使用 C# 存取 InfluxDB

最近專案可能會用到 InfluxDB，之前嘗試過的經驗主要是用在監控上，不是直接使用 C# 存取，所以趁著專案開始前先試試看可以如何存取，免得延誤專案時程

基本環境說明

macOS Mojave 10.14.6
.NET Core SDK 2.2.301 (.NET Core Runtime 2.2.6)
Docker for Mac 2.1.0.2 (37877)
InfluxDB v1.7.8
NuGet package
- InfluxData.Net 8.0.1

建立 InfluxDB instance

8086 是 HTTP API port
~~8083 是管理介面的 port~~
~~透過環境變數 (INFLUXDB_ADMIN_ENABLED) 來啟用管理介面~~
管理介面已在 InfluxDB 1.3.0 移除
INFLUXDB_ADMIN_USER 未指定時將不會建立管理者
INFLUXDB_ADMIN_PASSWORD 設定管理者密碼，未指定時會直接在 standard out 顯示
INFLUXDB_HTTP_AUTH_ENABLED 啟用認證

~~bash docker run -d -p 8086:8086 -p 8083:8083 -e INFLUXDB_ADMIN_ENABLED=true influxdb~~

docker run -d -p 8086:8086 -e INFLUXDB_ADMIN_USER=admin -e INFLUXDB_ADMIN_PASSWORD=pass.123 -e INFLUXDB_HTTP_AUTH_ENABLED=true influxdb

使用方式

建立 influxdb client

var influxDbClient = new InfluxDbClient("http://localhost:8086/", "admin", "pass.123", InfluxDbVersion.Latest);

建立 Database

var dbName = "testDb";
var response = await influxDbClient.Database.CreateDatabaseAsync("testDb");

Insert 資料

var pointToWrite = new Point()
{
    Name = "yowkoTest", // serie/measurement/table to write into
    Tags = new Dictionary<string, object>()
    {
        { "SensorId", 8 },
        { "SerialNumber", "00AF123B" }
    },
    Fields = new Dictionary<string, object>()
    {
        { "SensorState", "active" },
        { "Humidity", 431 },
        { "Temperature", 22.1 },
        { "Resistance", 34957 }
    },
    Timestamp = DateTime.UtcNow // optional (can be set to any DateTime moment)
};

var response = await influxDbClient.Client.WriteAsync(pointToWrite, dbName);

Select 資料

var query = "SELECT * FROM yowkoTest WHERE SensorState = 'active' ";
var response = await influxDbClient.Client.QueryAsync(query, dbName);

Update 資料

influxDB 沒有專屬的 update 語法，可以透過 insert 相同 Timestamp 來覆蓋資料，不過僅限於 field 內容，如是 tag 會多一個資料

var now = DateTime.UtcNow;
            
var pointToWrite = new Point()
{
    Name = "yowkoTest", // serie/measurement/table to write into
    Tags = new Dictionary<string, object>()
    {
        { "tag1", "yowkoTag1" }
    },
    Fields = new Dictionary<string, object>()
    {
        {"purpose","forUpdate"}
    },
    Timestamp =now // optional (can be set to any DateTime moment)
};
    
var response = await influxDbClient.Client.WriteAsync(pointToWrite, dbName);

var pointToWrite2 = new Point()
{
    Name = "yowkoTest", // serie/measurement/table to write into
    Tags = new Dictionary<string, object>()
    {
        { "tag1", "yowkoTag1" }
    },
    Fields = new Dictionary<string, object>()
    {
        {"purpose","updated"}
    },
    Timestamp =now // optional (can be set to any DateTime moment)
};
var response2 = await influxDbClient.Client.WriteAsync(pointToWrite2, dbName);

Delete 資料

var query = "DROP SERIES FROM yowkoTest WHERE SensorId = '8' ";
var response = await influxDbClient.Client.QueryAsync(query, dbName);

心得

InfluxDB 比較偏重 insert 與 select，對於 update 與 delete 支援度不好，我想應該是設計理論與用途的關係，不過對於相關的用法、名詞、特性還是不太熟悉，過陣子較上手些後再來筆記囉

文章目錄

使用 C# 存取 InfluxDB

基本環境說明

建立 InfluxDB instance

使用方式

心得

參考資訊