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From Aaron Morton <>
Subject Re: Question about 'duplicate' columns
Date Tue, 06 Aug 2013 08:10:31 GMT
Yes. If you overwrite much older data with new data both "versions" of the column will remain
on disk until compaction get's to work on both fragments of the row.

Aaron Morton
Cassandra Consultant
New Zealand


On 6/08/2013, at 6:48 PM, Franc Carter <> wrote:

> I've been thinking through some cases that I can see happening at some point and thought
I'd ask on the list to see if my understanding is correct.
> Say a bunch of columns have been loaded 'a long time ago', i.e long enough in the past
that they have been compacted. My understanding is that if some these columns get reloaded
then they are likely to sit in additional sstables until the larger sstable is called up for
compaction, which might be a while.
> The case that springs to mind is filling small gaps in data by doing bulk loads around
the gap to make sure that the gap is filled.
> Have I understood correctly ?
> thanks
> -- 
> Franc Carter | Systems architect | Sirca Ltd
> |
> Tel: +61 2 8355 2514 
> Level 4, 55 Harrington St, The Rocks NSW 2000
> PO Box H58, Australia Square, Sydney NSW 1215

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