Comment by tav | Hacker News Reader

Comment by tav | Hacker News Reader

For any AWS folk on here, it'd be great to know how this fits with the consistency guarantees. Can we do strongly consistent index queries?

Also, any chance we could have strongly consistent auto-expiring keys in DynamoDB? Would make DynamoDB a very useful tool for synchronisation/lease management and other funky uses.

I also sent Werner an email asking if it would be suitable to use DynamoDB as a block device — you could then build a filesystem on top and benefit from DynamoDB features like replication, consistency, etc. Unfortunately, I fear the email must have slipped through his no-doubt-busy-inbox. If any of DynamoDB developers could shed any light on its suitability as a block device, that would be awesome! Thanks.

> I also sent Werner an email asking if it would be suitable to use DynamoDB as a block device — you could then build a filesystem on top and benefit from DynamoDB features like replication, consistency, etc.

This. 100 times. A filesystem was my first thought when DDB was announced last year. I can't imagine it would be harder to build than GridFS was. [1]

That said, I'm not talking about a FUSE-like filesystem. More like HDFS or GridFS -- a blobstore+ if you will.

[1] http://docs.mongodb.org/manual/core/gridfs/

DynamoDB is optimized for storing relatively small records on redundant fast SSDs. You would blow through all your read and write units instantly using it as a BLOB store.

Well, that depends on your BLOBs, how you use them and what it's worth to you, doesn't it?

My name is Jon, and I’m a member of the DynamoDB team. To your specific question about consistency guarantees, local secondary indexes support both strong and eventual consistency. The indexes are updated automatically when the primary index is updated.

For more information, have a look at our FAQ guide and Developer Guides.

http://aws.amazon.com/dynamodb/faqs/

http://aws.amazon.com/documentation/dynamodb/

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