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Posted to user@cassandra.apache.org by Franc Carter <fr...@sirca.org.au> on 2013/08/06 08:48:15 UTC
Question about 'duplicate' columns
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
<ma...@sirca.org.au>
franc.carter@sirca.org.au | www.sirca.org.au
Tel: +61 2 8355 2514
Level 4, 55 Harrington St, The Rocks NSW 2000
PO Box H58, Australia Square, Sydney NSW 1215
Re: Question about 'duplicate' columns
Posted by Franc Carter <fr...@sirca.org.au>.
On Tue, Aug 6, 2013 at 6:10 PM, Aaron Morton <aa...@thelastpickle.com>wrote:
> 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.
>
thanks
>
> Cheers
>
> -----------------
> Aaron Morton
> Cassandra Consultant
> New Zealand
>
> @aaronmorton
> http://www.thelastpickle.com
>
> On 6/08/2013, at 6:48 PM, Franc Carter <fr...@sirca.org.au> 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
> <ma...@sirca.org.au>
> franc.carter@sirca.org.au | www.sirca.org.au
> Tel: +61 2 8355 2514
> Level 4, 55 Harrington St, The Rocks NSW 2000
> PO Box H58, Australia Square, Sydney NSW 1215
>
>
>
--
*Franc Carter* | Systems architect | Sirca Ltd
<ma...@sirca.org.au>
franc.carter@sirca.org.au | www.sirca.org.au
Tel: +61 2 8355 2514
Level 4, 55 Harrington St, The Rocks NSW 2000
PO Box H58, Australia Square, Sydney NSW 1215
Re: Question about 'duplicate' columns
Posted by Aaron Morton <aa...@thelastpickle.com>.
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.
Cheers
-----------------
Aaron Morton
Cassandra Consultant
New Zealand
@aaronmorton
http://www.thelastpickle.com
On 6/08/2013, at 6:48 PM, Franc Carter <fr...@sirca.org.au> 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
> franc.carter@sirca.org.au | www.sirca.org.au
> Tel: +61 2 8355 2514
> Level 4, 55 Harrington St, The Rocks NSW 2000
> PO Box H58, Australia Square, Sydney NSW 1215
>