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Date: Tue, 13 Jul 2010 08:47:13 -0400
Message-ID: <AANLkTik2A7BRwuRwuuuMb3uRuFIx9SkK0RTx-zKiC6az@mail.gmail.com>
Subject: Re: Question regarding consistency and deletion
From: Samuru Jackson <samurujackson@googlemail.com>
To: user@cassandra.apache.org
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Thanks for the links.

Actually it is pretty easy to catch those tombstoned keys on the
client side. However, in certain applications it can generate some
additional overhead on the network.

I think it would be nice to have a forced garbage collection in the
API. This would IMHO ease to write Unit-Tests.

/SJ

On Mon, Jul 12, 2010 at 6:34 PM, Aaron Morton <aaron@thelastpickle.com> wro=
te:
> The Tomstones are removed after GCGraceSeconds (in the storage-config.xml=
),
> at the next Major Compaction
> http://wiki.apache.org/cassandra/MemtableSSTable?highlight=3D%28tombstone=
s%29
>
> Take a look at http://wiki.apache.org/cassandra/DistributedDeletes=A0 and
> Handling Failure on http://wiki.apache.org/cassandra/Operations
>
> This one explains the internal reason the tombstoned keys are returned
> http://wiki.apache.org/cassandra/FAQ#range_ghosts
>
> You could reduce the GCGraceSeconds. Others may have a better idea how to
> force it.
>
> Aaron
> On 13 Jul, 2010,at 03:17 AM, Samuru Jackson <samurujackson@googlemail.com=
>
> wrote:
>
> Hi,
>
> I'm fairly new to Cassandra and started to set up a small cluster for
> playing around and evaluating it for my potential purposes.
>
> As far as I understand I can't remove whole rows - instead the columns
> of a deleted rows are removed and a client can decided based on the
> row's column count if it treats a part of a returned slice as deleted
> or not. Those empty rows are referenced as a Tombstone in Cassandras
> terminology- right?
>
> Is there any way to force the sync/garbage collection of the deletion
> of the such empty rows?
>
> Reading the mailinglist, this behaviour is relating to the weak
> consistency of Cassandra. What I don't understand is, why is it
> possible to remove the columns of a row, but not the whole row? Could
> you give me some further reading on this topic?
>
> Thanks!
>
> SJ
>