Question

我有一个DynamoDB，我用它来存储有关EC2实例的一些信息，所以我使用实例id作为HashKey。

每周一次，我运行的代码会在此表中插入大量记录：

AmazonDynamoDB amazonDynamoDB = new AmazonDynamoDBClient();
DynamoDBMapper mapper = new DynamoDBMapper(amazonDynamoDB);

// saving records
List<FailedBatch> failedBatch = mapper.batchSave(recordsToSave);

我只关心最新信息，所以如果我试图插入的HashKey已经存在于数据库中，我想覆盖DynamoDB中的旧记录。但是，每次我尝试插入这样的值时，操作都会失败（failedBatch），因为它无法处理重复。

有没有办法如何使用DynamoDB实现此行为，还是必须更改表设计？

Answer 1

Batch operations cannot update items. See:

http://docs.aws.amazon.com/amazondynamodb/latest/APIReference/API_BatchWriteItem.html

BatchWriteItem cannot update items. To update items, use the UpdateItem API.

What I would do is:

attempt to do the batch write
look at failures that come back
batch get the failed items and batch write them to a temp table
batch write delete all the items that were failed (already existing)
batch write the failures again to main table
purge all items from temp table

As an alternative you can use the UpdateItem api but that's probably going to be slower.

DynamoDB - 使用批处理操作覆盖HashKey

1 个答案: