Thanks for the insight into this.
---
Jeremiah Peschka - Founder, Brent Ozar Unlimited
MCITP: SQL Server 2008, MVP
Cloudera Certified Developer for Apache Hadoop
On Thu, Feb 14, 2013 at 4:40 AM, Christian Dahlqvist wrote:
> Hi OJ,
>
> The do_prereduce parameter makes it possible to have the fir
Hi OJ,
The do_prereduce parameter makes it possible to have the first iteration of the
reduce phase execute where the preceding map phase generated output. This can,
as in the example I provided, be used to reduce the amount of data that needs
to be sent across the network. This is described in
Chris,
I've never heard of do_prereduce before. What kind of effect does this
have? That is, if someone were to use it all the time, regardless of the
amount of data being returned, would this be a bad thing?
Thanks.
OJ
On Thu, Feb 14, 2013 at 6:19 PM, Christian Dahlqvist wrote:
> Hi,
>
> For b
Hi,
For buckets with a significant number of records, it makes a lot of sense to
run the example I provided with 'do_prereduce' enabled as it will result in
considerably less data being sent between the nodes. This can be enabled as
follows:
curl -XPOST http://localhost:8098/mapred
-H 'Cont
Hi Jeremiah,
It does indeed not seem to be documented on the main docs site, and I will try
to correct this. The only place I have found it described is on the wiki for
the Ruby client
(https://github.com/basho/riak-ruby-client/wiki/Secondary-Indexes).
Below is also an example of a simple map
there is no “assumption”. Right?
>
>
>
> From: Jeremiah Peschka [mailto:jeremiah.pesc...@gmail.com]
> Sent: Tuesday, February 12, 2013 1:52 PM
>
>
> To: Kevin Burton
> Cc: riak-users
> Subject: Re: ListKeys or MapReduce
>
>
>
> Oh, and an example c
Is this documented anywhere on the docs.basho.com site?
Searching for $bucket produces search results just for "bucket" and Google
says "No results found for *site:docs.basho.com $bucket*."
---
Jeremiah Peschka - Founder, Brent Ozar Unlimited
MCITP: SQL Server 2008, MVP
Cloudera Certified Develop
ah.pesc...@gmail.com]
> *Sent:* Tuesday, February 12, 2013 1:52 PM
>
> *To:* Kevin Burton
> *Cc:* riak-users
> *Subject:* Re: ListKeys or MapReduce
>
> ** **
>
> Oh, and an example can be found https://gist.github.com/peschkaj/4772825**
> **
>
>
>
>
"src/riak_api_pb_server.erl"},
>>>
>>> {line,227}]},**
>>> **
>>>
>>>
>>> {riak_api_pb_server,
>>>
>>>
y the bucket and key there is no "assumption". Right?
From: Jeremiah Peschka [mailto:jeremiah.pesc...@gmail.com]
Sent: Tuesday, February 12, 2013 1:52 PM
To: Kevin Burton
Cc: riak-users
Subject: Re: ListKeys or MapReduce
Oh, and an example can be found https://gist.github.com/p
gt;
>> {riak_api_pb_server,
>>
>> handle_info,2,***
>> *
>>
>> [{file,
>>
>>
>> "src/riak_api_pb_server.erl"},
>>
>>
handle_msg,5,
>
> [{file,
>
>
>"gen_server.erl"},
>
>
[{file,
"gen_server.erl"},
{line,607}]}] -
CommunicationError
From: riak-users [mailto:riak-users-boun...@lists.basho.com] On Behalf Of
Kevin Burton
Sent: Tuesday, Februa
(true));
RiakResult result =
riakClient.MapReduce(query);
if (result.IsSuccess)
{
From: Jeremiah Peschka [mailto:jeremiah.pesc...@gmail.com]
Sent: Tuesday, February 12, 2013 9:18 AM
To: Kevin Burton
Cc: riak-users
Subject: Re: ListKeys or MapReduce
It wou
jeremiah.pesc...@gmail.com]
> *Sent:* Tuesday, February 12, 2013 8:52 AM
> *To:* Kevin Burton
> *Cc:* riak-users
> *Subject:* Re: ListKeys or MapReduce
>
> ** **
>
> They're both pretty crappy in terms of performance - they read all data
> off of disk. If you're usi
: ListKeys or MapReduce
They're both pretty crappy in terms of performance - they read all data off
of disk. If you're using LevelDB you can use the $keys index to pull back
just the keys that in a single bucket.
A better approach is to maintain a separate bucket - e.g. DocumentCount -
th
They're both pretty crappy in terms of performance - they read all data off
of disk. If you're using LevelDB you can use the $keys index to pull back
just the keys that in a single bucket.
A better approach is to maintain a separate bucket - e.g. DocumentCount -
that is used for counting documents
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