DynamoDB慢速扫描查询

Question

When I do this query in AWS console it returns immediately:

But from the Java code, it never completes:

    final List<TransactionDetails> tx = dynamoDBMapper //
            .scan(TransactionDetails.class, new DynamoDBScanExpression() //
                    .withConsistentRead(false)
                    .withLimit(maxRecords) //
                    .withFilterConditionEntry("time", new Condition().withComparisonOperator(ComparisonOperator.LT)
                            .withAttributeValueList(new AttributeValue(Long.toString(time)))));

    return tx;  

Answer 1

The DynamoDB console only shows 100 results at a time. The DynamoDB mapper implements the scan operation such that it will automatically iterate over all the items in your table. It will make as many requests to Dynamo as it takes to scan the whole table, and it will also retry if it gets throttled.

For small tables, a scan usually completes in a few seconds, but a larger table, especially if you don't have enough provisioned read capacity, could take minutes, hours, or days..

So - check the size of your table and the provisioned capacity. The scan will complete but how long it takes definitely depends on these two variables.