使用 DynamoDB 專用 PartiQL 執行交易 - Amazon DynamoDB

本文為英文版的機器翻譯版本,如內容有任何歧義或不一致之處,概以英文版為準。

使用 DynamoDB 專用 PartiQL 執行交易

本節說明如何搭配 DynamoDB 專用 PartiQL 使用交易。PartiQL 交易限制為全部 100 個陳述式 (動作)。

如需 DynamoDB 交易的詳細資訊,請參閱管理包含 DynamoDB 交易的複雜工作流程

注意

整個交易必須由讀取陳述式或寫入陳述式所組成。你不能在一個交易中混合兩者。EXISTS 函數為例外。可用類似於 TransactWriteItems API 操作中的 ConditionCheck 方式檢查項目特定屬性的條件。

語法

[ { "Statement":" statement ", "Parameters":[ { " parametertype " : " parametervalue " }, ...] } , ... ]

參數

陳述式

(必要) DynamoDB 專用 PartiQL 支援的陳述式。

注意

整個交易必須由讀取陳述式或寫入陳述式所組成。你不能在一個交易中混合兩者。

parametertype

(選用) DynamoDB 類型,如果在指定 PartiQL 陳述式時使用了參數。

parametervalue

(選用) 參數值,如果在指定 PartiQL 陳述式時使用了參數。

傳回值

此陳述式不會傳回寫入作業 (插入、更新或刪除) 的任何值。但是,它根據 WHERE 子句中指定的條件回傳讀取操作 (SELECT) 的不同值。

注意

如果任何單一 INSERT、UPDATE 或 DELETE 操作傳回錯誤,交易會取消並出現 TransactionCanceledException 例外狀況,且取消原因程式碼會包含個別單一操作的錯誤。

範例

以下範例會以交易形式執行多個陳述式。

AWS CLI
  1. 將以下 JSON 程式碼儲存至名為 partiql.json 的檔案

    [ { "Statement": "EXISTS(SELECT * FROM \"Music\" where Artist='No One You Know' and SongTitle='Call Me Today' and Awards is MISSING)" }, { "Statement": "INSERT INTO Music value {'Artist':?,'SongTitle':'?'}", "Parameters": [{\"S\": \"Acme Band\"}, {\"S\": \"Best Song\"}] }, { "Statement": "UPDATE \"Music\" SET AwardsWon=1 SET AwardDetail={'Grammys':[2020, 2018]} where Artist='Acme Band' and SongTitle='PartiQL Rocks'" } ]
  2. 在命令提示中執行下列命令。

    aws dynamodb execute-transaction --transact-statements file://partiql.json
Java
public class DynamoDBPartiqlTransaction { public static void main(String[] args) { // Create the DynamoDB Client with the region you want AmazonDynamoDB dynamoDB = createDynamoDbClient("us-west-2"); try { // Create ExecuteTransactionRequest ExecuteTransactionRequest executeTransactionRequest = createExecuteTransactionRequest(); ExecuteTransactionResult executeTransactionResult = dynamoDB.executeTransaction(executeTransactionRequest); System.out.println("ExecuteTransaction successful."); // Handle executeTransactionResult } catch (Exception e) { handleExecuteTransactionErrors(e); } } private static AmazonDynamoDB createDynamoDbClient(String region) { return AmazonDynamoDBClientBuilder.standard().withRegion(region).build(); } private static ExecuteTransactionRequest createExecuteTransactionRequest() { ExecuteTransactionRequest request = new ExecuteTransactionRequest(); // Create statements List<ParameterizedStatement> statements = getPartiQLTransactionStatements(); request.setTransactStatements(statements); return request; } private static List<ParameterizedStatement> getPartiQLTransactionStatements() { List<ParameterizedStatement> statements = new ArrayList<ParameterizedStatement>(); statements.add(new ParameterizedStatement() .withStatement("EXISTS(SELECT * FROM "Music" where Artist='No One You Know' and SongTitle='Call Me Today' and Awards is MISSING)")); statements.add(new ParameterizedStatement() .withStatement("INSERT INTO "Music" value {'Artist':'?','SongTitle':'?'}") .withParameters(new AttributeValue("Acme Band"),new AttributeValue("Best Song"))); statements.add(new ParameterizedStatement() .withStatement("UPDATE "Music" SET AwardsWon=1 SET AwardDetail={'Grammys':[2020, 2018]} where Artist='Acme Band' and SongTitle='PartiQL Rocks'")); return statements; } // Handles errors during ExecuteTransaction execution. Use recommendations in error messages below to add error handling specific to // your application use-case. private static void handleExecuteTransactionErrors(Exception exception) { try { throw exception; } catch (TransactionCanceledException tce) { System.out.println("Transaction Cancelled, implies a client issue, fix before retrying. Error: " + tce.getErrorMessage()); } catch (TransactionInProgressException tipe) { System.out.println("The transaction with the given request token is already in progress, consider changing " + "retry strategy for this type of error. Error: " + tipe.getErrorMessage()); } catch (IdempotentParameterMismatchException ipme) { System.out.println("Request rejected because it was retried with a different payload but with a request token that was already used, " + "change request token for this payload to be accepted. Error: " + ipme.getErrorMessage()); } catch (Exception e) { handleCommonErrors(e); } } private static void handleCommonErrors(Exception exception) { try { throw exception; } catch (InternalServerErrorException isee) { System.out.println("Internal Server Error, generally safe to retry with exponential back-off. Error: " + isee.getErrorMessage()); } catch (RequestLimitExceededException rlee) { System.out.println("Throughput exceeds the current throughput limit for your account, increase account level throughput before " + "retrying. Error: " + rlee.getErrorMessage()); } catch (ProvisionedThroughputExceededException ptee) { System.out.println("Request rate is too high. If you're using a custom retry strategy make sure to retry with exponential back-off. " + "Otherwise consider reducing frequency of requests or increasing provisioned capacity for your table or secondary index. Error: " + ptee.getErrorMessage()); } catch (ResourceNotFoundException rnfe) { System.out.println("One of the tables was not found, verify table exists before retrying. Error: " + rnfe.getErrorMessage()); } catch (AmazonServiceException ase) { System.out.println("An AmazonServiceException occurred, indicates that the request was correctly transmitted to the DynamoDB " + "service, but for some reason, the service was not able to process it, and returned an error response instead. Investigate and " + "configure retry strategy. Error type: " + ase.getErrorType() + ". Error message: " + ase.getErrorMessage()); } catch (AmazonClientException ace) { System.out.println("An AmazonClientException occurred, indicates that the client was unable to get a response from DynamoDB " + "service, or the client was unable to parse the response from the service. Investigate and configure retry strategy. "+ "Error: " + ace.getMessage()); } catch (Exception e) { System.out.println("An exception occurred, investigate and configure retry strategy. Error: " + e.getMessage()); } } }

下列範例顯示當 DynamoDB 讀取 WHERE 子句中指定之不同條件的項目時,不同的傳回值。

AWS CLI
  1. 將以下 JSON 程式碼儲存至名為 partiql.json 的檔案

    [ // Item exists and projected attribute exists { "Statement": "SELECT * FROM "Music" WHERE Artist='No One You Know' and SongTitle='Call Me Today'" }, // Item exists but projected attributes do not exist { "Statement": "SELECT non_existent_projected_attribute FROM "Music" WHERE Artist='No One You Know' and SongTitle='Call Me Today'" }, // Item does not exist { "Statement": "SELECT * FROM "Music" WHERE Artist='No One I Know' and SongTitle='Call You Today'" } ]
  2. 在命令提示中執行命令。

    aws dynamodb execute-transaction --transact-statements file://partiql.json
  3. 會傳回下列回應:

    { "Responses": [ // Item exists and projected attribute exists { "Item": { "Artist":{ "S": "No One You Know" }, "SongTitle":{ "S": "Call Me Today" } } }, // Item exists but projected attributes do not exist { "Item": {} }, // Item does not exist {} ] }