问题
I am thinking of building a chat app with AWS DynamoDB. The app will support 1:1 and group chats.
I want to create one table for each one of the chats, where there is a record for each sent chat text line. Is DynamoDB suitable for this kind of job?
I am also thinking of merging both tables. But is this a good idea, if there are – let's assume – 100k or 1000k users?
回答1:
I think you may run into problems with the read capacity on your table. The write capacity should be ok, as there are not so many messages coming in per second (e.g. 10 or so), but you'll need to constantly read from it for all users, so that'll be expensive.
If you want to use DynamoDB just as storage and distribute the chat messages like in any normal chat over the network, then it may make sense, depending on your use cases. You could, assuming you have a hash key UserId and Timestamp, query all messages from a specific user during a specific period as a result. If you want, however, search within the chat text (a much more useful feature, probably), then DynamoDB won't work per se. It's not like SQL, where you could do a LIKE '%abc%' query (which isn't a good idea in SQL either).
Probably you're better off using S3 as data storage and ElasticSearch as search instrument. If you require the aforementioned use case "get all messages from user X in timespan S" (as a simple example) you could additionally use DynamoDB to store metadata, such as UserId, Timestamp, PositionInFile or something like that.
来源：https://stackoverflow.com/questions/35213738/storing-chat-log-on-aws-dynamodb