Re: Backports to 2.1.16

[sankalp kohli]

We dont plan to open them at this time considering 2.1 is pretty old.

On Fri, Oct 21, 2016 at 3:02 AM, Romain Hardouin <
romainh...@yahoo.fr.invalid> wrote:

> Interesting, will you publish the backports on https://github.com/apple ?
>
>
>
> Thanks,
>
> Romain
>

[GitHub] cassandra pull request #78: Fix flapping test in 2.0.17. Looks like an event...

[earlye]

Github user earlye closed the pull request at:

https://github.com/apache/cassandra/pull/78


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[GitHub] cassandra issue #78: Fix flapping test in 2.0.17. Looks like an eventual con...

[earlye]

Github user earlye commented on the issue:

https://github.com/apache/cassandra/pull/78
  
Didn't notice I was submitting to this repo & branch. Not my intent.


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[GitHub] cassandra pull request #78: Fix flapping test in 2.0.17. Looks like an event...

[earlye]

GitHub user earlye opened a pull request:

https://github.com/apache/cassandra/pull/78

Fix flapping test in 2.0.17. Looks like an eventual consistency issue.

Not the best fix - would prefer to have a way to have the test wait until 
it knows the 6 INSERTs ahead of checking the results had completed instead.

You can merge this pull request into a Git repository by running:

$ git pull https://github.com/keenlabs/cassandra 
earlye-fix-cass2.0.17-flapping-test

Alternatively you can review and apply these changes as the patch at:

https://github.com/apache/cassandra/pull/78.patch

To close this pull request, make a commit to your master/trunk branch
with (at least) the following in the commit message:

This closes #78


commit 88b77fe54cd895a8f15815dc4b813b2041acaaae
Author: Early Ehlinger 
Date:   2016-10-21T14:41:39Z

Fix flapping test in 2.0.17. Looks like an eventual consistency issue.




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Re: Backports to 2.1.16

[Romain Hardouin]

Interesting, will you publish the backports on https://github.com/apple ?



Thanks,

Romain

Re: Is SASI index in Cassandra efficient for high cardinality columns?

[DuyHai Doan]

If you read my blog post about 2nd index deep dive, you'll get all the
answers
Le 21 oct. 2016 10:20, "Kant Kodali"  a écrit :

> Why Secondary index cannot be broken down into token ranges like primary
> index at least for exact matches? That way dont need to scan the whole
> cluster atleast for exact matches. I understand if it is a substring search
> then there will 2^n substrings which equates to 2^n hashes/tokens which can
> be a lot!
>
> On Sat, Oct 15, 2016 at 4:35 AM, DuyHai Doan  wrote:
>
> > If each indexed value has very few matching rows, then querying using
> SASI
> > (or any impl of secondary index) may scan the whole cluster.
> >
> > This is because the index are "distributed" e.g. the indexed values stay
> > on the same nodes as the base data. And even SASI with its own
> > data-structure will not help much here.
> >
> > One should understand that the 2nd index query has to deal with 2 layers:
> >
> > 1) The cluster layer, which is common for any impl of 2nd index. Read my
> > blog post here: http://www.planetcassandra.org/blog/
> > cassandra-native-secondary-index-deep-dive/
> >
> > 2) The local read path, which depends on the impl of 2nd index. Some are
> > using Lucene library like Stratio impl, some rolls in its own data
> > structures like SASI
> >
> > If you have a 1-to-1 relationship between the index value and the
> matching
> > row (or 1-to-a few), I would recommend using materialized views instead:
> >
> > http://www.slideshare.net/doanduyhai/sasi-cassandra-on-
> > the-full-text-search-ride-voxxed-daybelgrade-2016/25
> >
> > Materialized views guarantee that for each search indexed value, you only
> > hit a single node (or N replicas depending on the used consistency level)
> >
> > However, materialized views have their own drawbacks (weeker consistency
> > guarantee) and you can't use range queries (<,  >, ≤, ≥) or full text
> > search on the indexed value
> >
> >
> >
> >
> >
> > On Sat, Oct 15, 2016 at 11:55 AM, Kant Kodali  wrote:
> >
> >> Well I went with the definition from wikipedia and that definition rules
> >> out #1 so it is #2 and it is just one matching row in my case.
> >>
> >>
> >>
> >> On Sat, Oct 15, 2016 at 2:40 AM, DuyHai Doan 
> >> wrote:
> >>
> >> > Define precisely what you mean by "high cardinality columns". Do you
> >> mean:
> >> >
> >> > 1) a single indexed value is present in a lot of rows
> >> > 2) a single indexed value has only a few (if not just one) matching
> row
> >> >
> >> >
> >> > On Sat, Oct 15, 2016 at 8:37 AM, Kant Kodali 
> wrote:
> >> >
> >> >> I understand Secondary Indexes in general are inefficient on high
> >> >> cardinality columns but since SASI is built from scratch I wonder if
> >> the
> >> >> same argument applies there? If not, Why? Because I believe primary
> >> keys in
> >> >> Cassandra are indeed indexed and since Primary key is supposed to be
> >> the
> >> >> column with highest cardinality why not do the same for secondary
> >> indexes?
> >> >>
> >> >
> >> >
> >>
> >
> >
>

Re: Is SASI index in Cassandra efficient for high cardinality columns?

[Kant Kodali]

Why Secondary index cannot be broken down into token ranges like primary
index at least for exact matches? That way dont need to scan the whole
cluster atleast for exact matches. I understand if it is a substring search
then there will 2^n substrings which equates to 2^n hashes/tokens which can
be a lot!

On Sat, Oct 15, 2016 at 4:35 AM, DuyHai Doan  wrote:

> If each indexed value has very few matching rows, then querying using SASI
> (or any impl of secondary index) may scan the whole cluster.
>
> This is because the index are "distributed" e.g. the indexed values stay
> on the same nodes as the base data. And even SASI with its own
> data-structure will not help much here.
>
> One should understand that the 2nd index query has to deal with 2 layers:
>
> 1) The cluster layer, which is common for any impl of 2nd index. Read my
> blog post here: http://www.planetcassandra.org/blog/
> cassandra-native-secondary-index-deep-dive/
>
> 2) The local read path, which depends on the impl of 2nd index. Some are
> using Lucene library like Stratio impl, some rolls in its own data
> structures like SASI
>
> If you have a 1-to-1 relationship between the index value and the matching
> row (or 1-to-a few), I would recommend using materialized views instead:
>
> http://www.slideshare.net/doanduyhai/sasi-cassandra-on-
> the-full-text-search-ride-voxxed-daybelgrade-2016/25
>
> Materialized views guarantee that for each search indexed value, you only
> hit a single node (or N replicas depending on the used consistency level)
>
> However, materialized views have their own drawbacks (weeker consistency
> guarantee) and you can't use range queries (<,  >, ≤, ≥) or full text
> search on the indexed value
>
>
>
>
>
> On Sat, Oct 15, 2016 at 11:55 AM, Kant Kodali  wrote:
>
>> Well I went with the definition from wikipedia and that definition rules
>> out #1 so it is #2 and it is just one matching row in my case.
>>
>>
>>
>> On Sat, Oct 15, 2016 at 2:40 AM, DuyHai Doan 
>> wrote:
>>
>> > Define precisely what you mean by "high cardinality columns". Do you
>> mean:
>> >
>> > 1) a single indexed value is present in a lot of rows
>> > 2) a single indexed value has only a few (if not just one) matching row
>> >
>> >
>> > On Sat, Oct 15, 2016 at 8:37 AM, Kant Kodali  wrote:
>> >
>> >> I understand Secondary Indexes in general are inefficient on high
>> >> cardinality columns but since SASI is built from scratch I wonder if
>> the
>> >> same argument applies there? If not, Why? Because I believe primary
>> keys in
>> >> Cassandra are indeed indexed and since Primary key is supposed to be
>> the
>> >> column with highest cardinality why not do the same for secondary
>> indexes?
>> >>
>> >
>> >
>>
>
>