> Im finding that only the first component is used ….is this understanding
> correct?
The result is correct.
> to (end)component1=timestamp3,component2=123
is less than
> Timestamp3: 777
Example:
CREATE COLUMN FAMILY
Foo
WITH
key_validation_class = UTF8Type
AND
comparator = 'CompositeType(IntegerType, IntegerType)'
AND
default_validation_class = UTF8Type
;
set Foo['bar']['1:1'] = 'baz1';
set Foo['bar']['2:2'] = 'baz2';
set Foo['bar']['3:3'] = 'baz3';
set Foo['bar']['4:4'] = 'baz4';
aarons-MBP-2011:pycassa aaron$ ./pycassaShell -k dev
In [2]: FOO.get("bar")
Out[2]: OrderedDict([((1, 1), u'baz1'), ((2, 2), u'baz2'), ((3, 3), u'baz3'),
((4, 4), u'baz4')])
In [6]: FOO.get("bar", column_start=(2,2))
Out[6]: OrderedDict([((2, 2), u'baz2'), ((3, 3), u'baz3'), ((4, 4), u'baz4')])
In [8]: FOO.get("bar", column_start=(2,2), column_finish=(3,3))
Out[8]: OrderedDict([((2, 2), u'baz2'), ((3, 3), u'baz3')])
In [9]: FOO.get("bar", column_start=(2,2), column_finish=(3,1))
Out[9]: OrderedDict([((2, 2), u'baz2')])
In [10]: FOO.get("bar", column_start=(2,), column_finish=(3,))
Out[10]: OrderedDict([((2, 2), u'baz2'), ((3, 3), u'baz3')])
> We see a lot of examples about Timeseries modelling ...
Sorry I do not understand this question.
Cheers
-----------------
Aaron Morton
Freelance Developer
@aaronmorton
http://www.thelastpickle.com
On 24/08/2012, at 11:17 PM, Roshni Rajagopal <roshni.rajago...@wal-mart.com>
wrote:
> Thank you Aaron & Guillermo,
>
> I find composite columns very confusing :(
> To reconfirm ,
>
> 1. we can only search for columns range with the first component on the
> composite column.
> 2. After specifying a range for the first component, we cannot further
> filter for the second component. I found this link
> http://doanduyhai.wordpress.com/2012/07/05/apache-cassandra-tricks-and-traps/
> which seems to suggest filtering is possible by second component in addition
> to first, and I tried the same example but I couldn't get it to work. Does
> anyone have an example where suppose I have data like this in my column names
>
> Timestamp1: 123, Timestamp2: 456, Timestamp3: 777,Timestamp4: 654 ---get
> range of columns for (start)component1 = timestamp1, component2=123 , to
> (end)component1=timestamp3,component2=123 --> should give me only one column
> Im finding that only the first component is used ….is this understanding
> correct?
>
>
> We see a lot of examples about Timeseries modelling with TimeUUID as column
> names. But how is the updating or deletion of columns happening here, how are
> the columns found to know which ones to delete or modify. Does one always
> need a separate column family to handle updating/deletion for time series, or
> is usually handled by setting TTL for data outside the archival period, or
> does time series modelling usually not involve any manipulation of past
> records?
>
> Regards,
> Roshni
>
>
>
> From: aaron morton <aa...@thelastpickle.com<mailto:aa...@thelastpickle.com>>
> Reply-To: "user@cassandra.apache.org<mailto:user@cassandra.apache.org>"
> <user@cassandra.apache.org<mailto:user@cassandra.apache.org>>
> To: "user@cassandra.apache.org<mailto:user@cassandra.apache.org>"
> <user@cassandra.apache.org<mailto:user@cassandra.apache.org>>
> Subject: Re: Data Modelling Suggestions
>
> I was trying to find hector examples where we search for second column in a
> composite column, but I couldn't find any good one. Im not sure if its
> possible.…if you have any do have any example please share.
> It's not. When slicing columns you can only return one contiguous range.
>
> Anyway I would prefer storing the item-ids as column names in the main column
> family and having a second CF for the order-by-date query only with the pair
> timestamp_itemid. That way you can add later other query strategies without
> messing with how you store the item
> +1
> Have the orders somewhere, and build a time ordered custom index to show them
> in order.
>
> Cheers
>
> -----------------
> Aaron Morton
> Freelance Developer
> @aaronmorton
> http://www.thelastpickle.com
>
> On 24/08/2012, at 6:28 AM, Guillermo Winkler
> <gwink...@inconcertcc.com<mailto:gwink...@inconcertcc.com>> wrote:
>
> I think you need another CF as index.
>
> user_itemid -> timestamped column_name
>
> Otherwise you can't guess what's the timestamp to use in the column name.
>
> Anyway I would prefer storing the item-ids as column names in the main column
> family and having a second CF for the order-by-date query only with the pair
> timestamp_itemid. That way you can add later other query strategies without
> messing with how you store the item information.
>
> Maybe you can solve it with a secondary index by timestamp too.
>
> Guille
>
>
> On Thu, Aug 23, 2012 at 7:26 AM, Roshni Rajagopal
> <roshni.rajago...@wal-mart.com<mailto:roshni.rajago...@wal-mart.com>> wrote:
> Hi,
>
> Need some help on a data modelling question. We're using Hector & Datastax
> Enterprise 2.1.
>
>
> I want to associate a list of items for a user. It should be sorted on the
> time added. And items can be updated (quantity of the item can be changed),
> and items can be deleted.
> I can model it like this so that its denormalized and I get all my
> information in one go from one row, sorted by time added. I can use composite
> columns.
>
> Row key: User Id
> Column Name: TimeUUID:item ID: Item Name: Item Description: Item Price: Item
> Qty
> Column Value : Null
>
> Now, how do I handle manipulations
>
> 1. Add new item :Easy , just a new column
> 2. Add exiting item or modify qty: I want to get to the correct column to
> update . Can I search by second column in the composite column (equals
> condition) & update the column name itself to reflect new TimeUUID and qty?
> Or would it be better to just add it as a new column and always use the
> latest column for an item in the application code and delete duplicates in
> the background.
> 3. Delete item: Can I search by second column in the composite column to
> find the correct column to delete?
>
> I was trying to find hector examples where we search for second column in a
> composite column, but I couldn't find any good one. Im not sure if its
> possible.…if you have any do have any example please share.
>
> Regards,
> Roshni
>
>
> This email and any files transmitted with it are confidential and intended
> solely for the individual or entity to whom they are addressed. If you have
> received this email in error destroy it immediately. *** Walmart Confidential
> ***
>
>
> This email and any files transmitted with it are confidential and intended
> solely for the individual or entity to whom they are addressed. If you have
> received this email in error destroy it immediately. *** Walmart Confidential
> ***
