incubator-cassandra-user mailing list archives

Site index · List index
Message view « Date » · « Thread »
Top « Date » · « Thread »
From Xu Renjie <xrjxrjxrj...@gmail.com>
Subject Re: Astyanax empty column check
Date Fri, 19 Oct 2012 11:24:42 GMT
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 <aaron@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" <Dean.Hiller@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 <xrjxrjxrjnet@gmail.com<mailto:xrjxrjxrjnet@gmail.com<xrjxrjxrjnet@gmail.com>
> >>
> Reply-To: "user@cassandra.apache.org<mailto:user@cassandra.apache.org<user@cassandra.apache.org>>"
> <user@cassandra.apache.org<mailto:user@cassandra.apache.org<user@cassandra.apache.org>
> >>
> Date: Wednesday, October 17, 2012 4:48 AM
> To: "user@cassandra.apache.org<mailto:user@cassandra.apache.org<user@cassandra.apache.org>>"
> <user@cassandra.apache.org<mailto:user@cassandra.apache.org<user@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 <rohit2412@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
>
>
>
>
>
>

Mime
View raw message