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# C# Native API

## 1. Feature Overview

IoTDB provides a C# native client driver and corresponding connection pool, offering object-oriented interfaces that allow direct assembly of time-series objects for writing without SQL construction. It is recommended to use the connection pool for multi-threaded parallel database operations.

## 2. Usage Instructions

**Environment Requirements:**

* .NET SDK >= 5.0 or .NET Framework 4.x
* Thrift >= 0.14.1
* NLog >= 4.7.9

**Dependency Installation:**

It supports installation using tools such as NuGet Package Manager or .NET CLI. Taking .NET CLI as an example:

If using .NET 5.0 or a later version of the SDK, enter the following command to install the latest NuGet package:

```Plain
dotnet add package Apache.IoTDB
```

## 3. Read/Write Operations

### 3.1 TableSessionPool

#### 3.1.1 Functional Description

The `TableSessionPool` defines basic operations for interacting with IoTDB, supporting data insertion, query execution, and session closure. It also serves as a connection pool to efficiently reuse connections and properly release resources when unused. This interface defines how to acquire sessions from the pool and how to close the pool.

#### 3.1.2 Method List

Below are the methods defined in `TableSessionPool` with detailed descriptions:

| Method                                                         | Description                                                                    | Parameters                                                                                                | Return Type                |
| ---------------------------------------------------------------- | -------------------------------------------------------------------------------- |-----------------------------------------------------------------------------------------------------------| ---------------------------- |
| `Open(bool enableRpcCompression)`                          | Opens a session connection with custom `enableRpcCompression`              | `enableRpcCompression`: Whether to enable `RpcCompression` (requires server-side configuration alignment) | `Task`                 |
| `Open()`                                                   | Opens a session connection without enabling `RpcCompression`               | None                                                                                                      | `Task`                 |
| `InsertAsync(Tablet tablet)`                               | Inserts a `Tablet` object containing time-series data into the database    | `tablet`: The Tablet object to insert                                                                     | `Task<int>`            |
| `ExecuteNonQueryStatementAsync(string sql)`                | Executes a non-query SQL statement (e.g., DDL/DML commands)                    | `sql`: The SQL statement to execute                                                                       | `Task<int>`            |
| `ExecuteQueryStatementAsync(string sql)`                   | Executes a query SQL statement and returns a `SessionDataSet` with results | `sql`: The SQL query to execute                                                                           | `Task<SessionDataSet>` |
| `ExecuteQueryStatementAsync(string sql, long timeoutInMs)` | Executes a query SQL statement with a timeout (milliseconds)                   | `sql`: The SQL query to execute <br> `timeoutInMs`: Query timeout in milliseconds                         | `Task<SessionDataSet>` |
| `Close()`                                                  | Closes the session and releases held resources                                 | None                                                                                                      | `Task`                 |

#### 3.1.3 Interface Examples

```C#
public async Task Open(bool enableRpcCompression, CancellationToken cancellationToken = default)

  public async Task Open(CancellationToken cancellationToken = default)

  public async Task<int> InsertAsync(Tablet tablet)

  public async Task<int> ExecuteNonQueryStatementAsync(string sql)
  
  public async Task<SessionDataSet> ExecuteQueryStatementAsync(string sql)

  public async Task<SessionDataSet> ExecuteQueryStatementAsync(string sql, long timeoutInMs)
  
  public async Task Close()
```

### 3.2 TableSessionPool.Builder

#### 3.2.1 Functional Description

The `TableSessionPool.Builder` class configures and creates instances of `TableSessionPool`, allowing developers to set connection parameters, session settings, and pooling behaviors.

#### 3.2.2 Configuration Options

Below are the available configuration options for `TableSessionPool.Builder` and their defaults:

| ​**Configuration Method**            | ​**Description**                                                        | ​**Default Value**                                |
| --------------------------------------------- | -------------------------------------------------------------------------------- |---------------------------------------------------|
| `SetHost(string host)`                  | Sets the IoTDB node host                                                       | `localhost`                                       |
| `SetPort(int port)`                     | Sets the IoTDB node port                                                       | `6667`                                            |
| `SetNodeUrls(List nodeUrls)`            | Sets IoTDB cluster node URLs (overrides `SetHost`/`SetPort` when used) | Not set                                           |
| `SetUsername(string username)`          | Sets the connection username                                                   | `"root"`                                          |
| `SetPassword(string password)`          | Sets the connection password                                                   | `"TimechoDB@2021"` //before V2.0.6 it is root     |
| `SetFetchSize(int fetchSize)`           | Sets the fetch size for query results                                          | `1024`                                            |
| `SetZoneId(string zoneId)`              | Sets the timezone ZoneID                                                       | `UTC+08:00`                                       |
| `SetPoolSize(int poolSize)`             | Sets the maximum number of sessions in the connection pool                     | `8`                                               |
| `SetEnableRpcCompression(bool enable)`  | Enables/disables RPC compression                                               | `false`                                           |
| `SetConnectionTimeoutInMs(int timeout)` | Sets the connection timeout in milliseconds                                    | `500`                                             |
| `SetDatabase(string database)`          | Sets the target database name                                                  | `""`                                              |

#### 3.2.3 Interface Examples

```c#
public Builder SetHost(string host)
    {
      _host = host;
      return this;
    }

    public Builder SetPort(int port)
    {
      _port = port;
      return this;
    }

    public Builder SetUsername(string username)
    {
      _username = username;
      return this;
    }

    public Builder SetPassword(string password)
    {
      _password = password;
      return this;
    }

    public Builder SetFetchSize(int fetchSize)
    {
      _fetchSize = fetchSize;
      return this;
    }

    public Builder SetZoneId(string zoneId)
    {
      _zoneId = zoneId;
      return this;
    }

    public Builder SetPoolSize(int poolSize)
    {
      _poolSize = poolSize;
      return this;
    }

    public Builder SetEnableRpcCompression(bool enableRpcCompression)
    {
      _enableRpcCompression = enableRpcCompression;
      return this;
    }

    public Builder SetConnectionTimeoutInMs(int timeout)
    {
      _connectionTimeoutInMs = timeout;
      return this;
    }

    public Builder SetNodeUrls(List<string> nodeUrls)
    {
      _nodeUrls = nodeUrls;
      return this;
    }

    protected internal Builder SetSqlDialect(string sqlDialect)
    {
      _sqlDialect = sqlDialect;
      return this;
    }

    public Builder SetDatabase(string database)
    {
      _database = database;
      return this;
    }
    
    public Builder()
    {
      _host = "localhost";
      _port = 6667;
      _username = "root";
      _password = "TimechoDB@2021"; //before V2.0.6 it is root
      _fetchSize = 1024;
      _zoneId = "UTC+08:00";
      _poolSize = 8;
      _enableRpcCompression = false;
      _connectionTimeoutInMs = 500;
      _sqlDialect = IoTDBConstant.TABLE_SQL_DIALECT;
      _database = "";
    }

    public TableSessionPool Build()
    {
      SessionPool sessionPool;
      // if nodeUrls is not empty, use nodeUrls to create session pool
      if (_nodeUrls.Count > 0)
      {
        sessionPool = new SessionPool(_nodeUrls, _username, _password, _fetchSize, _zoneId, _poolSize, _enableRpcCompression, _connectionTimeoutInMs, _sqlDialect, _database);
      }
      else
      {
        sessionPool = new SessionPool(_host, _port, _username, _password, _fetchSize, _zoneId, _poolSize, _enableRpcCompression, _connectionTimeoutInMs, _sqlDialect, _database);
      }
      return new TableSessionPool(sessionPool);
    }
```

## 4. Example

Complete example : [samples/Apache.IoTDB.Samples/TableSessionPoolTest.cs](https://github.com/apache/iotdb-client-csharp/blob/main/samples/Apache.IoTDB.Samples/TableSessionPoolTest.cs)

```c#
/*
 * 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.
 */

using System;
using System.Collections.Generic;
using System.Threading.Tasks;
using Apache.IoTDB.DataStructure;

namespace Apache.IoTDB.Samples;

public class TableSessionPoolTest
{
  private readonly SessionPoolTest sessionPoolTest;

  public TableSessionPoolTest(SessionPoolTest sessionPoolTest)
  {
    this.sessionPoolTest = sessionPoolTest;
  }

  public async Task Test()
  {
    await TestCleanup();

    await TestSelectAndInsert();
    await TestUseDatabase();
    // await TestCleanup();
  }


  public async Task TestSelectAndInsert()
  {
    var tableSessionPool = new TableSessionPool.Builder()
            .SetNodeUrls(sessionPoolTest.nodeUrls)
            .SetUsername(sessionPoolTest.username)
            .SetPassword(sessionPoolTest.password)
            .SetFetchSize(1024)
            .Build();

    await tableSessionPool.Open(false);

    if (sessionPoolTest.debug) tableSessionPool.OpenDebugMode();


    await tableSessionPool.ExecuteNonQueryStatementAsync("CREATE DATABASE test1");
    await tableSessionPool.ExecuteNonQueryStatementAsync("CREATE DATABASE test2");

    await tableSessionPool.ExecuteNonQueryStatementAsync("use test2");

    // or use full qualified table name
    await tableSessionPool.ExecuteNonQueryStatementAsync(
        "create table test1.table1(region_id STRING TAG, plant_id STRING TAG, device_id STRING TAG, model STRING ATTRIBUTE, temperature FLOAT FIELD, humidity DOUBLE FIELD) with (TTL=3600000)");

    await tableSessionPool.ExecuteNonQueryStatementAsync(
        "create table table2(region_id STRING TAG, plant_id STRING TAG, color STRING ATTRIBUTE, temperature FLOAT FIELD, speed DOUBLE FIELD) with (TTL=6600000)");

    // show tables from current database
    var res = await tableSessionPool.ExecuteQueryStatementAsync("SHOW TABLES");
    res.ShowTableNames();
    while (res.HasNext()) Console.WriteLine(res.Next());
    await res.Close();

    // show tables by specifying another database
    // using SHOW tables FROM
    res = await tableSessionPool.ExecuteQueryStatementAsync("SHOW TABLES FROM test1");
    res.ShowTableNames();
    while (res.HasNext()) Console.WriteLine(res.Next());
    await res.Close();

    var tableName = "testTable1";
    List<string> columnNames =
        new List<string> {
            "region_id",
            "plant_id",
            "device_id",
            "model",
            "temperature",
            "humidity" };
    List<TSDataType> dataTypes =
        new List<TSDataType>{
            TSDataType.STRING,
            TSDataType.STRING,
            TSDataType.STRING,
            TSDataType.STRING,
            TSDataType.FLOAT,
            TSDataType.DOUBLE};
    List<ColumnCategory> columnCategories =
        new List<ColumnCategory>{
            ColumnCategory.TAG,
            ColumnCategory.TAG,
            ColumnCategory.TAG,
            ColumnCategory.ATTRIBUTE,
            ColumnCategory.FIELD,
            ColumnCategory.FIELD};
    var values = new List<List<object>> { };
    var timestamps = new List<long> { };
    for (long timestamp = 0; timestamp < 100; timestamp++)
    {
      timestamps.Add(timestamp);
      values.Add(new List<object> { "1", "5", "3", "A", 1.23F + timestamp, 111.1 + timestamp });
    }
    var tablet = new Tablet(tableName, columnNames, columnCategories, dataTypes, values, timestamps);

    await tableSessionPool.InsertAsync(tablet);


    res = await tableSessionPool.ExecuteQueryStatementAsync("select * from testTable1 "
          + "where region_id = '1' and plant_id in ('3', '5') and device_id = '3'");
    res.ShowTableNames();
    while (res.HasNext()) Console.WriteLine(res.Next());
    await res.Close();

    await tableSessionPool.Close();
  }


  public async Task TestUseDatabase()
  {
    var tableSessionPool = new TableSessionPool.Builder()
            .SetNodeUrls(sessionPoolTest.nodeUrls)
            .SetUsername(sessionPoolTest.username)
            .SetPassword(sessionPoolTest.password)
            .SetDatabase("test1")
            .SetFetchSize(1024)
            .Build();

    await tableSessionPool.Open(false);

    if (sessionPoolTest.debug) tableSessionPool.OpenDebugMode();


    // show tables from current database
    var res = await tableSessionPool.ExecuteQueryStatementAsync("SHOW TABLES");
    res.ShowTableNames();
    while (res.HasNext()) Console.WriteLine(res.Next());
    await res.Close();

    await tableSessionPool.ExecuteNonQueryStatementAsync("use test2");

    // show tables from current database
    res = await tableSessionPool.ExecuteQueryStatementAsync("SHOW TABLES");
    res.ShowTableNames();
    while (res.HasNext()) Console.WriteLine(res.Next());
    await res.Close();

    await tableSessionPool.Close();
  }

  public async Task TestCleanup()
  {
    var tableSessionPool = new TableSessionPool.Builder()
            .SetNodeUrls(sessionPoolTest.nodeUrls)
            .SetUsername(sessionPoolTest.username)
            .SetPassword(sessionPoolTest.password)
            .SetFetchSize(1024)
            .Build();

    await tableSessionPool.Open(false);

    if (sessionPoolTest.debug) tableSessionPool.OpenDebugMode();

    await tableSessionPool.ExecuteNonQueryStatementAsync("drop database test1");
    await tableSessionPool.ExecuteNonQueryStatementAsync("drop database test2");

    await tableSessionPool.Close();
  }
}
```