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Posted to user@cassandra.apache.org by Xu Renjie <xr...@gmail.com> on 2012/10/17 10:44:40 UTC
Astyanax empty column check
hello guys,
I am currently using Astyanax as a client(new to Astyanax). But I am not
clear how to differentiate the following 2 situations:
a. A row which has only key without columns
b. No this row in database.
Since when I use RowQuery to query Cassandra with given key, both the above
two situations will return a ColumnList
with size 0. And also I didn't find other api can handle this.
Do you have any better way for this? Thanks in advance.
Cheers,
Xu
Re: Astyanax empty column check
Posted by Xu Renjie <xr...@gmail.com>.
I see, it helps a lot. Thank you for you info.
Oh, also Mr. Joe Celko :P
On Thu, Oct 18, 2012 at 7:10 PM, aaron morton <aa...@thelastpickle.com>wrote:
> Very slim reason to link to my favourite Joe Celko (
> http://en.wikipedia.org/wiki/Joe_Celko) quote:
>
> "
> 'LOL! My wife is an ordained Soto Zen priest. I would say after 30 years
> together, I'd go with her. She is the only person who understood NULLs
> immediately.
>
> http://www.simple-talk.com/opinion/geek-of-the-week/geek-of-the-week-joe-celko/
> "
>
> a. A row which has only key without columns
>
> b. No this row in database.
>
> From the point of view of the API a row with zero *live* columns is the
> same as a row that does not exist.
>
> A row may exist on disk, but be made up of non-live columns. These are a
> combination of expired TTL columns and columns overwritten by (row or
> column) tombstones. Eventually a row with 0 live columns, with >0 non live
> columns will be compacted and purged from disk.
>
> Hope that helps.
>
>
> -----------------
> Aaron Morton
> Freelance Developer
> @aaronmorton
> http://www.thelastpickle.com
>
> On 18/10/2012, at 1:34 AM, "Hiller, Dean" <De...@nrel.gov> wrote:
>
> What specifically are you trying to achieve? The business requirement
> might help as there are other ways of solving it such that you do not need
> to know the difference.
>
> Dean
>
> From: Xu Renjie <xr...@gmail.com>
> >>
> Reply-To: "user@cassandra.apache.org<ma...@cassandra.apache.org>>"
> <us...@cassandra.apache.org>
> >>
> Date: Wednesday, October 17, 2012 4:48 AM
> To: "user@cassandra.apache.org<ma...@cassandra.apache.org>>"
> <us...@cassandra.apache.org>
> >>
> Subject: Re: Astyanax empty column check
>
> So what you mean is essentially there is *no* way to differentiate it
> because what they "appear" is the same?
>
> On Wed, Oct 17, 2012 at 5:58 PM, rohit bhatia <rohit2412@gmail.com<
> mailto:rohit2412@gmail.com <ro...@gmail.com>>> wrote:
> See
> "If you attempt to retrieve an entire row and it returns a result with
> no columns, it effectively means that row does not exist."
> Essentially a row without co
>
>
> http://stackoverflow.com/questions/8072253/is-there-a-difference-between-an-empty-key-and-a-key-that-doesnt-exist
>
> lumns doesn't exist.. (except those with tombstones)
> from here
> On Wed, Oct 17, 2012 at 2:17 PM, Xu Renjie <xrjxrjxrjnet@gmail.com<mailto:
> xrjxrjxrjnet@gmail.com>> wrote:
>
> Sorry for the version, I am using 1.0.1 Astyanax.
>
>
> On Wed, Oct 17, 2012 at 4:44 PM, Xu Renjie <xrjxrjxrjnet@gmail.com<mailto:
> xrjxrjxrjnet@gmail.com>> wrote:
>
>
> hello guys,
> I am currently using Astyanax as a client(new to Astyanax). But I am
> not clear how to differentiate the following 2 situations:
> a. A row which has only key without columns
> b. No this row in database.
>
> Since when I use RowQuery to query Cassandra with given key, both the
> above two situations will return a ColumnList
> with size 0. And also I didn't find other api can handle this.
> Do you have any better way for this? Thanks in advance.
> Cheers,
> Xu
>
>
>
>
>
>
Re: Astyanax empty column check
Posted by aaron morton <aa...@thelastpickle.com>.
Very slim reason to link to my favourite Joe Celko (http://en.wikipedia.org/wiki/Joe_Celko) quote:
"
'LOL! My wife is an ordained Soto Zen priest. I would say after 30 years together, I'd go with her. She is the only person who understood NULLs immediately.
http://www.simple-talk.com/opinion/geek-of-the-week/geek-of-the-week-joe-celko/
"
>>> a. A row which has only key without columns
>>> b. No this row in database.
From the point of view of the API a row with zero *live* columns is the same as a row that does not exist.
A row may exist on disk, but be made up of non-live columns. These are a combination of expired TTL columns and columns overwritten by (row or column) tombstones. Eventually a row with 0 live columns, with >0 non live columns will be compacted and purged from disk.
Hope that helps.
-----------------
Aaron Morton
Freelance Developer
@aaronmorton
http://www.thelastpickle.com
On 18/10/2012, at 1:34 AM, "Hiller, Dean" <De...@nrel.gov> wrote:
> What specifically are you trying to achieve? The business requirement might help as there are other ways of solving it such that you do not need to know the difference.
>
> Dean
>
> From: Xu Renjie <xr...@gmail.com>>
> Reply-To: "user@cassandra.apache.org<ma...@cassandra.apache.org>" <us...@cassandra.apache.org>>
> Date: Wednesday, October 17, 2012 4:48 AM
> To: "user@cassandra.apache.org<ma...@cassandra.apache.org>" <us...@cassandra.apache.org>>
> Subject: Re: Astyanax empty column check
>
> So what you mean is essentially there is *no* way to differentiate it because what they "appear" is the same?
>
> On Wed, Oct 17, 2012 at 5:58 PM, rohit bhatia <ro...@gmail.com>> wrote:
> See
> "If you attempt to retrieve an entire row and it returns a result with
> no columns, it effectively means that row does not exist."
> Essentially a row without co
>
> http://stackoverflow.com/questions/8072253/is-there-a-difference-between-an-empty-key-and-a-key-that-doesnt-exist
>
> lumns doesn't exist.. (except those with tombstones)
> from here
> On Wed, Oct 17, 2012 at 2:17 PM, Xu Renjie <xr...@gmail.com>> wrote:
>> Sorry for the version, I am using 1.0.1 Astyanax.
>>
>>
>> On Wed, Oct 17, 2012 at 4:44 PM, Xu Renjie <xr...@gmail.com>> wrote:
>>>
>>> hello guys,
>>> I am currently using Astyanax as a client(new to Astyanax). But I am
>>> not clear how to differentiate the following 2 situations:
>>> a. A row which has only key without columns
>>> b. No this row in database.
>>>
>>> Since when I use RowQuery to query Cassandra with given key, both the
>>> above two situations will return a ColumnList
>>> with size 0. And also I didn't find other api can handle this.
>>> Do you have any better way for this? Thanks in advance.
>>> Cheers,
>>> Xu
>>
>>
>
Re: Astyanax empty column check
Posted by "Hiller, Dean" <De...@nrel.gov>.
What specifically are you trying to achieve? The business requirement might help as there are other ways of solving it such that you do not need to know the difference.
Dean
From: Xu Renjie <xr...@gmail.com>>
Reply-To: "user@cassandra.apache.org<ma...@cassandra.apache.org>" <us...@cassandra.apache.org>>
Date: Wednesday, October 17, 2012 4:48 AM
To: "user@cassandra.apache.org<ma...@cassandra.apache.org>" <us...@cassandra.apache.org>>
Subject: Re: Astyanax empty column check
So what you mean is essentially there is *no* way to differentiate it because what they "appear" is the same?
On Wed, Oct 17, 2012 at 5:58 PM, rohit bhatia <ro...@gmail.com>> wrote:
See
"If you attempt to retrieve an entire row and it returns a result with
no columns, it effectively means that row does not exist."
Essentially a row without co
http://stackoverflow.com/questions/8072253/is-there-a-difference-between-an-empty-key-and-a-key-that-doesnt-exist
lumns doesn't exist.. (except those with tombstones)
from here
On Wed, Oct 17, 2012 at 2:17 PM, Xu Renjie <xr...@gmail.com>> wrote:
> Sorry for the version, I am using 1.0.1 Astyanax.
>
>
> On Wed, Oct 17, 2012 at 4:44 PM, Xu Renjie <xr...@gmail.com>> wrote:
>>
>> hello guys,
>> I am currently using Astyanax as a client(new to Astyanax). But I am
>> not clear how to differentiate the following 2 situations:
>> a. A row which has only key without columns
>> b. No this row in database.
>>
>> Since when I use RowQuery to query Cassandra with given key, both the
>> above two situations will return a ColumnList
>> with size 0. And also I didn't find other api can handle this.
>> Do you have any better way for this? Thanks in advance.
>> Cheers,
>> Xu
>
>
Re: Astyanax empty column check
Posted by Xu Renjie <xr...@gmail.com>.
So what you mean is essentially there is *no* way to differentiate it
because what they "appear" is the same?
On Wed, Oct 17, 2012 at 5:58 PM, rohit bhatia <ro...@gmail.com> wrote:
> See
> "If you attempt to retrieve an entire row and it returns a result with
> no columns, it effectively means that row does not exist."
> Essentially a row without co
http://stackoverflow.com/questions/8072253/is-there-a-difference-between-an-empty-key-and-a-key-that-doesnt-exist
lumns doesn't exist.. (except those with tombstones)
> from here
> On Wed, Oct 17, 2012 at 2:17 PM, Xu Renjie <xr...@gmail.com> wrote:
> > Sorry for the version, I am using 1.0.1 Astyanax.
> >
> >
> > On Wed, Oct 17, 2012 at 4:44 PM, Xu Renjie <xr...@gmail.com>
> wrote:
> >>
> >> hello guys,
> >> I am currently using Astyanax as a client(new to Astyanax). But I am
> >> not clear how to differentiate the following 2 situations:
> >> a. A row which has only key without columns
> >> b. No this row in database.
> >>
> >> Since when I use RowQuery to query Cassandra with given key, both the
> >> above two situations will return a ColumnList
> >> with size 0. And also I didn't find other api can handle this.
> >> Do you have any better way for this? Thanks in advance.
> >> Cheers,
> >> Xu
> >
> >
>
Re: Astyanax empty column check
Posted by rohit bhatia <ro...@gmail.com>.
See
"If you attempt to retrieve an entire row and it returns a result with
no columns, it effectively means that row does not exist."
Essentially a row without columns doesn't exist.. (except those with tombstones)
from here
http://stackoverflow.com/questions/8072253/is-there-a-difference-between-an-empty-key-and-a-key-that-doesnt-exist
On Wed, Oct 17, 2012 at 2:17 PM, Xu Renjie <xr...@gmail.com> wrote:
> Sorry for the version, I am using 1.0.1 Astyanax.
>
>
> On Wed, Oct 17, 2012 at 4:44 PM, Xu Renjie <xr...@gmail.com> wrote:
>>
>> hello guys,
>> I am currently using Astyanax as a client(new to Astyanax). But I am
>> not clear how to differentiate the following 2 situations:
>> a. A row which has only key without columns
>> b. No this row in database.
>>
>> Since when I use RowQuery to query Cassandra with given key, both the
>> above two situations will return a ColumnList
>> with size 0. And also I didn't find other api can handle this.
>> Do you have any better way for this? Thanks in advance.
>> Cheers,
>> Xu
>
>
Re: Astyanax empty column check
Posted by Xu Renjie <xr...@gmail.com>.
Sorry for the version, I am using 1.0.1 Astyanax.
On Wed, Oct 17, 2012 at 4:44 PM, Xu Renjie <xr...@gmail.com> wrote:
> hello guys,
> I am currently using Astyanax as a client(new to Astyanax). But I am
> not clear how to differentiate the following 2 situations:
> a. A row which has only key without columns
> b. No this row in database.
>
> Since when I use RowQuery to query Cassandra with given key, both the
> above two situations will return a ColumnList
> with size 0. And also I didn't find other api can handle this.
> Do you have any better way for this? Thanks in advance.
> Cheers,
> Xu
>