在 Azure Cosmos DB 中管理衝突解決方案原則

發行項
08/15/2024

適用於：NoSQL

使用多重區域寫入時，如果有多個用戶端寫入至同一個項目，便可能會發生衝突。發生衝突時，您可使用不同的衝突解決原則來解決衝突。本文說明如何管理衝突解決原則。

提示

您只能在建立容器時指定衝突解決原則，而且無法在建立容器之後修改。

建立最後寫入為準衝突解決原則

這些範例示範如何設定最後寫入為準衝突解決原則的容器。最後寫入為準的預設路徑是時間戳記欄位或 _ts 屬性。針對適用於 NoSQL 的 API，這也可設定為數值類型的使用者定義路徑。發生衝突時，會以最大值為準。如果未設定路徑或路徑無效，便會預設為 _ts。已使用此原則解決的衝突將不會出現在衝突摘要中。此原則可供所有 API 使用。

DocumentCollection lwwCollection = await createClient.CreateDocumentCollectionIfNotExistsAsync(
  UriFactory.CreateDatabaseUri(this.databaseName), new DocumentCollection
  {
      Id = this.lwwCollectionName,
      ConflictResolutionPolicy = new ConflictResolutionPolicy
      {
          Mode = ConflictResolutionMode.LastWriterWins,
          ConflictResolutionPath = "/myCustomId",
      },
  });

Container container = await createClient.GetDatabase(this.databaseName)
    .CreateContainerIfNotExistsAsync(new ContainerProperties(this.lwwCollectionName, "/partitionKey")
    {
        ConflictResolutionPolicy = new ConflictResolutionPolicy()
        {
            Mode = ConflictResolutionMode.LastWriterWins,
            ResolutionPath = "/myCustomId",
        }
    });

Java V4 SDK

非同步
Sync

Java SDK V4 (Maven com.azure::azure-cosmos) 非同步 API


ConflictResolutionPolicy policy = ConflictResolutionPolicy.createLastWriterWinsPolicy("/myCustomId");

CosmosContainerProperties containerProperties = new CosmosContainerProperties(container_id, partition_key);
containerProperties.setConflictResolutionPolicy(policy);
/* ...other container config... */
database.createContainerIfNotExists(containerProperties).block();

JAVA SDK V4 (Maven com.azure::azure-cosmos) 同步 API


ConflictResolutionPolicy policy = ConflictResolutionPolicy.createLastWriterWinsPolicy("/myCustomId");

CosmosContainerProperties containerProperties = new CosmosContainerProperties(container_id, partition_key);
containerProperties.setConflictResolutionPolicy(policy);
/* ...other container config... */
database.createContainerIfNotExists(containerProperties);

Java V2 SDK

Async Java V2 SDK
Sync Java V2 SDK

Async Java V2 SDK (Maven com.microsoft.azure::azure-cosmosdb)

DocumentCollection collection = new DocumentCollection();
collection.setId(id);
ConflictResolutionPolicy policy = ConflictResolutionPolicy.createLastWriterWinsPolicy("/myCustomId");
collection.setConflictResolutionPolicy(policy);
DocumentCollection createdCollection = client.createCollection(databaseUri, collection, null).toBlocking().value();

(Maven com.microsoft.azure::azure-documentdb)

DocumentCollection lwwCollection = new DocumentCollection();
lwwCollection.setId(this.lwwCollectionName);
ConflictResolutionPolicy lwwPolicy = ConflictResolutionPolicy.createLastWriterWinsPolicy("/myCustomId");
lwwCollection.setConflictResolutionPolicy(lwwPolicy);
DocumentCollection createdCollection = this.tryCreateDocumentCollection(createClient, database, lwwCollection);

Node.js/JavaScript/TypeScript SDK

const database = client.database(this.databaseName);
const { container: lwwContainer } = await database.containers.createIfNotExists(
  {
    id: this.lwwContainerName,
    conflictResolutionPolicy: {
      mode: "LastWriterWins",
      conflictResolutionPath: "/myCustomId"
    }
  }
);

Python SDK

database = client.get_database_client(database=database_id)
lww_conflict_resolution_policy = {'mode': 'LastWriterWins', 'conflictResolutionPath': '/regionId'}
lww_container = database.create_container(id=lww_container_id, partition_key=PartitionKey(path="/id"), 
    conflict_resolution_policy=lww_conflict_resolution_policy)

使用預存程序建立自訂衝突解決原則

這些範例示範如何設定自訂衝突解決原則的容器。此原則會使用預存程序中的邏輯來解決衝突。如果指定了預存程序來解決衝突，除非指定的預存程序中發生錯誤，否則衝突不會顯示在衝突摘要中。

使用容器建立原則之後，您必須建立預存程序。以下 .NET SDK 範例顯示此工作流程的範例。只有適用於 NoSQL 的 API 才支援此原則。

自訂衝突解決預存程序範例

您必須使用如下所示的函式簽章來實作自訂衝突解決預存程序。函式名稱不需要符合向容器註冊預存程序時所使用的名稱，但符合的話可簡化命名程序。下面會說明必須為此預存程序實作的參數。

incomingItem：在產生衝突的認可中，所要插入或更新的項目。若為刪除作業，此參數為 null。
existingItem目前認可的項目。在更新中，此值為非 Null，若為插入或刪除作業，則為 Null。
isTombstone：布林值，會指出 incomingItem 是否與先前刪除的項目衝突。若為 true，則 existingItem 也是 null。
conflictingItems：容器中所有項目的認可版本所構成的陣列，這些項目與 incomingItem 的識別碼或任何其他唯一的索引屬性有所衝突。

重要

和任何預存程序一樣，自訂衝突解決程序可以存取任何具有相同分割索引鍵的資料，並可執行任何插入、更新或刪除作業來解決衝突。

這個預存程序範例會藉由從 /myCustomId 路徑選取最低值來解決衝突。

function resolver(incomingItem, existingItem, isTombstone, conflictingItems) {
  var collection = getContext().getCollection();

  if (!incomingItem) {
      if (existingItem) {

          collection.deleteDocument(existingItem._self, {}, function (err, responseOptions) {
              if (err) throw err;
          });
      }
  } else if (isTombstone) {
      // delete always wins.
  } else {
      if (existingItem) {
          if (incomingItem.myCustomId > existingItem.myCustomId) {
              return; // existing item wins
          }
      }

      var i;
      for (i = 0; i < conflictingItems.length; i++) {
          if (incomingItem.myCustomId > conflictingItems[i].myCustomId) {
              return; // existing conflict item wins
          }
      }

      // incoming item wins - clear conflicts and replace existing with incoming.
      tryDelete(conflictingItems, incomingItem, existingItem);
  }

  function tryDelete(documents, incoming, existing) {
      if (documents.length > 0) {
          collection.deleteDocument(documents[0]._self, {}, function (err, responseOptions) {
              if (err) throw err;

              documents.shift();
              tryDelete(documents, incoming, existing);
          });
      } else if (existing) {
          collection.replaceDocument(existing._self, incoming,
              function (err, documentCreated) {
                  if (err) throw err;
              });
      } else {
          collection.createDocument(collection.getSelfLink(), incoming,
              function (err, documentCreated) {
                  if (err) throw err;
              });
      }
  }
}

.NET SDK

.NET SDK V2
.NET SDK V3

DocumentCollection udpCollection = await createClient.CreateDocumentCollectionIfNotExistsAsync(
  UriFactory.CreateDatabaseUri(this.databaseName), new DocumentCollection
  {
      Id = this.udpCollectionName,
      ConflictResolutionPolicy = new ConflictResolutionPolicy
      {
          Mode = ConflictResolutionMode.Custom,
          ConflictResolutionProcedure = string.Format("dbs/{0}/colls/{1}/sprocs/{2}", this.databaseName, this.udpCollectionName, "resolver"),
      },
  });

//Create the stored procedure
await clients[0].CreateStoredProcedureAsync(
UriFactory.CreateStoredProcedureUri(this.databaseName, this.udpCollectionName, "resolver"), new StoredProcedure
{
    Id = "resolver",
    Body = File.ReadAllText(@"resolver.js")
});

Container container = await createClient.GetDatabase(this.databaseName)
    .CreateContainerIfNotExistsAsync(new ContainerProperties(this.udpCollectionName, "/partitionKey")
    {
        ConflictResolutionPolicy = new ConflictResolutionPolicy()
        {
            Mode = ConflictResolutionMode.Custom,
            ResolutionProcedure = string.Format("dbs/{0}/colls/{1}/sprocs/{2}", this.databaseName, this.udpCollectionName, "resolver")
        }
    });

await container.Scripts.CreateStoredProcedureAsync(
    new StoredProcedureProperties("resolver", File.ReadAllText(@"resolver.js"))
);

Java V4 SDK

非同步
Sync

Java SDK V4 (Maven com.azure::azure-cosmos) 非同步 API


ConflictResolutionPolicy policy = ConflictResolutionPolicy.createCustomPolicy("resolver");

CosmosContainerProperties containerProperties = new CosmosContainerProperties(container_id, partition_key);
containerProperties.setConflictResolutionPolicy(policy);
/* ...other container config... */
database.createContainerIfNotExists(containerProperties).block();

JAVA SDK V4 (Maven com.azure::azure-cosmos) 同步 API


ConflictResolutionPolicy policy = ConflictResolutionPolicy.createCustomPolicy("resolver");

CosmosContainerProperties containerProperties = new CosmosContainerProperties(container_id, partition_key);
containerProperties.setConflictResolutionPolicy(policy);
/* ...other container config... */
database.createContainerIfNotExists(containerProperties);

Java V2 SDK

Async Java V2 SDK
Sync Java V2 SDK

Async Java V2 SDK (Maven com.microsoft.azure::azure-cosmosdb)

DocumentCollection collection = new DocumentCollection();
collection.setId(id);
ConflictResolutionPolicy policy = ConflictResolutionPolicy.createCustomPolicy("resolver");
collection.setConflictResolutionPolicy(policy);
DocumentCollection createdCollection = client.createCollection(databaseUri, collection, null).toBlocking().value();

(Maven com.microsoft.azure::azure-documentdb)

DocumentCollection udpCollection = new DocumentCollection();
udpCollection.setId(this.udpCollectionName);
ConflictResolutionPolicy udpPolicy = ConflictResolutionPolicy.createCustomPolicy(
        String.format("dbs/%s/colls/%s/sprocs/%s", this.databaseName, this.udpCollectionName, "resolver"));
udpCollection.setConflictResolutionPolicy(udpPolicy);
DocumentCollection createdCollection = this.tryCreateDocumentCollection(createClient, database, udpCollection);

建立容器之後，您必須建立 resolver 預存程序。

Node.js/JavaScript/TypeScript SDK

const database = client.database(this.databaseName);
const { container: udpContainer } = await database.containers.createIfNotExists(
  {
    id: this.udpContainerName,
    conflictResolutionPolicy: {
      mode: "Custom",
      conflictResolutionProcedure: `dbs/${this.databaseName}/colls/${
        this.udpContainerName
      }/sprocs/resolver`
    }
  }
);

建立容器之後，您必須建立 resolver 預存程序。

Python SDK

database = client.get_database_client(database=database_id)
udp_custom_resolution_policy = {'mode': 'Custom' }
udp_container = database.create_container(id=udp_container_id, partition_key=PartitionKey(path="/id"),
    conflict_resolution_policy=udp_custom_resolution_policy)

建立容器之後，您必須建立 resolver 預存程序。

建立自訂衝突解決原則

這些範例示範如何設定自訂衝突解決原則的容器。透過此實作，每個衝突都會顯示在衝突摘要中。您必須個別處理衝突摘要中的衝突。

.NET SDK

.NET SDK V2
.NET SDK V3

DocumentCollection manualCollection = await createClient.CreateDocumentCollectionIfNotExistsAsync(
  UriFactory.CreateDatabaseUri(this.databaseName), new DocumentCollection
  {
      Id = this.manualCollectionName,
      ConflictResolutionPolicy = new ConflictResolutionPolicy
      {
          Mode = ConflictResolutionMode.Custom,
      },
  });

Container container = await createClient.GetDatabase(this.databaseName)
    .CreateContainerIfNotExistsAsync(new ContainerProperties(this.manualCollectionName, "/partitionKey")
    {
        ConflictResolutionPolicy = new ConflictResolutionPolicy()
        {
            Mode = ConflictResolutionMode.Custom
        }
    });

Java V4 SDK

非同步
Sync

Java SDK V4 (Maven com.azure::azure-cosmos) 非同步 API


ConflictResolutionPolicy policy = ConflictResolutionPolicy.createCustomPolicy();

CosmosContainerProperties containerProperties = new CosmosContainerProperties(container_id, partition_key);
containerProperties.setConflictResolutionPolicy(policy);
/* ...other container config... */
database.createContainerIfNotExists(containerProperties).block();

JAVA SDK V4 (Maven com.azure::azure-cosmos) 同步 API


ConflictResolutionPolicy policy = ConflictResolutionPolicy.createCustomPolicy();

CosmosContainerProperties containerProperties = new CosmosContainerProperties(container_id, partition_key);
containerProperties.setConflictResolutionPolicy(policy);
/* ...other container config... */
database.createContainerIfNotExists(containerProperties);

Java V2 SDK

Async Java V2 SDK
Sync Java V2 SDK

Async Java V2 SDK (Maven com.microsoft.azure::azure-cosmosdb)

DocumentCollection collection = new DocumentCollection();
collection.setId(id);
ConflictResolutionPolicy policy = ConflictResolutionPolicy.createCustomPolicy();
collection.setConflictResolutionPolicy(policy);
DocumentCollection createdCollection = client.createCollection(databaseUri, collection, null).toBlocking().value();

(Maven com.microsoft.azure::azure-documentdb)

DocumentCollection manualCollection = new DocumentCollection();
manualCollection.setId(this.manualCollectionName);
ConflictResolutionPolicy customPolicy = ConflictResolutionPolicy.createCustomPolicy(null);
manualCollection.setConflictResolutionPolicy(customPolicy);
DocumentCollection createdCollection = client.createCollection(database.getSelfLink(), collection, null).getResource();

Node.js/JavaScript/TypeScript SDK

const database = client.database(this.databaseName);
const {
  container: manualContainer
} = await database.containers.createIfNotExists({
  id: this.manualContainerName,
  conflictResolutionPolicy: {
    mode: "Custom"
  }
});

Python SDK

database = client.get_database_client(database=database_id)
manual_resolution_policy = {'mode': 'Custom'}
manual_container = database.create_container(id=manual_container_id, partition_key=PartitionKey(path="/id"), 
    conflict_resolution_policy=manual_resolution_policy)

從衝突摘要讀取

這些範例示範如何從容器的衝突摘要讀取。衝突只會基於幾個原因顯示在衝突摘要中：

衝突未自動解決
衝突導致指定的預存程序發生錯誤
衝突解決原則已設定為 [自訂]，而且未指定預存程序來處理衝突

.NET SDK

.NET SDK V2
.NET SDK V3

FeedResponse<Conflict> conflicts = await delClient.ReadConflictFeedAsync(this.collectionUri);

FeedIterator<ConflictProperties> conflictFeed = container.Conflicts.GetConflictQueryIterator();
while (conflictFeed.HasMoreResults)
{
    FeedResponse<ConflictProperties> conflicts = await conflictFeed.ReadNextAsync();
    foreach (ConflictProperties conflict in conflicts)
    {
        // Read the conflicted content
        MyClass intendedChanges = container.Conflicts.ReadConflictContent<MyClass>(conflict);
        MyClass currentState = await container.Conflicts.ReadCurrentAsync<MyClass>(conflict, new PartitionKey(intendedChanges.MyPartitionKey));

        // Do manual merge among documents
        await container.ReplaceItemAsync<MyClass>(intendedChanges, intendedChanges.Id, new PartitionKey(intendedChanges.MyPartitionKey));

        // Delete the conflict
        await container.Conflicts.DeleteAsync(conflict, new PartitionKey(intendedChanges.MyPartitionKey));
    }
}

Java SDK

Java V4 SDK (Maven com.azure::azure-cosmos)

int requestPageSize = 3;
CosmosQueryRequestOptions options = new CosmosQueryRequestOptions();

CosmosPagedFlux<CosmosConflictProperties> conflictReadFeedFlux = container.readAllConflicts(options);

conflictReadFeedFlux.byPage(requestPageSize).toIterable().forEach(page -> {

    int expectedNumberOfConflicts = 0;
    int numberOfResults = 0;
    Iterator<CosmosConflictProperties> pageIt = page.getElements().iterator();

    while (pageIt.hasNext()) {
        CosmosConflictProperties conflictProperties = pageIt.next();

        // Read the conflict and committed item
        CosmosAsyncConflict conflict = container.getConflict(conflictProperties.getId());
        CosmosConflictResponse response = conflict.read(new CosmosConflictRequestOptions()).block();

        // response.
    }
});

Async Java V2 SDK (Maven com.microsoft.azure::azure-cosmosdb)

FeedResponse<Conflict> response = client.readConflicts(this.manualCollectionUri, null)
                    .first().toBlocking().single();
for (Conflict conflict : response.getResults()) {
    /* Do something with conflict */
}

(Maven com.microsoft.azure::azure-documentdb)

Iterator<Conflict> conflictsIterator = client.readConflicts(this.collectionLink, null).getQueryIterator();
while (conflictsIterator.hasNext()) {
    Conflict conflict = conflictsIterator.next();
    /* Do something with conflict */
}

Node.js/JavaScript/TypeScript SDK

const container = client
  .database(this.databaseName)
  .container(this.lwwContainerName);

const { result: conflicts } = await container.conflicts.readAll().toArray();

Python

conflicts_iterator = iter(container.list_conflicts())
conflict = next(conflicts_iterator, None)
while conflict:
    # Do something with conflict
    conflict = next(conflicts_iterator, None)

下一步

深入了解下列 Azure Cosmos DB 概念：

共用方式為

在 Azure Cosmos DB 中管理衝突解決方案原則

建立最後寫入為準衝突解決原則

.NET SDK

Java V4 SDK

Java V2 SDK

Node.js/JavaScript/TypeScript SDK

Python SDK

使用預存程序建立自訂衝突解決原則

自訂衝突解決預存程序範例

.NET SDK

Java V4 SDK

Java V2 SDK

Node.js/JavaScript/TypeScript SDK

Python SDK

建立自訂衝突解決原則

.NET SDK

Java V4 SDK

Java V2 SDK

Node.js/JavaScript/TypeScript SDK

Python SDK

從衝突摘要讀取

.NET SDK

Java SDK

Node.js/JavaScript/TypeScript SDK

Python

下一步

意見反應

其他資源