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From "Aleksey Yeschenko (JIRA)" <>
Subject [jira] [Comment Edited] (CASSANDRA-6134) More efficient BatchlogManager
Date Wed, 02 Oct 2013 15:54:43 GMT


Aleksey Yeschenko edited comment on CASSANDRA-6134 at 10/2/13 3:53 PM:

Haven't looked at it carefully yet, but, you can't change the batchlog cf like this and break
backward compatibility entirely.

was (Author: iamaleksey):
Haven't looked at it carefully yet, but, you can't change the batchlog cf like this and breaking
backward compatibility entirely.

> More efficient BatchlogManager
> ------------------------------
>                 Key: CASSANDRA-6134
>                 URL:
>             Project: Cassandra
>          Issue Type: Improvement
>            Reporter: Oleg Anastasyev
>            Priority: Minor
>         Attachments: BatchlogManager.txt
> As we discussed earlier in CASSANDRA-6079 this is the new BatchManager.
> It stores batch records in 
> {code}
> CREATE TABLE batchlog (
>   id_partition int,
>   id timeuuid,
>   data blob,
>   PRIMARY KEY (id_partition, id)
> {code}
> where id_partition is minute-since-epoch of id uuid. 
> So when it scans for batches to replay ot scans within a single partition for  a slice
of ids since last processed date till now minus write timeout.
> So no full batchlog CF scan and lot of randrom reads are made on normal cycle. 
> Other improvements:
> 1. It runs every 1/2 of write timeout and replays all batches written within 0.9 * write
timeout from now. This way we ensure, that batched updates will be replayed to th moment client
times out from coordinator.
> 2. It submits all mutations from single batch in parallel (Like StorageProxy do). Old
implementation played them one-by-one, so client can see half applied batches in CF for a
long time (depending on size of batch).
> 3. It fixes a subtle racing bug with incorrect hint ttl calculation

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