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From Wayne Schroeder <wschroe...@pinsightmedia.com>
Subject Re: Caching prepared queries and different consistency levels
Date Fri, 28 Feb 2014 18:44:28 GMT
Well, it may seem like I'm talking to myself now with this response, but I cracked open the
source and found the answer in fairly short order so I figured I would share what I found.
 Datastax folks, please do verify that I'm correct if you don't mind.

Long story short, BoundStatement initializes from the PreparedStatement's consistency, and
that's where it stops -- it is not connected to the original PreparedStatement.  The thing
I have to be careful about is changing the consistency level of the PreparedStatement's that
I am caching as it will effectively change the default of ONE that I am expecting.  This is
obviously specific to my application, but hopefully it helps anyone who has followed that
pattern as well.

Wayne


On Feb 28, 2014, at 12:18 PM, Wayne Schroeder <wschroeder@pinsightmedia.com>
 wrote:

> After upgrading to the 2.0 driver branch, I received a lot of warnings about re-preparing
previously prepared statements.  I read about this issue, and my work around was to cache
my prepared statements in a Map<String, PreparedStatement> internally in my app via
a common prepare method, where the string key was the CQL query itself.  This has been working
perfectly, but I realized today that the consistency level I was setting on BoundStatement
is actually inherited from Statement.  Now, while it is obviously not the same object instance
(the BoundStatement vs the cached PreparedStatement), I was concerned that I was inadvertently
changing the consistency level of the cached PreparedStatement in a non thread safe fashion.
 My impression had been that the BoundStatement, even though created against a cached/shared
PreparedStatement, was mine to do with what I pleased exclusively in my thread context.  Is
this a correct/incorrect assumption?
> 
> I guess what it boils down to is the following:   Are the consistency level in the PreparedStatement
and BoundStatement linked when the BoundStatement is created so that modifying the consistency
level of the BoundStatement modifies the underlying PreparedStatement?
> 
> What I am hoping is the case is that the PreparedStatement's consistency level is just
used to initialize the BoundStatement and that the BoundStatement's consistency level is then
used when executing the query.
> 
> Wayne
> 


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