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!

Your Answer:

Login to answer

Other forums

=> and <=
So I was digging through some code when I came across the <= operator. This is the first tim

PHP mail() returns true but doesn't work
First off I apologize if this is a newbie question, and I generally don't like asking questions that

Login Control?!
I have a Web Site that uses the login control also I have set the destinationurl to the page I want

Custom array sort? asc then desc
Any ideas how I could sort this array? I've been trying for a while. Maybe with usort, but I have no

Help! refer to a friend script with captcha code
Hi guys, I am posting on here in desperate need for some help with an ongoing search I have been doi

extract content from a website
i have written a code that will grab the content from the index page..
i would like to know how c

PHP Programming error. Please help!
Hi there,

Am making a website for a friend and have encountered a problem that i need fixing

Calling variables
I want to call this to my website but it doesn't display what I want it to,

Code: <h5&

1,000 select boxes with 100 options?!
I have 1 drop down select box with 1,000 options.


In some case, there will be 100+ of the

Displaying different page content, depending on the logged in user.
Hi all, I am new to ASP.net (and web development in general), and have a question about how I can di