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From "Laing, Michael" <michael.la...@nytimes.com>
Subject Re: Deleting column names
Date Tue, 22 Apr 2014 16:05:18 GMT
Your understanding is incorrect - the easiest way to see that is to try it.


On Tue, Apr 22, 2014 at 12:00 PM, Sebastian Schmidt <isibboi@gmail.com>wrote:

> From my understanding, this would delete all entries with the given s.
> Meaning, if I have inserted (sa, p1, o1, c1) and (sa, p2, o2, c2),
> executing this:
>
> DELETE FROM table_name WHERE s = sa AND p = p1 AND o = o1 AND c = c1
>
> would delete sa, p1, o1, c1, p2, o2, c2. Is this correct? Or does the
> above statement only delete p1, o1, c1?
>
>
> 2014-04-22 4:00 GMT+02:00 Steven A Robenalt <srobenal@stanford.edu>:
>
> Is there a reason you can't use:
>>
>> DELETE FROM table_name WHERE s = ? AND p = ? AND o = ? AND c = ?;
>>
>>
>> On Mon, Apr 21, 2014 at 6:51 PM, Eric Plowe <eric.plowe@gmail.com> wrote:
>>
>>> Also I don't think you can null out columns that are part of the primary
>>> key after they've been set.
>>>
>>>
>>> On Monday, April 21, 2014, Andreas Wagner <
>>> andreas.josef.wagner@googlemail.com> wrote:
>>>
>>>> Hi cassandra users, hi Sebastian,
>>>>
>>>> I'd be interested in this ... is there any update/solution?
>>>>
>>>> Thanks so much ;)
>>>> Andreas
>>>>
>>>> On 04/16/2014 11:43 AM, Sebastian Schmidt wrote:
>>>>
>>>>> Hi,
>>>>>
>>>>> I'm using a Cassandra table to store some data. I created the table
>>>>> like
>>>>> this:
>>>>> CREATE TABLE IF NOT EXISTS table_name (s BLOB, p BLOB, o BLOB, c BLOB,
>>>>> PRIMARY KEY (s, p, o, c));
>>>>>
>>>>> I need the at least the p column to be sorted, so that I can use it in
>>>>> a
>>>>> WHERE clause. So as far as I understand, the s column is now the row
>>>>> key, and (p, o, c) is the column name.
>>>>>
>>>>> I tried to delete single entries with a prepared statement like this:
>>>>> DELETE p, o, c FROM table_name WHERE s = ? AND p = ? AND o = ? AND c
=
>>>>> ?;
>>>>>
>>>>> That didn't work, because p is a primary key part. It failed during
>>>>> preparation.
>>>>>
>>>>> I also tried to use variables like this:
>>>>> DELETE ?, ?, ? FROM table_name WHERE s = ?;
>>>>>
>>>>> This also failed during preparation, because ? is an unknown
>>>>> identifier.
>>>>>
>>>>>
>>>>> Since I have multiple different p, o, c combinations per s, deleting
>>>>> the
>>>>> whole row identified by s is no option. So how can I delete a s, p, o,
>>>>> c
>>>>> tuple, without deleting other s, p, o, c tuples with the same s? I know
>>>>> that this worked with Thrift/Hector before.
>>>>>
>>>>> Regards,
>>>>> Sebastian
>>>>>
>>>>
>>>>
>>
>>
>> --
>> Steve Robenalt
>> Software Architect
>>  HighWire | Stanford University
>> 425 Broadway St, Redwood City, CA 94063
>>
>> srobenal@stanford.edu
>> http://highwire.stanford.edu
>>
>>
>>
>>
>>
>>
>

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