Re: SSTable Ancestors information in Cassandra 3.0.x

[Rajath Subramanyam]

Thanks Jeff.


Rajath Subramanyam


On Thu, Mar 23, 2017 at 4:50 PM, Jeff Jirsa  wrote:

> The ancestors were used primarily to clean up leftovers in the case that
> cassandra was killed right as compaction finished, where the
> source/origin/ancestors were still on the disk at the same time as the
> compaction result.
>
> It's not timestamp based, though - that compaction process has moved to
> using a transaction log, which tracks the source/results on a per
> compaction basis, and cassandra uses those logs/journals rather than
> inspecting the ancestors.
>
> - Jeff
>
>
>
> On Thu, Mar 23, 2017 at 4:35 PM, Rajath Subramanyam 
> wrote:
>
> > Thanks, Jeff. Did all the internal tasks and the compaction tasks move
> to a
> > timestamp-based approach?
> >
> > Regards,
> > Rajath
> >
> > 
> > Rajath Subramanyam
> >
> >
> > On Thu, Mar 23, 2017 at 2:12 PM, Jeff Jirsa  wrote:
> >
> > > That information was removed, because it was really meant to be used
> for
> > a
> > > handful of internal tasks, most of which were no longer used. The
> > remaining
> > > use was cleaning up compaction leftovers, and the compaction leftover
> > code
> > > was rewritten in 3.0 / CASSANDRA-7066 (note, though, that it's somewhat
> > > incomplete in the upgrade case , so CASSANDRA-13313 may be interesting
> to
> > > people who are very very very very very very very sensitive to data
> > > consistency)
> > >
> > >
> > > On Thu, Mar 23, 2017 at 2:00 PM, Rajath Subramanyam <
> rajat...@gmail.com>
> > > wrote:
> > >
> > > > Hello Cassandra-Users and Cassandra-dev,
> > > >
> > > > One of the handy features in sstablemetadata that was part of
> Cassandra
> > > > 2.1.15 was that it displayed Ancestor information of an SSTable. Here
> > is
> > > a
> > > > sample output of the sstablemetadata tool with the ancestors
> > information
> > > in
> > > > C* 2.1.15:
> > > > [centos@chen-datos test1-b83746000fef11e7bdfc8bb2d6662df7]$
> > > > sstablemetadata
> > > > ks3-test1-ka-2-Statistics.db | grep "Ancestors"
> > > > Ancestors: [1]
> > > > [centos@chen-datos test1-b83746000fef11e7bdfc8bb2d6662df7]$
> > > >
> > > > However, the same tool in Cassandra 3.0.x no longer gives us that
> > > > information. Here is a sample output of the sstablemetadata grepping
> > for
> > > > Ancestors information in C* 3.0 (the output is empty since it is no
> > > longer
> > > > available):
> > > > [centos@rj-cassandra-1 elsevier1-ab7389f0fafb11e6ac23e7ccf62f494b]$
> > > > sstablemetadata mc-5-big-Statistics.db | grep "Ancestors"
> > > > [centos@rj-cassandra-1 elsevier1-ab7389f0fafb11e6ac23e7ccf62f494b]$
> > > >
> > > > My question, how can I get this information in C* 3.0.x ?
> > > >
> > > > Thank you !
> > > >
> > > > Regards,
> > > > Rajath
> > > >
> > > > 
> > > > Rajath Subramanyam
> > > >
> > >
> >
>

Re: SSTable Ancestors information in Cassandra 3.0.x

[Jeff Jirsa]

The ancestors were used primarily to clean up leftovers in the case that
cassandra was killed right as compaction finished, where the
source/origin/ancestors were still on the disk at the same time as the
compaction result.

It's not timestamp based, though - that compaction process has moved to
using a transaction log, which tracks the source/results on a per
compaction basis, and cassandra uses those logs/journals rather than
inspecting the ancestors.

- Jeff



On Thu, Mar 23, 2017 at 4:35 PM, Rajath Subramanyam 
wrote:

> Thanks, Jeff. Did all the internal tasks and the compaction tasks move to a
> timestamp-based approach?
>
> Regards,
> Rajath
>
> 
> Rajath Subramanyam
>
>
> On Thu, Mar 23, 2017 at 2:12 PM, Jeff Jirsa  wrote:
>
> > That information was removed, because it was really meant to be used for
> a
> > handful of internal tasks, most of which were no longer used. The
> remaining
> > use was cleaning up compaction leftovers, and the compaction leftover
> code
> > was rewritten in 3.0 / CASSANDRA-7066 (note, though, that it's somewhat
> > incomplete in the upgrade case , so CASSANDRA-13313 may be interesting to
> > people who are very very very very very very very sensitive to data
> > consistency)
> >
> >
> > On Thu, Mar 23, 2017 at 2:00 PM, Rajath Subramanyam 
> > wrote:
> >
> > > Hello Cassandra-Users and Cassandra-dev,
> > >
> > > One of the handy features in sstablemetadata that was part of Cassandra
> > > 2.1.15 was that it displayed Ancestor information of an SSTable. Here
> is
> > a
> > > sample output of the sstablemetadata tool with the ancestors
> information
> > in
> > > C* 2.1.15:
> > > [centos@chen-datos test1-b83746000fef11e7bdfc8bb2d6662df7]$
> > > sstablemetadata
> > > ks3-test1-ka-2-Statistics.db | grep "Ancestors"
> > > Ancestors: [1]
> > > [centos@chen-datos test1-b83746000fef11e7bdfc8bb2d6662df7]$
> > >
> > > However, the same tool in Cassandra 3.0.x no longer gives us that
> > > information. Here is a sample output of the sstablemetadata grepping
> for
> > > Ancestors information in C* 3.0 (the output is empty since it is no
> > longer
> > > available):
> > > [centos@rj-cassandra-1 elsevier1-ab7389f0fafb11e6ac23e7ccf62f494b]$
> > > sstablemetadata mc-5-big-Statistics.db | grep "Ancestors"
> > > [centos@rj-cassandra-1 elsevier1-ab7389f0fafb11e6ac23e7ccf62f494b]$
> > >
> > > My question, how can I get this information in C* 3.0.x ?
> > >
> > > Thank you !
> > >
> > > Regards,
> > > Rajath
> > >
> > > 
> > > Rajath Subramanyam
> > >
> >
>

Re: SSTable Ancestors information in Cassandra 3.0.x

[Rajath Subramanyam]

Thanks, Jeff. Did all the internal tasks and the compaction tasks move to a
timestamp-based approach?

Regards,
Rajath


Rajath Subramanyam


On Thu, Mar 23, 2017 at 2:12 PM, Jeff Jirsa  wrote:

> That information was removed, because it was really meant to be used for a
> handful of internal tasks, most of which were no longer used. The remaining
> use was cleaning up compaction leftovers, and the compaction leftover code
> was rewritten in 3.0 / CASSANDRA-7066 (note, though, that it's somewhat
> incomplete in the upgrade case , so CASSANDRA-13313 may be interesting to
> people who are very very very very very very very sensitive to data
> consistency)
>
>
> On Thu, Mar 23, 2017 at 2:00 PM, Rajath Subramanyam 
> wrote:
>
> > Hello Cassandra-Users and Cassandra-dev,
> >
> > One of the handy features in sstablemetadata that was part of Cassandra
> > 2.1.15 was that it displayed Ancestor information of an SSTable. Here is
> a
> > sample output of the sstablemetadata tool with the ancestors information
> in
> > C* 2.1.15:
> > [centos@chen-datos test1-b83746000fef11e7bdfc8bb2d6662df7]$
> > sstablemetadata
> > ks3-test1-ka-2-Statistics.db | grep "Ancestors"
> > Ancestors: [1]
> > [centos@chen-datos test1-b83746000fef11e7bdfc8bb2d6662df7]$
> >
> > However, the same tool in Cassandra 3.0.x no longer gives us that
> > information. Here is a sample output of the sstablemetadata grepping for
> > Ancestors information in C* 3.0 (the output is empty since it is no
> longer
> > available):
> > [centos@rj-cassandra-1 elsevier1-ab7389f0fafb11e6ac23e7ccf62f494b]$
> > sstablemetadata mc-5-big-Statistics.db | grep "Ancestors"
> > [centos@rj-cassandra-1 elsevier1-ab7389f0fafb11e6ac23e7ccf62f494b]$
> >
> > My question, how can I get this information in C* 3.0.x ?
> >
> > Thank you !
> >
> > Regards,
> > Rajath
> >
> > 
> > Rajath Subramanyam
> >
>

Re: SSTable Ancestors information in Cassandra 3.0.x

[Jeff Jirsa]

That information was removed, because it was really meant to be used for a
handful of internal tasks, most of which were no longer used. The remaining
use was cleaning up compaction leftovers, and the compaction leftover code
was rewritten in 3.0 / CASSANDRA-7066 (note, though, that it's somewhat
incomplete in the upgrade case , so CASSANDRA-13313 may be interesting to
people who are very very very very very very very sensitive to data
consistency)


On Thu, Mar 23, 2017 at 2:00 PM, Rajath Subramanyam 
wrote:

> Hello Cassandra-Users and Cassandra-dev,
>
> One of the handy features in sstablemetadata that was part of Cassandra
> 2.1.15 was that it displayed Ancestor information of an SSTable. Here is a
> sample output of the sstablemetadata tool with the ancestors information in
> C* 2.1.15:
> [centos@chen-datos test1-b83746000fef11e7bdfc8bb2d6662df7]$
> sstablemetadata
> ks3-test1-ka-2-Statistics.db | grep "Ancestors"
> Ancestors: [1]
> [centos@chen-datos test1-b83746000fef11e7bdfc8bb2d6662df7]$
>
> However, the same tool in Cassandra 3.0.x no longer gives us that
> information. Here is a sample output of the sstablemetadata grepping for
> Ancestors information in C* 3.0 (the output is empty since it is no longer
> available):
> [centos@rj-cassandra-1 elsevier1-ab7389f0fafb11e6ac23e7ccf62f494b]$
> sstablemetadata mc-5-big-Statistics.db | grep "Ancestors"
> [centos@rj-cassandra-1 elsevier1-ab7389f0fafb11e6ac23e7ccf62f494b]$
>
> My question, how can I get this information in C* 3.0.x ?
>
> Thank you !
>
> Regards,
> Rajath
>
> 
> Rajath Subramanyam
>