Review on Spanner (OSDI'12)

1) Is the problem real?
The need of schemes that want strong consistency in wide-area replications is the main problem. It is real.

2) What is the solution’s main idea (nugget)?
The nugget in Spanner is it assigns globally-meaningful commit timestamps to transactions, thus can support for strong consistency in wide-area replications.

More precisely, the key component is a new TrueTime API and its implementation.

3) Why is solution different from previous work?

Megastore and DynamoDB also provide consistent replication across datacenters. DynamoDB can only replicates within a region, whereas Spanner can replicates globally. Megastore has writes conflicts and high communication cost, whereas Spanner do not have these shortcomings.

4) Does the paper (or do you) identify any fundamental/hard trade-offs? 

Although Spanner is scalable in the number of nodes, the node-local data structures have relatively poor performance on complex SQL queries, because they were designed for simple key-value accesses.  

5) Do you think the paper will be influential in 10 years? Why or why not?
Yes, Since bigtable is a great success, I think spanner is the next generation of Google database.