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Date: Tue, 17 Sep 2013 22:33:52 +0000 (UTC)
From: "Jonathan Ellis (JIRA)" <jira@apache.org>
To: commits@cassandra.apache.org
Message-ID: <JIRA.12668796.1379347130718.150357.1379457232962@arcas>
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Subject: [jira] [Commented] (CASSANDRA-6033) CQL: allow names for bind
 variables
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    [ https://issues.apache.org/jira/browse/CASSANDRA-6033?page=3Dcom.atlas=
sian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=3D=
13770089#comment-13770089 ]=20

Jonathan Ellis commented on CASSANDRA-6033:
-------------------------------------------

=08I've already wished for this a few times, but to play devil's advocate, =
isn't it a bit late to change this now that we have multiple drivers in pro=
duction?  I submit that users have already made their peace with this.
               =20
> 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. W=
hat this means is that the only reliable way to reference those variables a=
fter preparation is through position their position in the query string, wh=
ich is not excessively user friendly.
> Of course some driver may be tempted to add their own version of named va=
riables, 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 us=
eful enough that making it part of CQL would make this more consistent amon=
gst 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 ide=
a would be to support queries like this (happy to discuss the exact syntax)=
:
> {noformat}
> SELECT * FROM test WHERE key =3D ?my_key AND time > ?t_low AND time <=3D =
?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 equi=
valent 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 the=
ir position in the metadata to provide reliable setter by names.

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