<html><head></head><body style="word-wrap: break-word; -webkit-nbsp-mode: space; -webkit-line-break: after-white-space; ">I would probably say complex/fewer MR phases but I guess it would depend on the compute complexity of your functions (in order to take advantage of parallelism/more compute cores). My reasoning is that every time you Map you are reading the full value from disk. More Maps = more disk i/o. Not to mention the erlang to js overhead if you are running js functions.<div><br></div><div>Please report your findings!</div><div><br></div><div>Best,<br><div>
<span class="Apple-style-span" style="border-collapse: separate; color: rgb(0, 0, 0); font-family: Helvetica; font-style: normal; font-variant: normal; font-weight: normal; letter-spacing: normal; line-height: normal; orphans: 2; text-align: auto; text-indent: 0px; text-transform: none; white-space: normal; widows: 2; word-spacing: 0px; -webkit-border-horizontal-spacing: 0px; -webkit-border-vertical-spacing: 0px; -webkit-text-decorations-in-effect: none; -webkit-text-size-adjust: auto; -webkit-text-stroke-width: 0px; font-size: medium; "><div><br class="Apple-interchange-newline">-Alexander Sicular</div><div><br></div><div>@siculars</div></span>
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<br><div><div>On Mar 14, 2012, at 6:16 PM, Jonathan Langevin wrote:</div><br class="Apple-interchange-newline"><blockquote type="cite">What is better for performance in Riak?<div><span style="font-family:Helvetica;font-size:medium"><b><font color="#255AFC"><div><font color="#000000" face="arial"><span style="font-weight:normal;font-size:small"><span style="font-family:arial,sans-serif;font-size:13px;border-collapse:collapse">More phases with simpler logic, or less phases with more complex logic?</span></span></font></div>

<div><font color="#000000" face="arial"><span style="font-weight:normal;font-size:small"><span style="font-family:arial,sans-serif;font-size:13px;border-collapse:collapse"><br></span></span></font></div><div><font color="#000000" face="arial"><span style="font-weight:normal;font-size:small"><span style="font-family:arial,sans-serif;font-size:13px;border-collapse:collapse">For instance, if I want to check 10 different fields of the result objects, using 10 different functions, should I combine that all down into 1-2 m/r phases, or run as 10 different m/r phases?</span></span></font></div>

<div><font color="#000000" face="arial"><span style="font-weight:normal;font-size:small"><span style="font-family:arial,sans-serif;font-size:13px;border-collapse:collapse"><br></span></span></font></div><div><font color="#000000" face="arial"><span style="font-weight:normal;font-size:small"><span style="font-family:arial,sans-serif;font-size:13px;border-collapse:collapse">I would think more phases would suggest that the workload could be distributed across various nodes more easily, but few phases would mean that the values wouldn't have to be processed as many times...</span></span></font></div>

<div><font color="#000000" face="arial"><span style="font-weight:normal;font-size:small"><span style="font-family:arial,sans-serif;font-size:13px;border-collapse:collapse"><br><table border="0" cellpadding="2" cellspacing="2" width="100%">

<tbody><tr><td colspan="1" rowspan="2" valign="top" style="margin-top:0px;margin-right:0px;margin-bottom:0px;margin-left:0px;font-family:arial,sans-serif"><a href="http://www.loomlearning.com/" style="color:rgb(42,93,176)" target="_blank"><img src="http://www.loomlearning.com/loom.gif"></a><br>

</td><td valign="top" style="margin-top:0px;margin-right:0px;margin-bottom:0px;margin-left:0px;font-family:arial,sans-serif"><font face="Helvetica, Arial, sans-serif"><b><i><span style="font-family:arial;font-style:normal;font-weight:normal;font-size:small"><table border="0" cellpadding="2" cellspacing="2" width="100%" style="font-family:arial,sans-serif;font-size:13px;border-collapse:collapse">

<tbody><tr><td valign="top" style="margin-top:0px;margin-right:0px;margin-bottom:0px;margin-left:0px;font-family:arial,sans-serif"><font face="Helvetica, Arial, sans-serif"><i><b lang="sr-Latn-RS">Jonathan Langevin</b></i><br>

<font color="gray"><small>Manager, Information Technology</small></font></font><br></td></tr><tr><td valign="top" style="margin-top:0px;margin-right:0px;margin-bottom:0px;margin-left:0px;font-family:arial,sans-serif;border-top-width:1px;border-top-style:solid;border-top-color:black">

<font color="gray"><small><font face="Helvetica, Arial, sans-serif"><b>Loom Inc.</b><br>Wilmington, NC: (910) 241-0433 - <a href="mailto:jlangevin@loomlearning.com" style="color:rgb(42,93,176)" target="_blank">jlangevin@loomlearning.com</a> - <a href="http://www.loomlearning.com/" style="color:rgb(42,93,176)" target="_blank">www.loomlearning.com</a> - Skype: intel352</font></small></font></td>

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