Ok seems that i'll use Solr (with dedicated Cassandra) for search

I've readed this article : http://ria101.wordpress.com/2010/02/22/cassandra-randompartitioner-vs-orderpreservingpartitioner/ on RP vs OPP... 


Here is my case


docs_shared{ //docs shared by users ordered by time
    'time:id_user:id_doc' 
    {
        'time':'123456' //index on it
        'id_user':'123' //index on it
        'c_type':'BOT' //index on it
        'id_doc':'123' //index on it      
    }

So i can list all doc shared by id_user = 123 and type ='BOT' ordered by time....

Well i wanted because i discovered the RP vs OPP issue. I'm default so RP and so row id are not ordered !!! And as it's recommanded, i would like to stay RP

So other possibility is addind a dimension with super column as column are ordered in RP

index{
docs_shared{ //docs shared by users ordered by time
    'time:id_user:id_doc' 
    {
        'time':'123456' //index on it
        'id_user':'123' //index on it
        'c_type':'BOT' //index on it
        'id_doc':'123' 
    }
}

BUT.... sexondary index is not possible on SC -> C


So next possibility is

index{
docs_shared_time_c_type_id_user{ //docs shared by users ordered by time:c_type:id_user
    'time:c_type:id_user:id_doc' : 'id_doc'
docs_shared_c_type_time_id_user{ //docs shared by users ordered by time:id_user:c_type
    'c_type:time:id_user:id_do' : 'id_doc'
... (there is 6 combinations of time c_type id_user)
}

Like that i can list with keystart and keyend and filters

Example :

No filter : index -> time:c_type:id_user
Filter on c_type :  index -> c_type:time:id_user
Filter on id_user :  index -> id_user:time:c_type
Filter on c_type and id_user : index -> id_user:c_type:time

Fortunately cassandra likes writing !!! (Ironic inside)


So i have a question : i've readed that secondary index on SC->C will maybe arrive in next releases... Is this information true ? And is it already planned ?


Thank you,

Sébastien,

2011/3/2 Burc Sade <burcsade@gmail.com>
You can use PHP Solr Extension. It is a fully featured and light-weight client.

http://www.php.net/manual/en/book.solr.php

Without the secondary indexes on columns in CFs within SCFs, the best approach is to create query-specific CFs at the moment. In the end all comes down to how simple you can make your queries to have a minimum CF count.

Regards,
Burc

On Wed, Mar 2, 2011 at 9:06 AM, Vodnok <vodnok@gmail.com> wrote:
I think too via Solr it'll be easier. Just need to google it. (if you have links about Solr in php...)

I realize that i have to remove some dimension to my CF...

I thought it was possible to have SCF -> CF -> SC -> C:value having secondary index on C but has i understood, secondary index on C on super is not possible for now (but will be maybe in next version)
As i understand it's better to have more less complex CF then less more complex CF

Thank you for your reply,



2011/3/2 Burc Sade <burcsade@gmail.com>

Hi Vodnok,

For tag searches I would use a search engine like Solr (Lucene), as I think it would be more flexible to query. You can update the index as new data comes in and query it for queries #1, #2 and #4.

For "All doc of type='BOT' and c_bot_code='ABC'" query, I would create the CF below.

doc_types
{
   'BOT:ABC':
  {
    <docid>: <creation_date?> 
  } 
}

You can assign a value you are going to need when after querying to the docid. The problem with this schema is that if there are not many type:c_bot_code combinations, there will be many columns under each key in this CF. If a combination has much much more columns than others, hot spot problem may arise.



On Tue, Mar 1, 2011 at 11:39 PM, Vodnok <vodnok@gmail.com> wrote:
Hi,

Totaly newbie on Cassandra (with phpcassa) with big background on relationned database, i'm would like to use Cassandra for a trivial case. So i'm on it since 3 days. Sorry for my stupid question. I'm pretty sure i'm wrong but i want to learn so i'm here


I would like your advise on a design for cassandra.


Case:

- Users created Docs and can share docs with friends
- Users can read and share docs of their friends with other friends
- Docs can be of different type [text;picture;video;etc]
- Docs can be taggued



Typical queries :


- Doc relative to tag
- Doc relative to mutiple tags
- Doc readed by user x
- Doc relative to tag and ratio readed_shared greater than x (see design)
- All doc of type='IMG' favorized by my friend
- All doc of type='BOT' and c_bot_code='ABC'
- All doc of type='BOT' favorized by my friend relative (tag) with 'fire' and 'belgium' ?



Design :


docs // all docs
{
    ‘123456’: //id_docs
    {
        ‘t_info’: 
{
'c_type':'BOT'
'b_del':'y'
'b_publish':'y'
}
't_info_type':
{
'l_title':'Hello World!'
'c_bot_code':'ABC'
}
't_read_user' : //read by user x
{
//time + id_user
'123456789_123':'123'
'123456789_155':'155'
}
't_shared_user' : //share by user x
{
//time + id_user
'123456789_123':'123'
'123456789_155':'155'
}
't_tags'
{
'fire':'fire'
'belgium':'belgium'
}
't_stats'
{
'n_readed':'60'
'n_shared':'6'
'n_ratio_readed_shared':'0.1'
}
}
}


tags_docs // all tag linked to docs
{
'fire'://tag
{
//creation_time + id_docs
'456789_123456':
{
'id_doc':'123456'
'time':'456789'
}
'456789_223456':'223456':
{
'id_doc':'123456'
'time':'456789'
}
'456789_323456':'223456':
{
'id_doc':'123456'
'time':'456789'
}
}
'belgium':
{
...
}
}


users // all users
{
    ‘123’: //id_user
    {
        ‘t_info’: 
{
l_name:'Boris'
c_lang='fr'

}
't_readed_docs':
{
//time + id_doc
'123456789_123456':'123456'
'123458789_136456':'136456'
}
't_shared_docs':
{
//time + id_doc
'123456789_123456':'123456'
'123458789_136456':'136456'
}
}
}


users_docs // all action by users on docs
{
    ‘123_123456’: // id_user + id_doc
    {
'id_doc':'123456'
'id_user':'123'
'd_readed':'20110301'
'd_shared':'20110301'
}
}


user_friends_act // all activity of user friends
{
    ‘123’:// id_user
    {
't_readed_docs': //all docs readed by my friends
{
'223456_224_123456': // time + id_friend + id_docs
{
'id_friend':'224'
'id_docs':'123456'
'time':'223456'
'c_type='BOT'
}
}
't_shared_docs': //all docs shared by my friends
{
'223456_224_123456': // time + id_friend + id_docs
{
'id_friend':'224'
'id_docs':'123456'
'time':'223456'
'c_type='BOT'
}
}
}
}



I know that certain queries are not possible for now like : - All doc of type='BOT' favorized by my friend relative (tag) with 'fire' and 'belgium' ?



What do you think ?


Thank you,


Vodnok,


(Please remember i'm on cassandra since 3 days)