On Wed, Jan 19, 2011 at 11:35 AM, Germán Kondolf <german.kond...@gmail.com>wrote:
> Yes, that's what I meant, but correct me if I'm wrong, when a deletion > comes after another deletion for the same row or column will the gc-before > count against the last one, isn't it? > > IIRC, after compaction. even if the row key is not wiped, all the CF are replaced by the youngest tombstone. I do not understand very clearly the benefit of wiping out the whole row as early as possible. > > Maybe knowing that all the subsequent versions of a deletion are deletions > too, it could take the first timestamp against the gc-grace-seconds when is > reducing & compacting. > > // Germán Kondolf > http://twitter.com/germanklf > http://code.google.com/p/seide/ > // @i4 > > On 19/01/2011, at 00:16, Jonathan Ellis <jbel...@gmail.com> wrote: > > > If you mean that multiple tombstones for the same row or column should > > be merged into a single one at compaction time, then yes, that is what > > happens. > > > > On Tue, Jan 18, 2011 at 7:53 PM, Germán Kondolf > > <german.kond...@gmail.com> wrote: > >> Maybe it could be taken into account when the compaction is executed, > >> if I only have a consecutive list of uninterrupted tombstones it could > >> only care about the first. It sounds like the-way-it-should-be, maybe > >> as a part of the "row-reduce" process. > >> > >> Is it feasible? Looking into the CASSANDRA-1074 sounds like it should. > >> > >> //GK > >> http://twitter.com/germanklf > >> http://code.google.com/p/seide/ > >> > >> On Tue, Jan 18, 2011 at 10:55 AM, Sylvain Lebresne <sylv...@riptano.com> > wrote: > >>> On Tue, Jan 18, 2011 at 2:41 PM, David Boxenhorn <da...@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 < > aa...@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 <da...@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 <r...@twitter.com> wrote: > >>>>>> > >>>>>> On Sun, Jan 16, 2011 at 6:53 AM, David Boxenhorn <da...@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? > >>>>>>> > >>>>> > >>>> > >>>> > >>> > >> > > > > > > > > -- > > Jonathan Ellis > > Project Chair, Apache Cassandra > > co-founder of Riptano, the source for professional Cassandra support > > http://riptano.com > >
