Cassandra (CQL) select statement with 'where' is not working

Question

I am using Cassandra last few days. I am using PHPCassa library for that. When I am trying to use the following code, Its not working correctly. ``` require_once('phpcassa/connection.php'); require_once "phpcassa/columnfamily.php"; // Create new ConnectionPool like you normally would $pool = new ConnectionPool("newtest"); // Retrieve a raw connection from the ConnectionPool $raw = $pool->get(); $rows = $raw->client->execute_cql_query("SELECT * FROM User WHERE KEY='phpqa'", cassandra_Compression::NONE); echo "

"; print_r($rows); echo ""; // Return the connection to the pool so it may be used by other callers. Otherwise, // the connection will be unavailable for use. $pool->return_connection($raw); unset($raw); ``` Its returning nothing, I have also tried following queries ``` $rows = $raw->client->execute_cql_query("SELECT * FROM User WHERE age='32'", cassandra_Compression::NONE); $rows = $raw->client->execute_cql_query("SELECT * FROM User WHERE name='jack'", cassandra_Compres…

Accepted Answer

In cassandra you cant just query a 'table' as you would normally. You need to set up secondary indexes for every column you might want to query.

Say we have a table:

```
 key      | User |   Age 
----------+----------------
 phpqa    | Jack |   20    
```

You can query directly on the key:

```
SELECT * FROM User WHERE key='phpqa';
```

But to carry out other WHERE queries you'd need a secondary index on the columns you want to have available in the WHERE clause.

What can you do to make your querying flexible in the way that you desire:

- Secondary indexes as described above.

- Use composite columns as your key. Its a good idea if you only have 2-3 columns you want to query, but have a read through this article detailing how and when to use composite keys, and here is a link in how to implement it in phpcassa.

Cassandra (CQL) select statement with 'where' is not working

Solution

Problem