在 c# 中 CosmosDB DocumentDB 和 SqlAPI 性能低下

Question

我需要运行查询 returns 来自 CosmosDB 集合的大约 30,000 项。要在代码 I post 中执行此查询，执行时间大约为 2 分半钟，即使将吞吐量提高 40 倍，您也没有得到实质性的改进，时间减少到 1 分钟。

public static async Task<IEnumerable<T>> GetItemsCompact(string whereclause)
{
    string collectionToUse;
    SqlQuerySpec sqlQuerySpec = new SqlQuerySpec();

    if (typeof(T).ToString().IndexOf("Telemetry") != -1)
    {
        DocumentDBRepository<CosmosDBTelemetry>.Initialize();
        collectionToUse = AppSettings.Collection;
        sqlQuerySpec.QueryText = "SELECT c.messageUID as messageUID, ";
        sqlQuerySpec.QueryText += "c.deviceId as deviceId, ";
        sqlQuerySpec.QueryText += "udf.UDF_VIn(c.VIn) as VIn, ";
        sqlQuerySpec.QueryText += "udf.UDF_AIn(c.AIn) as AIn, ";
        sqlQuerySpec.QueryText += "udf.UDF_W(c.W) as W, ";
        sqlQuerySpec.QueryText += "udf.UDF_Var(c.Var) as Var, ";
        sqlQuerySpec.QueryText += "c.EventProcessedUtcTime as EventProcessedUtcTime ";
        sqlQuerySpec.QueryText += "from Telemetry c ";
        sqlQuerySpec.QueryText += whereclause;
    }
    else
    {
        DocumentDBRepository<CosmosDBEvents>.Initialize();
        collectionToUse = AppSettings.Collection2;
        sqlQuerySpec.QueryText = "select doc.uid as uid, ";
        sqlQuerySpec.QueryText += "doc.deviceId as deviceId, ";
        sqlQuerySpec.QueryText += "doc.eventId as eventId, ";
        sqlQuerySpec.QueryText += "doc.ts as ts, ";
        sqlQuerySpec.QueryText += "doc.startTS as startTS, ";
        sqlQuerySpec.QueryText += "doc.endTS as endTS, ";
        sqlQuerySpec.QueryText += "doc.no as no, ";
        sqlQuerySpec.QueryText += "doc.params as params, ";
        sqlQuerySpec.QueryText += "doc.tags as tags ";
        sqlQuerySpec.QueryText += "from Events doc ";
        sqlQuerySpec.QueryText += whereclause;
    }

    FeedOptions opt = new FeedOptions
    {
        EnableCrossPartitionQuery = true,
        MaxItemCount = -1
    };

    IDocumentQuery<T> query = client.CreateDocumentQuery<T>(

    UriFactory.CreateDocumentCollectionUri(AppSettings.Database, collectionToUse), sqlQuerySpec,opt).AsDocumentQuery();

    List<T> results = new List<T>();

    while (query.HasMoreResults)
    {
        results.AddRange(await query.ExecuteNextAsync<T>());
    }

   return results;
  }

有人可以帮助我提高性能吗？

Answer 1

这完全在意料之中。 Cosmos DB 不应该那样使用。您正在执行跨分区查询。理想情况下，这永远不应该发生，至少不会在您的应用程序的正常逻辑中发生。最重要的是，您将 MaxItemCount 设置为 -1。这意味着您希望 Cosmos return 单个页面中的所有内容。不建议这样做，因为 Cosmos DB 仅 return 分页结果，而这是最好的时候。您可以将页面大小更改为 100-250 之类的值，但这仍然不会显着提高性能。 Cosmos DB 不适合在这种情况下执行。

在 c# 中 CosmosDB DocumentDB 和 SqlAPI 性能低下

Slow performance with CosmosDB DocumentDB and SqlAPI in c#

c#

azure-cosmosdb

azure-cosmosdb-sqlapi