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From "Brandon Williams (JIRA)" <j...@apache.org>
Subject [jira] [Commented] (CASSANDRA-5437) multiget specific key filtering
Date Mon, 08 Apr 2013 19:25:16 GMT

    [ https://issues.apache.org/jira/browse/CASSANDRA-5437?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13625699#comment-13625699
] 

Brandon Williams commented on CASSANDRA-5437:
---------------------------------------------

There is a third option, and it's the best: perform gets and parallelize them yourself.  Here's
why: if you perform a multiget on [x,y,z] keys and x and y are fine, but z times out, all
you get is an exception.  If you had done parallel gets yourself, you'd have gotten x and
y, then retried z, but since you used multiget now you have to retry the entire query again.

That said, I don't think we have any plans to change or improve the thrift interface at this
point.
                
> multiget specific key filtering
> -------------------------------
>
>                 Key: CASSANDRA-5437
>                 URL: https://issues.apache.org/jira/browse/CASSANDRA-5437
>             Project: Cassandra
>          Issue Type: Improvement
>            Reporter: Brooke Bryan
>            Priority: Minor
>
> Currently, you are able to specify a list of columns, or a slice when pulling back keys
from a multiget, however, we find ourselves pulling back a lot more data than we actually
need when columns overlap.  We currently have 2 options (as far as im aware).
> 1. perform multiple get calls, and get the required data back, but connect to thrift
more
> 2. perform a multiget, and get more data due to column crossovers, but in a single request.
> Similar to a batch mutation, a batch read would solve this problem perfectly.
> e.g.
> read = [
>   'columnFamily' => [
>     'key' => ColumnPath,
>     'key2' => SlicePredicate,
>     'key3' => ColumnPath
>   ]
> ];
> result = batch_read(read);
> //result
> 'columnFamily' => [
>     'key' => [1 => 'a',2 => 'b',3 => 'c'],
>     'key2' => [4 => 'd',5 => 'e'],
>     'key3' => [1 => 'a',3 => 'c']
>   ]

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