Hi Ian,
I am having a problem with CQL..
For example:
CqlQuery*<String,String,Long>* cqlQuery = new CqlQuery*
<String,String,Long>*(keyspace, new StringSerializer(),new
StringSerializer(), new LongSerializer();
cqlQuery.setQuery("insert into mytable (KEY,password,gender,userid)
values (3,'pass1','male',34);");
QueryResult<CqlRows<String,String,Long>> result =
cqlQuery.execute();
This will successfully insert the row with pass1,male and 34 values under
rowId=3.
But in sling scenario, we need to have more serializers for a query as
follows. Since we have more columns.
i.e
CqlQuery*<String,String,String,String> *cqlQuery = new CqlQuery*
<String,String,String,String>*(keyspace, new StringSerializer(),new
StringSerializer(),new StringSerializer(),new StringSerializer());
cqlQuery.setQuery("insert into mytable
(KEY,path,resourceType,resourceSuperType,metadata) values
(3,'/content/cassandra/foo/bar','nt:cassandra','nt:super','metadata');
QueryResult<CqlRows<String,String,Long>> result =
cqlQuery.execute();
Here I am using me.prettyprint.cassandra.model.CqlQuery class. Any idea how
to proceed with this.
Am I doing something wring or is this a limitation of the API I am using ?
On Thu, Jun 27, 2013 at 7:41 AM, Dishara Wijewardana <
ddwijeward...@gmail.com> wrote:
>
>
> On Thu, Jun 27, 2013 at 4:26 AM, Ian Boston <i...@tfd.co.uk> wrote:
>
>> On 27 June 2013 02:34, Dishara Wijewardana <ddwijeward...@gmail.com>
>> wrote:
>>
>> > On Tue, Jun 25, 2013 at 4:52 AM, Ian Boston <i...@tfd.co.uk> wrote:
>> >
>> > > Hi,
>> > >
>> > > (I might have errors in the CQL, Cassandra schema and the functions
>> need
>> > > proper escaping)
>> > >
>> > >
>> > > Example 1:
>> > > Zero depth tree wiht UUID as the rowid or key.
>> > >
>> > > URL /content/cassandra/pictures/13f58d5c95c70b6f
>> > >
>> > > then the column family is pictures and the URL -> ROWID function just
>> > > results in the ROWID being 13f58d5c95c70b6f and
>> > >
>> > > String cql = mapOfCassandraMappers.get("pictures").getCQL("pictures",
>> "
>> > > 13f58d5c95c70b6f")
>> > > System.err.println(cql);
>> > >
>> > > where
>> > > String getCQL(String cf, String path) {
>> > > return "select * from "+cf+" where rowid = '"+path+"'";
>> > > }
>> > >
>> > > yields:
>> > > select * from pictures where rowid = '13f58d5c95c70b6f'
>> > >
>> > >
>> > > 13f58d5c95c70b6f would be generated by the application when the user
>> > > created a new picture (by upload).
>> > >
>> > >
>> > >
>> > > Example 2:
>> > > User specified
>> > >
>> > > URL
>> /content/cassandra/catalogue/capacitors/electrolytic/axial/16v/10uf
>> > >
>> > > String cql =
>> mapOfCassandraMappers.get("catalogue").getCQL("catalogue", "
>> > > capacitors/electrolytic/axial/16v/10uf")
>> > > System.err.println(cql);
>> > >
>> > > where
>> > > String getCQL(String cf, String path) {
>> > > MessageDigest md = MessageDigest.getInstance("SHA1");
>> > > String rowID = Base64.encode(md.finish(path.getBytes("UTF-8")));
>> > > return "select * from "+cf+" where rowid = '"+rowID+"'";
>> > > }
>> > >
>> > > yields
>> > >
>> > > select * from pictures where rowid = 'NzdlZmU4OTZmNGM4MzMwYzZ'
>> > >
>> > > If you want to find the parent then
>> > >
>> > > mapOfCassandraMappers.get("catalogue").getCQL("catalogue", "
>> > > capacitors/electrolytic/axial/16v")
>> > >
>> > > select * from pictures where rowid = 'ZGFzZGZzZnNkYWZzYWRmc2R'
>> > >
>> > > And if the parent is stored in the property parent then
>> > >
>> > > select * from pictures where parent = 'ZGFzZGZzZnNkYWZzYWRmc2R'
>> > >
>> > > will generate a list of children. (Not sure about performance)
>> > >
>> > >
>> > > Example 3:
>> > > User is allowed to enter the RowID directly (identical to Example 1
>> > > URL
>> > >
>> > >
>> >
>> /content/cassandra/cannesfilmfestival/TomCruiseCassino-20130402112345-ieb.jpg
>> > >
>> > > where
>> > > String getCQL(String cf, String path) {
>> > > return "select * from "+cf+" where rowid = '"+path+"'";
>> > > }
>> > >
>> > > yields:
>> > > select * from pictures where rowid = '
>> > > TomCruiseCassino-20130402112345-ieb.jpg'
>> > >
>> >
>> > This should be corrected as
>> > select * from cannesfilmfestival where rowid = '
>> > TomCruiseCassino-20130402112345-ieb.jpg'
>> >
>> >
>> > >
>> > >
>> > > Does that make sense ?
>> > >
>> >
>>
>> Hi
>>
>>
>> > Hi Ian,
>> > I was in fact practicing some cql stuff in related to this response
>> (with
>> > cassandra cql terminal). This is quite a wonderful explanation for a new
>> > comer like me. Thank you very much for the explanation again. Now it
>> really
>> > makes sense.
>> >
>>
>> excellent!
>>
>>
>> >
>> > Other than the zero depth approach, I believe users will be more
>> > comfortable with Example 2 approach.
>> > Shall we go ahead with it ?
>> >
>>
>>
>> Yes, go for it. It will be interesting to see how hard it is to implement
>> and how well (or not) it works. Remember, keep it as simple as possible
>> and
>> dont try and and cover every use case at the expense of getting a PoC
>> working.
>>
> +1.
>
>>
>> However, dont forget, Unit tests mocked with Mockito are a quicker way of
>> getting to working code, than no unit test coverage.
>>
>> Best Regards
>> Ian
>>
>>
>>
>>
>> >
>> >
>> > > Ian
>> > >
>> > >
>> > >
>> > >
>> > > On 25 June 2013 05:29, Dishara Wijewardana <ddwijeward...@gmail.com>
>> > > wrote:
>> > >
>> > > > On Mon, Jun 24, 2013 at 4:02 AM, Ian Boston <i...@tfd.co.uk> wrote:
>> > > >
>> > > > > Hi Dishara,
>> > > > > Yes. 1 resource == 1 row.
>> > > > > The columns within that row represent the properties of the
>> resource.
>> > > > > I suggest that you use standard property names where appropriate
>> (eg
>> > > > > sling:resourceType is the Resource.resourceType etc)
>> > > > >
>> > > > > The Resource itself should be adaptable to a generic
>> > CassandraResource
>> > > > > (which will probably implement Resource) which will have a map of
>> > > > > properties containing all the columns of the cassandra row.
>> (optimise
>> > > > > later) A CassandraResource might look and feel like a Map<String,
>> > > Object>
>> > > > > or it might have a Map<String, Object> getProperties() method, or
>> > > better
>> > > > > still be adaptable to a Map. The essential think is dont hard code
>> > the
>> > > > > property names in the interface of CassandraResource for the
>> moment.
>> > ie
>> > > > no
>> > > > > getContentType() and no getMimeType(), as we dont really know
>> what a
>> > > > > CassandraResource will store.
>> > > > >
>> > > > > ResourceMetadata should be built from a subset of the
>> > CassandraResource
>> > > > > properties.
>> > > > >
>> > > > > You won't need to implement a ResourceResolver, only a
>> > ResourceProvider
>> > > > > (and Factory). I would use CQL in preference to other API methods.
>> > > > >
>> > > > > There is one thing that hasnt been mentioned, and thats the URL ->
>> > > > > Cassandra Row mapping.
>> > > > > There are several ways of doing this.
>> > > > >
>> > > > > eg:
>> > > > > URL = /content/cassandra/<columnFamily>/<rowID>
>> > > > > Cassandra Column Family = columnFamily
>> > > > > Cassandra RowID = rowID
>> > > > > or
>> > > > > URL =
>> /content/cassandra/<columnFamilySelector>/remainder/of/the/path
>> > > > > Cassandra Cassandra Column Family =
>> > > > > mapOfColumnFamilies.get(columnFamilySelector)
>> > > > > Cassandra RowID = function(/remainder/of/the/path)
>> > > > >
>> > > > > or to take that one stage further
>> > > > >
>> > > > > public interface CassandraMapper {
>> > > > > String getCQL(String columnFamilySelector, String path);
>> > > > > }
>> > > > >
>> > > > Hi Ian
>> > > > Thank you for the detailed explanation.
>> > > >
>> > > > OK. +1 for this approach with the mentioned flexibility.But I need
>> a
>> > > small
>> > > > clarification. With this approach,
>> > > >
>> > > > URL = /content/cassandra/<columnFamilySelector>ROW-ID
>> > > > ROW-ID - function(/remainder/of/the/path).
>> > > > So you mean ROW-ID is something we have to programatically uniquely
>> > > create
>> > > > right ? like a UUID.
>> > > >
>> > > > What is this "/remainder/of/the/path" means ? Can you give an
>> example
>> > > with
>> > > > real values in the context of a user who want to obtain a resource
>> from
>> > > > cassandra.
>> > > > This is just for my understanding.
>> > > >
>> > > >
>> > > >
>> > > > >
>> > > > > URL = /content/cassandra/<columnFamilySelector>/<remainderOfPath>
>> > > > >
>> > > > > String cqlQuery =
>> > > > >
>> > > > >
>> > > >
>> > >
>> >
>> mapOfCassandraMappers.get(columnFamilySelector).getCQL(columnFamilySelector,
>> > > > > remainderOfPath);
>> > > > >
>> > > > > Which would allow us provided one or more implementations of
>> > > > > CassandraMapper to map between URL and CQL.
>> > > > >
>> > > > >
>> > > > > HTH
>> > > > > Ian
>> > > > >
>> > > > >
>> > > > >
>> > > > >
>> > > > >
>> > > > >
>> > > > >
>> > > > >
>> > > > >
>> > > > >
>> > > > >
>> > > > >
>> > > > >
>> > > > >
>> > > > >
>> > > > >
>> > > > > On 23 June 2013 19:29, Dishara Wijewardana <
>> ddwijeward...@gmail.com>
>> > > > > wrote:
>> > > > >
>> > > > > > Hi Ian,
>> > > > > >
>> > > > > > What is the data mapping should be between Cassandra and Sling
>> > > > resource.
>> > > > > I
>> > > > > > mean is a Sling Resource maps to a Cassandra Column ? Or Column
>> > > Family
>> > > > ?
>> > > > > >
>> > > > > > Because to get this Cassandra and Sling story correct we need to
>> > > > finalize
>> > > > > > this.
>> > > > > > For an example what we eventually returns is a Sling resource.
>> > > > Everything
>> > > > > > that needs to fill in to create Sling resource should be stored
>> in
>> > > > > > Cassandra.
>> > > > > > In a Sling resource,
>> > > > > >
>> > > > > > - Path - direct sling resource path
>> > > > > > - ResourceType - nt:cassandra
>> > > > > > - ResourceSuperType - ?
>> > > > > > - ResourceMetadata - we can create this on the fly with the
>> data
>> > > > from
>> > > > > > the corresponding column. At insertion, those need to be
>> stored.
>> > > > > > Following
>> > > > > > are the ones which I thought might be useful by default to be
>> > set
>> > > > for
>> > > > > > any
>> > > > > > node. Please add if we need anything more.
>> > > > > > - ContentType
>> > > > > > - ContentLength
>> > > > > > - CreationTime
>> > > > > > - ModificationTime
>> > > > > > - ResourceResolver - Do we need a resolver in this case ?
>> > > > > >
>> > > > > >
>> > > > > > So I believe in CQL context, one ROW should represent a Sling
>> > > > resource.
>> > > > > If
>> > > > > > that is the case for ResourceMetadata we might need a separate
>> > column
>> > > > to
>> > > > > > store it since it has multiple values. I am not sure whether we
>> can
>> > > do
>> > > > it
>> > > > > > with CQL, but it should be possible with hector APIs may be.
>> > > > > >
>> > > > > > Appreciate your thoughts ?
>> > > > > >
>> > > > > >
>> > > > > > On Wed, Jun 19, 2013 at 1:19 AM, Dishara Wijewardana <
>> > > > > > ddwijeward...@gmail.com> wrote:
>> > > > > >
>> > > > > > > Hi Ian,
>> > > > > > > I am starting this thread to keep track on things related to
>> the
>> > > GSoC
>> > > > > > > project related milestone status updates and related
>> discussions.
>> > > > > > > So the first task over view will be as follows as per GSoC
>> > proposal
>> > > > > > > provided.
>> > > > > > >
>> > > > > > > 1. Implementing a CassandraResourceProvider to READ from
>> > > Cassandra.
>> > > > > > > Implementation Details [1]
>> > > > > > >
>> > > > > > >
>> > > > > > >
>> > > > > > > [1] : Implementation Details:
>> > > > > > >
>> > > > > > > 1.A) Write a CassanrdaResourceProviderUtil which is
>> basically a
>> > > > > > > cassendra client which will facilitate all cassandra related
>> > > > operations
>> > > > > > > required by other modules (CassandraResourceProvider and
>> > > > > > > CassandraResourceResolver).
>> > > > > > >
>> > > > > > > 1.B) Implementation of CassandraResourceProvider
>> > > > > > >
>> > > > > > > 1.C) Implementation of CassandraResourceResolver
>> > > > > > >
>> > > > > > > 1.D) Implementation of CassandraResource
>> > > > > > >
>> > > > > > >
>> > > > > > > And I will start writing the CassanrdaResourceProviderUtil
>> class
>> > > > which
>> > > > > > > will do basic add and get using hector API. Please provide any
>> > > > feedback
>> > > > > > > that will be useful to accomplish this task.
>> > > > > > > So for this how does path mapping should be done. Because for
>> > > > example,
>> > > > > > the
>> > > > > > > path of the cassendra node will not be same as the jcr node
>> path.
>> > > i.e
>> > > > > > > provider will ask a node path /system/myapps/test/foo and
>> where
>> > > > should
>> > > > > we
>> > > > > > > return it from Cassandra. Aren't we have to first consider the
>> > > WRITE
>> > > > > > aspect
>> > > > > > > to Cassandra ?
>> > > > > > >
>> > > > > > >
>> > > > > > > --
>> > > > > > > Thanks
>> > > > > > > /Dishara
>> > > > > > >
>> > > > > >
>> > > > > >
>> > > > > >
>> > > > > > --
>> > > > > > Thanks
>> > > > > > /Dishara
>> > > > > >
>> > > > >
>> > > >
>> > > >
>> > > >
>> > > > --
>> > > > Thanks
>> > > > /Dishara
>> > > >
>> > >
>> >
>> >
>> >
>> > --
>> > Thanks
>> > /Dishara
>> >
>>
>
>
>
> --
> Thanks
> /Dishara
>
--
Thanks
/Dishara
