
+ InternalService.PFetchTableSchemaResult result = null;
+
+ // `request == null` means we don't need to get schemas from BE,
+ // and we fill a dummy col for this table.
+ if (request != null) {
+ Future<InternalService.PFetchTableSchemaResult> future = BackendServiceProxy.getInstance()
+ .fetchTableStructureAsync(address, request);
+
+ result = future.get();
+ TStatusCode code = TStatusCode.findByValue(result.getStatus().getStatusCode());
+ String errMsg;
+ if (code != TStatusCode.OK) {
+ if (!result.getStatus().getErrorMsgsList().isEmpty()) {
+ errMsg = result.getStatus().getErrorMsgsList().get(0);
+ } else {
+ errMsg = "fetchTableStructureAsync failed. backend address: "
+ + address.getHostname() + ":" + address.getPort();
+ }
+ throw new AnalysisException(errMsg);
  }
- throw new AnalysisException(errMsg);
  }
-
  fillColumns(result);
  } catch (RpcException e) {
  throw new AnalysisException("fetchTableStructureResult rpc exception", e);
@@ -431,10 +436,12 @@ private Pair<Type, Integer> getColumnType(List<PTypeNode> typeNodes, int start)
  return Pair.of(type, parsedNodes);
  }
 
- private void fillColumns(InternalService.PFetchTableSchemaResult result)
- throws AnalysisException {
- if (result.getColumnNums() == 0) {
- throw new AnalysisException("The amount of column is 0");
+ private void fillColumns(InternalService.PFetchTableSchemaResult result) {
+ // `result == null` means we don't need to get schemas from BE,
+ // and we fill a dummy col for this table.
+ if (result == null) {
+ columns.add(new Column("__dummy_col", ScalarType.createStringType(), true));
+ return;
  }
  // add fetched file columns
  for (int idx = 0; idx < result.getColumnNums(); ++idx) {
@@ -450,7 +457,7 @@ private void fillColumns(InternalService.PFetchTableSchemaResult result)
  }
  }
 
- private PFetchTableSchemaRequest getFetchTableStructureRequest() throws AnalysisException, TException {
+ private PFetchTableSchemaRequest getFetchTableStructureRequest() throws TException {
  // set TFileScanRangeParams
  TFileScanRangeParams fileScanRangeParams = new TFileScanRangeParams();
  fileScanRangeParams.setFormatType(fileFormatType);
@@ -475,14 +482,19 @@ private PFetchTableSchemaRequest getFetchTableStructureRequest() throws Analysis
  // get first file, used to parse table schema
  TBrokerFileStatus firstFile = null;
  for (TBrokerFileStatus fileStatus : fileStatuses) {
- if (fileStatus.isIsDir()) {
+ if (fileStatus.isIsDir() || fileStatus.size == 0) {
  continue;
  }
  firstFile = fileStatus;
  break;
  }
+
+ // `firstFile == null` means:
+ // 1. No matching file path exists
+ // 2. All matched files have a size of 0
+ // For these two situations, we don't need to get schema from BE
  if (firstFile == null) {
- throw new AnalysisException("Can not get first file, please check uri.");
+ return null;
  }
 
  // set TFileRangeDesc

regression-test/data/external_table_p0/tvf/test_hdfs_tvf_error_uri.out

@@ -0,0 +1,6 @@
+-- This file is automatically generated. You should know what you did if you want to edit this
+-- !select1 --
+
+-- !desc1 --
+__dummy_col TEXT Yes false \N NONE
+

regression-test/data/load_p0/tvf/test_tvf_empty_file.out

@@ -0,0 +1,17 @@
+-- This file is automatically generated. You should know what you did if you want to edit this
+-- !select --
+
+-- !desc --
+__dummy_col TEXT Yes false \N NONE
+
+-- !select2 --
+1 doris 18
+2 nereids 20
+3 xxx 22
+4 yyy 21
+
+-- !des2 --
+c1 TEXT Yes false \N NONE
+c2 TEXT Yes false \N NONE
+c3 TEXT Yes false \N NONE
+

regression-test/data/load_p0/tvf/test_tvf_error_url.out

@@ -0,0 +1,11 @@
+-- This file is automatically generated. You should know what you did if you want to edit this
+-- !select --
+
+-- !desc --
+__dummy_col TEXT Yes false \N NONE
+
+-- !select2 --
+
+-- !desc2 --
+__dummy_col TEXT Yes false \N NONE
+

regression-test/suites/external_table_p0/tvf/test_hdfs_tvf_error_uri.groovy

@@ -0,0 +1,43 @@
+// Licensed to the Apache Software Foundation (ASF) under one
+// or more contributor license agreements. See the NOTICE file
+// distributed with this work for additional information
+// regarding copyright ownership. The ASF licenses this file
+// to you under the Apache License, Version 2.0 (the
+// "License"); you may not use this file except in compliance
+// with the License. You may obtain a copy of the License at
+//
+// http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing,
+// software distributed under the License is distributed on an
+// "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
+// KIND, either express or implied. See the License for the
+// specific language governing permissions and limitations
+// under the License.
+
+suite("test_hdfs_tvf_error_uri","external,hive,tvf,external_docker") {
+ String hdfs_port = context.config.otherConfigs.get("hdfs_port")
+ String externalEnvIp = context.config.otherConfigs.get("externalEnvIp")
+
+ // It's okay to use random `hdfsUser`, but can not be empty.
+ def hdfsUserName = "doris"
+ def format = "csv"
+ def defaultFS = "hdfs://${externalEnvIp}:${hdfs_port}"
+ def uri = ""
+
+ String enabled = context.config.otherConfigs.get("enableHiveTest")
+ if (enabled != null && enabled.equalsIgnoreCase("true")) {
+ // test csv format
+ uri = "${defaultFS}" + "/user/doris/preinstalled_data/csv_format_test/no_exist_file.csv"
+ format = "csv"
+ order_qt_select1 """ select * from HDFS(
+ "uri" = "${uri}",
+ "hadoop.username" = "${hdfsUserName}",
+ "format" = "${format}"); """
+
+ order_qt_desc1 """ desc function HDFS(
+ "uri" = "${uri}",
+ "hadoop.username" = "${hdfsUserName}",
+ "format" = "${format}"); """
+ }
+}

regression-test/suites/load_p0/tvf/test_tvf_empty_file.groovy

@@ -0,0 +1,69 @@
+// Licensed to the Apache Software Foundation (ASF) under one
+// or more contributor license agreements. See the NOTICE file
+// distributed with this work for additional information
+// regarding copyright ownership. The ASF licenses this file
+// to you under the Apache License, Version 2.0 (the
+// "License"); you may not use this file except in compliance
+// with the License. You may obtain a copy of the License at
+//
+// http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing,
+// software distributed under the License is distributed on an
+// "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
+// KIND, either express or implied. See the License for the
+// specific language governing permissions and limitations
+// under the License.
+
+suite("test_tvf_empty_file", "p0") {
+ String ak = getS3AK()
+ String sk = getS3SK()
+ String s3_endpoint = getS3Endpoint()
+ String region = getS3Region()
+ String bucket = context.config.otherConfigs.get("s3BucketName");
+
+ String path = "regression/datalake"
+
+ // ${path}/empty_file_test.csv is an empty file
+ // so it should return empty sets.
+ order_qt_select """ SELECT * FROM S3 (
+ "uri" = "http://${bucket}.${s3_endpoint}/${path}/empty_file_test.csv",
+ "ACCESS_KEY"= "${ak}",
+ "SECRET_KEY" = "${sk}",
+ "format" = "csv",
+ "region" = "${region}"
+ );
+ """
+
+ order_qt_desc """ desc function S3 (
+ "uri" = "http://${bucket}.${s3_endpoint}/${path}/empty_file_test.csv",
+ "ACCESS_KEY"= "${ak}",
+ "SECRET_KEY" = "${sk}",
+ "format" = "csv",
+ "region" = "${region}"
+ );
+ """
+
+ // ${path}/empty_file_test*.csv matches 3 files:
+ // empty_file_test.csv, empty_file_test_1.csv, empty_file_test_2.csv
+ // empty_file_test.csv is an empty file, but
+ // empty_file_test_1.csv and empty_file_test_2.csv have data
+ // so it should return data of empty_file_test_1.csv and empty_file_test_2.cs
+ order_qt_select2 """ SELECT * FROM S3 (
+ "uri" = "http://${bucket}.${s3_endpoint}/${path}/empty_file_test*.csv",
+ "ACCESS_KEY"= "${ak}",
+ "SECRET_KEY" = "${sk}",
+ "format" = "csv",
+ "region" = "${region}"
+ ) order by c1;
+ """
+
+ order_qt_des2 """ desc function S3 (
+ "uri" = "http://${bucket}.${s3_endpoint}/${path}/empty_file_test*.csv",
+ "ACCESS_KEY"= "${ak}",
+ "SECRET_KEY" = "${sk}",
+ "format" = "csv",
+ "region" = "${region}"
+ );
+ """
+}

regression-test/suites/load_p0/tvf/test_tvf_error_url.groovy

@@ -0,0 +1,61 @@
+// Licensed to the Apache Software Foundation (ASF) under one
+// or more contributor license agreements. See the NOTICE file
+// distributed with this work for additional information
+// regarding copyright ownership. The ASF licenses this file
+// to you under the Apache License, Version 2.0 (the
+// "License"); you may not use this file except in compliance
+// with the License. You may obtain a copy of the License at
+//
+// http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing,
+// software distributed under the License is distributed on an
+// "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
+// KIND, either express or implied. See the License for the
+// specific language governing permissions and limitations
+// under the License.
+
+suite("test_tvf_error_url", "p0") {
+ String ak = getS3AK()
+ String sk = getS3SK()
+ String s3_endpoint = getS3Endpoint()
+ String region = getS3Region()
+ String bucket = context.config.otherConfigs.get("s3BucketName");
+
+ String path = "select_tvf/no_exists_file_test"
+ order_qt_select """ SELECT * FROM S3 (
+ "uri" = "http://${s3_endpoint}/${bucket}/${path}/no_exist_file1.csv",
+ "ACCESS_KEY"= "${ak}",
+ "SECRET_KEY" = "${sk}",
+ "format" = "csv",
+ "region" = "${region}"
+ );
+ """
+
+ order_qt_desc """ desc function S3 (
+ "uri" = "http://${s3_endpoint}/${bucket}/${path}/no_exist_file1.csv",
+ "ACCESS_KEY"= "${ak}",
+ "SECRET_KEY" = "${sk}",
+ "format" = "csv",
+ "region" = "${region}"
+ );
+ """
+
+ order_qt_select2 """ SELECT * FROM S3 (
+ "uri" = "http://${s3_endpoint}/${bucket}/${path}/*.csv",
+ "ACCESS_KEY"= "${ak}",
+ "SECRET_KEY" = "${sk}",
+ "format" = "csv",
+ "region" = "${region}"
+ );
+ """
+
+ order_qt_desc2 """ desc function S3 (
+ "uri" = "http://${s3_endpoint}/${bucket}/${path}/*.csv",
+ "ACCESS_KEY"= "${ak}",
+ "SECRET_KEY" = "${sk}",
+ "format" = "csv",
+ "region" = "${region}"
+ );
+ """
+}