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From Edward Capriolo <edlinuxg...@gmail.com>
Subject Re: Retrieve all composite columns from a row, whose composite name's first component matches from a list of Integers
Date Thu, 29 Dec 2011 17:36:25 GMT
The use case in question was: Only accessing some columns.

Even if that is not the case:

SuperColumns: 1 extra level of nesting
Composite Colunns: Arbitrary levels of nesting

SuperColumns: More overhead (space on disk) then using your own delimiter '_'
SuperColumns: Likely going to be replaced in future c* version behind
the scenes by composite columns anyway
SuperColumns: Usually an afterthought for API developers, (support for
them comes "later")
SuperColumns: Almost always utilized incorrectly by users, users speak
of '10%' performance gains after they switch away from them.

There are some (a small % of cases) where SuperColumns are a better
choice, but this is rare. With composites and concatenating columns
they have no great purpose any more, (bad analogy coming!) like a
mechanical type writer.

On 12/29/11, Philippe <watcherfr@gmail.com> wrote:
> Would you stand by that statement in case all colums inside the super
> column need to be read?  Why?
>
> Thanks
> Le 28 déc. 2011 19:26, "Edward Capriolo" <edlinuxguru@gmail.com> a écrit :
>
>> Super columns have the same fundamental problem and perform worse in
>> general. So switching from composites to super columns is NEVER a good
>> idea.
>>
>>
>> On Wed, Dec 28, 2011 at 1:19 PM, Aditya <adynnn@gmail.com> wrote:
>>
>>> Since I have around 20 items to query, I guess making 20 queries to
>>> retrieve activities by all followies on all of those 20 columns would too
>>> inefficient, so to take the advantage of more efficient queries, are
>>> supercolumns recommended for this case ? Anyways, in case I use
>>> supercolumns, I need to retrieve the entire supercolumn at any point of
>>> time & I am writing subcolumn(s) to the supercolumn at different times
>>> not
>>> at once.
>>>
>>> On Wed, Dec 28, 2011 at 8:07 PM, Edward Capriolo
>>> <edlinuxguru@gmail.com>wrote:
>>>
>>>> You need to execute one get slice operation for each item id or if the
>>>> row is not large , you can try one large get slice on the entire row and
>>>> deal with the results client side.
>>>>
>>>> If you try method 1 When doing slices on composites you can set the
>>>> start inclusive or exclusive values to get only the column you want and
>>>> not
>>>> some extra columns up to slice range size.
>>>>
>>>>
>>>> On Tuesday, December 27, 2011, Aditya <adynnn@gmail.com> wrote:
>>>> > I need to store data of all activities by user's followies in single
>>>> row. I am trying to do that making use of composite column names in a
>>>> single user specific row named 'rowX'.
>>>> > On any activity by a user's followie on an item, a column is stored
in
>>>> 'rowX'. The column has a composite type column name made up of
>>>> itemId+userId (which makes it unique col. name) in rowX. (& column value
>>>> contains the activity data related to that item by that followie)
>>>> >
>>>> > Now I want to retrieve activity by all users on a list of items. So
I
>>>> need to retrieve all composite columns with composite's first component
>>>> matching the itemId. Is it possible to do such a query to Cassandra ? I
>>>> am
>>>> using Hector.
>>>>
>>>
>>>
>>
>

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