Cassandra CLI

Cassandra CLI

Here I am not going to discuss about cassandra. A am assuming you already know cassanda and you are looking for programming issues.

Installation:

      It is so easy in windows as well ubuntu. Here all commands i tested in ubuntu  12.10 and cassandra version 1.2.1

go to the below link for download and instruction. http://cassandra.apache.org/download/

ubuntu users should follow debian installation process. In ubuntu we need to do public key authentication  You can find lot of keys in their site, but use the latest one, most of them are not working // in my case.

Programming CLI:

For testing purpose averyone will use Cassandra-cli. So here I am giving those commands and suggestions to solve issues.

Before going to this you can check below link once. http://wiki.apache.org/cassandra/CassandraCli

1. Type cassandra-cli in terinal

rajesh@rajesh-VPCEG25EN:~$ cassandra-cli Welcome to Cassandra CLI version 1.0.12 Type 'help;' or '?' for help. Type 'quit;' or 'exit;' to quit. [default@unknown]

2. connect to your cluster

connect localhost/9160;

[default@unknown] connect localhost/9160; Connected to: "Test Cluster" on localhost/9160

Note:1. In cli every command will end with semi column(“;”).

         2 . some times local host may not works you need to give your ip address instead of localhost

         3. create keyspace

3. create keyspace

 create keyspace <keyspaceName>

[default@unknown] create keyspace rajesh; 14688360-7cfd-11e2-0000-242d50cf1fbc Waiting for schema agreement... ... schemas agree across the cluster

4. use that keyspace

use <keyspaceName>

[default@unknown] use rajesh; Authenticated to keyspace: rajesh [default@rajesh]

5.create column family

create column family account1

with key_validation_class = UTF8Type

and comparator = 'AsciiType'

and default_validation_class = UTF8Type;

[default@rajesh] create column family account1 ... with key_validation_class = UTF8Type ... and comparator = 'AsciiType' ... and default_validation_class = UTF8Type; aff43210-7cfe-11e2-0000-242d50cf1fbc Waiting for schema agreement... ... schemas agree across the cluster

//In cassandra schema is optional. But we should add schema for better approach. The good thing here is you can update schema whenever you want

5.9 update column metadata

update column family address

with comparator = 'AsciiType'

and key_validation_class = 'UTF8Type'

and default_validation_class = 'UTF8Type'

and column_metadata =

[{column_name : city,

validation_class : utf8},

{column_name : zip,

validation_class : utf8}];

[default@rajesh] create column family 'users'; ce0413c0-7cfd-11e2-0000-242d50cf1fbc Waiting for schema agreement... ... schemas agree across the cluster

At initial stage I really got confused among comparator and validation classes. If you want to know about them you can find in my blog.

6. create super column family

create column family student

with column_type = 'Super'

and key_validation_class = UTF8Type

and comparator = 'AsciiType'

and default_validation_class = UTF8Type;

The only difference from column family to super column family is you need to add column type = 'super'

7.update super column metadata

update column family student

with comparator = 'AsciiType'

and key_validation_class = 'UTF8Type'

and default_validation_class = 'UTF8Type'

and column_metadata =

[{column_name : city,

validation_class : utf8},

{column_name : zip,

validation_class : utf8}];

8. insert data to column family:

set <columnfamily>['<key>']['<column name>'] = '<column value>';

[default@rajesh] set account['key117']['city'] = 'Hyderabad'; Value inserted. Elapsed time: 53 msec(s).

Note: if you get errors like below

org.apache.cassandra.db.marshal.MarshalException: cannot parse 'name' as hex bytes

If you not able to insert data then you need to add following lines

 assume <column family> keys as utf8;

//you can assume whatever you want. Eg; comparator ,validation class, ….etc

9.Insert data to super column family

set <super column family>[<key>][<super column name>][<column name>] = <value>;

[default@rajesh] set student['key1']['user1']['name']='rajesh'; Value inserted. Elapsed time: 8 msec(s).

If you get error like this

org.apache.cassandra.db.marshal.MarshalException: cannot parse 'name' as hex bytes

then you need to add few lines

assume <column family name> keys as utf8;

assume <column family name> comparator as utf8;

assume <column family name> validator as utf8;

assume <column family name> sub_comparator as utf8;

10. reading data from cassandra-cli:

if you want to read full column family use

list <column family>;

if you want to read a single key then

get <column family>[<key>];

[default@rajesh] get account[key1]; => (column=city, value=hyderabad, timestamp=1361466885159000) => (column=zip, value=5000012, timestamp=1361466900352000) Returned 2 results. Elapsed time: 88 msec(s).

This is it If you want to know any other commands type help

help;

?;

So Friend in my next post you can find java programs on cassndra. All The Best :)
//Sorry for bad alignment. As we know programmers are so lazy