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From lars hofhansl <la...@apache.org>
Subject Re: Compactions nice to have features
Date Sat, 04 Oct 2014 17:31:16 GMT
Hi Vladimir,

these are very interesting.
A few comments:
- bulkload - you mean not by loading pre-created HFiles? If you do that there would be no
compaction during the import as the files are simply moved into place.
- local compaction IO limit. Limiting the number of compaction threads (1 by default) is not
good enough ... ? You can cause too much harm even with a single thread compacting per region
server?

- rack IO throttle. We should add that to accommodate for over subscription at the ToR level.
- cluster wide compaction storms. Yeah, that's bad. Can be alleviated by spreading timed major
compactions out. (in our clusters we set the interval to 1 week and the jitter to 1/2 week)
- what do you think about off-peak compaction? We have that in part as the compaction ratio
can be set differently for off peak hours


Generally I like the idea of being able to pace compaction better.
Do you want to file jiras for these? Doesn't mean you have to do all the work :)


-- Lars



________________________________
 From: Vladimir Rodionov <vladrodionov@gmail.com>
To: "dev@hbase.apache.org" <dev@hbase.apache.org> 
Sent: Friday, October 3, 2014 10:34 PM
Subject: Compactions nice to have features
 

I am thinking about the following:

1. Compaction On/Off per CF, Table, cluster. Both: minor and major

Good during bulk load.

- Disable compaction for table 'T'
- Load 1B rows
- Enable compaction for table 'T'

2. Local Compaction I/O throttle

Set I/O limit per RS

3. Rack Compaction I/O throttle

Set I/O limit per server rack. Good to control uplink bandwidth.

4. Cluster Compaction I/O throttle. Good to avoid compaction storms

-Vladimir Rodionov
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