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

Why does first ever HttpSendRequest take longer?
I promise this isn't as simple as it sounds. I'm wondering why the the first ever call to HttpSendRe

Quick Syntax Question
Hi folks,

I'm getting the following error: "unexpected T_LNUMBER". I'm trying to b

big pagination problem in php
<?php

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

how to get IP address?
hey guys,

i have this code which is supposed to get me the IP address of my site visitors:

PHP referral database. I would like this form to email the referrer.
Okay, Hello I've been trolling for years. This the first time I've ever asked for php help. Normally

LIMIT $start, 10... how to pass last value queried into next page with GET??
Ok I know how to display the first or last 10 results of a query...

$result = mysql_query(&q

URL Rewrite issue
Im created a series of Rewrites and on page checks to make sure the correct url is being called. But

SCO Unix
I know this might not be the place to ask, but, can anyone tell me if SCO Unix comes with PHP built

question about stripslashes and real_escape_string
im cleaning up an old app that I wrote fixing some of the vulernabilities from attacks.

I hav

PDO returns erroneous columns from within pdt
Hi All,

This is a truly weird behavior:
When using a simple pdo fetch, erroneous columns a