Best way to cross matching large datasets


Posted on 16th Feb 2014 07:03 pm by admin

Hi,

Im running a script where am I cross matching about 200 000 data sets with each other. Each data set consists of 8 parameters and I want to count all datasets which have similar or the same parameters for each data set.

Right now, I am doing the matching via a MySql query which im calling about 200 000 times. The problem is that using a query is extremely expensive… it takes up to 2 hours until the script is done. So I am wondering if there is a better method to cross match data sets and if some of could help me find a better solution.

While researching I found out that arrays may be a faster alternative to queries. And so far, I identified 3 possible ways for cross matching:

1. nested foreach () loops
foreach($array as ar1)
foreach($array as ar2)
if ($ar1[0] == $ar1[0])….

2. Using an Array_map with Callback function, so that i would have only one "hand coded" loop
foreach($array as arr)
if ($arr[0] == $parameter)….

3. Array walk where i could save one "hand coded" loop as well.

Theoretically would be the best/fastest way to go about it? Can Anyone tell me what technically the difference between those 3 ways is? And which one is the better approach or if there other alternatives to them?

I am thankful for any advice that helps me reduce execution time!

No comments posted yet

Your Answer:

Login to answer
343 Like 48 Dislike
Previous forums Next forums
Other forums

BIG file upload!
Hey guys!

I'm trying to upload a file, it works well with smaller files but with 60mb+, I get

I got my hosting suspended XD
So I saw this challenge a day or so ago

http://www.programming-challenges.com/pg.php?page=dow

undefined offset help
Hi All,

I kept getting undefined offset PHP notice for a simple for loop. For eg
$va = arr

preg_match logical error
Code: <?php
$s = file_get_contents("page.html");
preg_match('/<div cla

Strange HTML Tag?
I recently noticed some odd HTML appear in some of the websites I host. Not all of them are run on a

UDS 4.0 Datatype issue
UDS 4.0.322 -- connecting to NI Labview 9.0

When using connection method: Cache with live

Problems with strings containing
Hey all,

I have encountered something strange in a script. I am trying to write an XML heade

Changes to hosting company's server has affected web contact form
I started a thread a couple of months ago about the contact forms on my client's website. Basically

big pagination problem in php
<?php

$connect = mysql_connect("localhost", "root", "")

Can I call a class inside a function?
I have a class written in another file that handles my image resizing.

Can I do this (php say

Sign up to write
Sign up now if you have flare of writing..
Login   |   Register
Follow Us
Indyaspeak @ Facebook Indyaspeak @ Twitter Indyaspeak @ Pinterest RSS



Play Free Quiz and Win Cash