“range key” is formally known as “clustering column”. One or more clustering
columns can be specified to identify individual rows in a partition. Without
clustering columns, one partition is one row. So, it’s a matter of whether you
want your rows to be in the same partition or distributed.
-- Jack Krupansky
From: Laing, Michael
Sent: Thursday, March 13, 2014 1:39 PM
To: user@cassandra.apache.org
Subject: Re: CQL Select Map using an IN relationship
Think of them as:
PRIMARY KEY (partition_key[, range_key])
where the partition_key can be compounded as:
(partition_key0 [, partition_key1, ...])
and the optional range_key can be compounded as:
range_key0 [, range_key1 ...]
If you do this: PRIMARY KEY (key1, key2) - then key1 is the partition_key and
key2 is the range_key and queries will work that hash to key1 (the partition)
using = or IN and specify a range on key2.
But if you do this: PRIMARY key ((key1, key2)) then (key1, key2) is the
compound partition key - there is no range key - and you can specify = on key1
and = or IN on key2 (but not a range).
Anyway that's what I remember! Hope it helps.
ml
On Thu, Mar 13, 2014 at 11:27 AM, David Savage <davemssav...@gmail.com> wrote:
Great that works, thx! I probably would have never found that...
It now makes me wonder in general when to use PRIMARY KEY (key1, key2) or
PRIMARY KEY ((key1, key2)), any examples would be welcome if you have the time.
Kind regards,
Dave
On Thu, Mar 13, 2014 at 2:56 PM, Laing, Michael <michael.la...@nytimes.com>
wrote:
Create your table like this and it will work:
CREATE TABLE test.documents (group text,id bigint,data
map<text,text>,PRIMARY KEY ((group, id)));
The extra parens catenate 'group' and 'id' into the partition key - IN will
work on the last component of a partition key.
ml
On Thu, Mar 13, 2014 at 10:40 AM, David Savage <davemssav...@gmail.com>
wrote:
Nope, upgraded to 2.0.5 and still get the same problem, I actually
simplified the problem a little in my first post, there's a composite primary
key involved as I need to partition ids into groups
So the full CQL statements are:
CREATE KEYSPACE test WITH replication = {'class':'SimpleStrategy',
'replication_factor':3};
CREATE TABLE test.documents (group text,id bigint,data
map<text,text>,PRIMARY KEY (group, id));
INSERT INTO test.documents(id,group,data) VALUES (0,'test',{'count':'0'});
INSERT INTO test.documents(id,group,data) VALUES (1,'test',{'count':'1'});
INSERT INTO test.documents(id,group,data) VALUES (2,'test',{'count':'2'});
SELECT id,data FROM test.documents WHERE group='test' AND id IN (0,1,2);
Thanks for your help.
Kind regards,
/Dave
On Thu, Mar 13, 2014 at 2:00 PM, David Savage <davemssav...@gmail.com>
wrote:
Hmmm that maybe the problem, I'm currently testing with 2.0.2 which got
dragged in by the cassandra unit library I'm using for testing [1] I will try
to fix my build dependencies and retry, thx.
/Dave
[1] https://github.com/jsevellec/cassandra-unit
On Thu, Mar 13, 2014 at 1:56 PM, Laing, Michael
<michael.la...@nytimes.com> wrote:
I have no problem doing this w 2.0.5 - what version of C* are you
using? Or maybe I don't understand your data model... attach 'creates' if you
don't mind.
ml
On Thu, Mar 13, 2014 at 9:24 AM, David Savage
<davemssav...@gmail.com> wrote:
Hi Peter,
Thanks for the help, unfortunately I'm not sure that's the problem,
the id is the primary key on the documents table and the timestamp is the
primary key on the eventlog table
Kind regards,
Dave
On Thursday, 13 March 2014, Peter Lin <wool...@gmail.com> wrote:
it's not clear to me if your "id" column is the KEY or just a
regular column with secondary index.
queries that have IN on non primary key columns isn't supported
yet. not sure if that answers your question.
On Thu, Mar 13, 2014 at 7:12 AM, David Savage
<davemssav...@gmail.com> wrote:
Hi there,
I'm experimenting using cassandra and have run across an error
message which I need a little more information on.
The use case I'm experimenting with is a series of document
updates (documents being an arbitrary map of key value pairs), I would like to
find the latest document updates after a specified time period. I don't want to
store many copies of the documents (one per update) as the updates are often
only to single keys in the map so that would involve a lot of duplicated data.
The solution I've found that seems to fit best in terms of
performance is to have two tables.
One that has an event log of timeuuid -> docid and a second
that stores the documents themselves stored by docid -> map<string, string>. I
then run two queries, one to select ids that have changed after a certain time:
SELECT id FROM eventlog WHERE
timestamp>=minTimeuuid($minimumTime)
and then a second to select the actual documents themselves
SELECT id, data FROM documents WHERE id IN (0, 1, 2, 3, 4, 5,
6, 7…)
However this then explodes on query with the error message:
"Cannot restrict PRIMARY KEY part id by IN relation as a
collection is selected by the query"
Detective work lead me to these lines in
org.apache.cassandra.cql3.statementsSelectStatement:
// We only support IN for the last name and
for compact storage so far
// TODO: #3885 allows us to extend to non
compact as well, but that remains to be done
if (i != stmt.columnRestrictions.length - 1)
throw new
InvalidRequestException(String.format("PRIMARY KEY part %s cannot be restricted
by IN relation", cname));
else if (stmt.selectACollection())
throw new
InvalidRequestException(String.format("Cannot restrict PRIMARY KEY part %s by
IN relation as a collection is selected by the query", cname));
It seems like #3885 will allow support for the first IF block
above, but I don't think it will allow the second, am I correct?
Any pointers on how I can work around this would be greatly
appreciated.
Kind regards,
Dave
