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From "Peter Bailis (JIRA)" <j...@apache.org>
Subject [jira] [Commented] (CASSANDRA-7056) Add RAMP transactions
Date Mon, 30 Jun 2014 20:36:26 GMT

    [ https://issues.apache.org/jira/browse/CASSANDRA-7056?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=14048119#comment-14048119
] 

Peter Bailis commented on CASSANDRA-7056:
-----------------------------------------

bq.  I doubt this will be dramatically more complex, but the approach to implementation is
fundamentally different. It seems to me supporting transactions of arbitrary size is an equally
powerful win to consistent transactions.

I agree "streaming" batches could be really useful. In effect, you're turning an operation
you'd have to perform client-side (e.g., you can simulate "streaming" by simply buffering
your write sets and then calling one big BATCH) into a server-assisted one (where your proposed
read-buffer/memtable stores the pending inserts while you're still deciding what goes into
the transaction). From the RAMP perspective, this doesn't change things substantially -- you
just have to make sure to propagate the appropriate txn metadata after you've determined what
writes made it into the batch.

[~benedict]: towards your point on non-QUORUM but QUORUM reads, I agree there are some cool
tricks to play. There's some additional complexity in these optimizations, but, the basic
observation is a good one: if I already have a transaction ID I want to read from and the
metadata associated with it, all I have to do is find the matching versions which don't necessarily
require QUORUM reads for "consistency" w.r.t. the ID.

> Add RAMP transactions
> ---------------------
>
>                 Key: CASSANDRA-7056
>                 URL: https://issues.apache.org/jira/browse/CASSANDRA-7056
>             Project: Cassandra
>          Issue Type: Wish
>          Components: Core
>            Reporter: Tupshin Harper
>            Priority: Minor
>
> We should take a look at [RAMP|http://www.bailis.org/blog/scalable-atomic-visibility-with-ramp-transactions/]
transactions, and figure out if they can be used to provide more efficient LWT (or LWT-like)
operations.



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