Question

我正在AWS上使用DynamoDB数据库。我有一个已启用其流的表。据我了解，流应该捕获有关此表的任何活动。

但是，有时表的活动（通常是对某些记录的修改）不会记录在流中。我知道新信息已写入表这一事实，因为我可以在表指标中看到此活动。

为什么会这样？这并不罕见，它每天发生几次。有什么办法可以刷新类似的内容吗？我知道流中的分片中的数据会自行更新和刷新，但是还有什么办法吗？

我使用这种方法浏览流的分片：

    private void processShards(AmazonDynamoDBStreamsClient sC, DescribeStreamResult dsr, String arn) {
                String lastEvaluatedShardId = null;

                final List<Shard> shards = dsr.getStreamDescription().getShards();
                do {
                    // Process each shard on this page
                    for (Shard shard : shards) {
                        final String shardId = shard.getShardId();

                        if (!shardMap.containsKey(shardId)) {
                            shardMap.put(shardId, new String[2]);
                            shardMap.get(shardId)[0] = "";
                            shardMap.get(shardId)[1] = "open";
                            System.out.println("Shards map contains " + shardMap.size() + " shards.");
                        }

                        if (shardMap.get(shardId)[1].matches("open")) {
                            GetShardIteratorRequest getShardIteratorRequest = null;
                            if (shardMap.get(shardId)[0].matches("")) {
                                getShardIteratorRequest = new GetShardIteratorRequest()
                                        .withStreamArn(arn)
                                        .withShardId(shardId)
                                        .withShardIteratorType(ShardIteratorType.TRIM_HORIZON);
                            } else {
                                getShardIteratorRequest = new GetShardIteratorRequest()
                                        .withStreamArn(arn)
                                        .withShardId(shardId)
                                        .withShardIteratorType(ShardIteratorType.AFTER_SEQUENCE_NUMBER)
                                        .withSequenceNumber(shardMap.get(shardId)[0]);
                            }
                            final GetShardIteratorResult sir = sC.getShardIterator(getShardIteratorRequest);
                            String currentShardIter = sir.getShardIterator();

                            while (currentShardIter != null) {
                                final GetRecordsResult getRecordsResult = sC.getRecords(new GetRecordsRequest()
                                        .withShardIterator(currentShardIter));
                                final List<Record> records = getRecordsResult.getRecords();
                                if (!records.isEmpty()) {
                                    for (Record record : records) {
                                        final StreamRecord sr = record.getDynamodb();
 // process record ..... do something
                                        shardMap.get(shardId)[0] = sr.getSequenceNumber();
                                    }
                                    currentShardIter = getRecordsResult.getNextShardIterator();
                                } else {
                                    break;
                                }
                            }

                            final String endSeq = shard.getSequenceNumberRange().getEndingSequenceNumber();
                            if (endSeq != null) { 
                                shardMap.get(shardId)[1] = "closed";
                            }
                        } else {
                            // do nothing shard is closed
                        }
                    }

                    lastEvaluatedShardId = dsr.getStreamDescription().getLastEvaluatedShardId();

                } while (lastEvaluatedShardId != null);
            }

shardMap是-> HashMap <String, String[]> shardMap = new HashMap <String, String[]>();

在处理所有分片时，我可以看到那里有时不存在新信息。

可能是什么问题？谢谢您的帮助。

AWS DynamoDB流不会使用新信息进行更新

0 个答案: