[jira] [Created] (CASSANDRA-6033) CQL: allow names for bind variables

["Sylvain Lebresne (JIRA)" <ji...@apache.org>]

Sylvain Lebresne created CASSANDRA-6033:
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             Summary: CQL: allow names for bind variables
                 Key: CASSANDRA-6033
                 URL: https://issues.apache.org/jira/browse/CASSANDRA-6033
             Project: Cassandra
          Issue Type: Bug
            Reporter: Sylvain Lebresne


Currently bind variables are "anonymous", they're just a question mark. What this means is that the only reliable way to reference those variables after preparation is through position their position in the query string, which is not excessively user friendly.

Of course some driver may be tempted to add their own version of named variables, but that forces said driver to parse the query string in the first place, which is something we've tried to avoid so far. Besides, this is useful enough that making it part of CQL would make this more consistent amongst driver rather than having everyone coming up with its own syntax.

I'll add that because we are already sending column names in the metadata, I believe we can support this without any change to the protocol. The idea would be to support queries like this (happy to discuss the exact syntax):
{noformat}
SELECT * FROM test WHERE key = ?my_key AND time > ?t_low AND time <= ?t_high
{noformat}

>From the Cassandra side, the only thing that this would change is that in the result set returned to the client, the column names would be 'my_key', 't_low' and 't_high' respectively rather than 'key', 'time' and 'time' as they are now.  And so in particular using an anymous variable would be equivalent to using a name one with the name of the CQL column the variable is bound to.

Driver side, the driver would just have to keep a map of each name to their position in the metadata to provide reliable setter by names.


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