src/UserGuide/V0.13.x/API/Programming-Go-Native-API.md

<!--

    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.

-->

## Go Native API

### Dependencies

 * golang >= 1.13
 * make   >= 3.0
 * curl   >= 7.1.1
 * thrift 0.15.0
 * Linux、Macos or other unix-like systems
 * Windows+bash (WSL、cygwin、Git Bash)




### Installation

 * go mod

```sh
export GO111MODULE=on
export GOPROXY=https://goproxy.io

mkdir session_example && cd session_example

curl -o session_example.go -L https://github.com/apache/iotdb-client-go/raw/main/example/session_example.go

go mod init session_example
go run session_example.go
```

* GOPATH

```sh
# get thrift 0.13.0
go get github.com/apache/thrift
cd $GOPATH/src/github.com/apache/thrift
git checkout 0.13.0

mkdir -p $GOPATH/src/iotdb-client-go-example/session_example
cd $GOPATH/src/iotdb-client-go-example/session_example
curl -o session_example.go -L https://github.com/apache/iotdb-client-go/raw/main/example/session_example.go
go run session_example.go
```

### How to Use the SessionPool
SessionPool is a wrapper of a Session Set. Using SessionPool, the user do not need to consider how to reuse a session connection.
If there is no available connections and the pool reaches its max size, the all methods will hang until there is a available connection.
The PutBack method must be called after use

#### New sessionPool

```go
config := &client.PoolConfig{
    Host:     host,
    Port:     port,
    UserName: user,
    Password: password,
}
sessionPool = client.NewSessionPool(config, 3, 60000, 60000, false)
```

#### Get session through sessionPool, putback after use

set storage group

```go
session, err := sessionPool.GetSession()
defer sessionPool.PutBack(session)
if err == nil {
    session.SetStorageGroup(sg)
}
```

query statement

```go
var timeout int64 = 1000
session, err := sessionPool.GetSession()
defer sessionPool.PutBack(session)
if err != nil {
    log.Print(err)
    return
}
sessionDataSet, err := session.ExecuteQueryStatement(sql, &timeout)
if err == nil {
    defer sessionDataSet.Close()
    printDataSet1(sessionDataSet)
} else {
    log.Println(err)
}
```