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From David Boxenhorn <da...@lookin2.com>
Subject Re: Tombstone lifespan after multiple deletions
Date Tue, 18 Jan 2011 13:58:54 GMT
Thanks.

On Tue, Jan 18, 2011 at 3:55 PM, Sylvain Lebresne <sylvain@riptano.com>wrote:

> On Tue, Jan 18, 2011 at 2:41 PM, David Boxenhorn <david@lookin2.com>
> wrote:
> > Thanks, Aaron, but I'm not 100% clear.
> >
> > My situation is this: My use case spins off rows (not columns) that I no
> > longer need and want to delete. It is possible that these rows were never
> > created in the first place, or were already deleted. This is a very large
> > cleanup task that normally deletes a lot of rows, and the last thing that
> I
> > want to do is create tombstones for rows that didn't exist in the first
> > place, or lengthen the life on disk of tombstones of rows that are
> already
> > deleted.
> >
> > So the question is: before I delete, do I have to retrieve the row to see
> if
> > it exists in the first place?
>
> Yes, in your situation you do.
>
> >
> >
> >
> > On Tue, Jan 18, 2011 at 11:38 AM, Aaron Morton <aaron@thelastpickle.com>
> > wrote:
> >>
> >> AFAIK that's not necessary, there is no need to worry about previous
> >> deletes. You can delete stuff that does not even exist, neither
> batch_mutate
> >> or remove are going to throw an error.
> >> All the columns that were (roughly speaking) present at your first
> >> deletion will be available for GC at the end of the first tombstones
> life.
> >> Same for the second.
> >> Say you were to write a col between the two deletes with the same name
> as
> >> one present at the start. The first version of the col is avail for GC
> after
> >> tombstone 1, and the second after tombstone 2.
> >> Hope that helps
> >> Aaron
> >> On 18/01/2011, at 9:37 PM, David Boxenhorn <david@lookin2.com> wrote:
> >>
> >> Thanks. In other words, before I delete something, I should check to see
> >> whether it exists as a live row in the first place.
> >>
> >> On Tue, Jan 18, 2011 at 9:24 AM, Ryan King <ryan@twitter.com> wrote:
> >>>
> >>> On Sun, Jan 16, 2011 at 6:53 AM, David Boxenhorn <david@lookin2.com>
> >>> wrote:
> >>> > If I delete a row, and later on delete it again, before
> GCGraceSeconds
> >>> > has
> >>> > elapsed, does the tombstone live longer?
> >>>
> >>> Each delete is a new tombstone, which should answer your question.
> >>>
> >>> -ryan
> >>>
> >>> > In other words, if I have the following scenario:
> >>> >
> >>> > GCGraceSeconds = 10 days
> >>> > On day 1 I delete a row
> >>> > On day 5 I delete the row again
> >>> >
> >>> > Will the tombstone be removed on day 10 or day 15?
> >>> >
> >>
> >
> >
>

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