The Yet Another Related Posts Plugin algorithm

mitcho (Michael 芳貴 Erlewine)http://mitcho.com, @themitchoWordCamp Phoenix, January 29, 2011

EXPLAINED!

Over 750,000 downloads on wordpress.org! Thank you!

YARPP!

One of my favorites I just activated on my blog is called Yet Another Related Posts Plugin...

I've been blogging seven or eight years now so I have a lot of archives, and it actually surprises me sometimes when I blog about something and I visit the permalink to see I've written about it before... and it also increases the traffic on your blog because when they come in just to one entry, they'll see this other stuff going on.

Matt Mullenweg

Great features like...

Templating:• Uber-customize the related posts display

• Write templates just like for themes

http://phillprice.com http://elliottgoodman.com

The real secret to success:

The algorithm

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“THE POOL”

Taiwan travel tipsVISITORreference entry:

What’s “related”?CC-BY-NC-ND http://www.flickr.com/photos/twcollins/109069524/

The criteria:

• Title keywords*

• Content body keywords*

• Tags

• Categories

* a value computed by a MySQL FULLTEXT MATCH of the reference

entries’ top 20 keywords against the pool entries’ full values

2.73.2

1

2

SCORES:

The “match score”:A weighted sum of the criteria:

2.7 × 1 + 2.8 × 2 + 1 x 1 + 2 x 0 = 9.3

9.3 > 7 (“match threshold”) so related!

12

1

0

WEIGHTS:

tl;dr:• A good, organic sense of “relatedness”

• Default settings are pretty good :)

• Admins can see match scores to tweak

match threshold

The “relatedness” relation:

• Sometimes results in less than the specified number of results

• A feature, not a bug

• Not symmetric, not transitive

The future:

Additional criteria?Custom taxonomies, authorship, internal links...CC-BY-SA http://www.flickr.com/photos/x-ray_delta_one/4205453510/

THE QUERY

IS TOO DAMNEXPENSIVE

Smart caching:• Added in YARPP 3.0, May 2009

• Caches the “relatedness” relation

results in a custom table

Please read:Optimization tips in the FAQ

“Smart” caching:

• no need to manage it

• auto-updates on post updates, deletes

• but you can reset it if you want to:

• add &action=flush the YARPP options screen URL (version 3.2)

From cache to Loop:

• Related post display creates is own Loop

• A new WP_Query is created and hijacked

• Write code in templates like a regular

Loop, with extra template tags:

• the_score(), get_the_score()

CC-BY-NC http://www.flickr.com/photos/seadigs/5190768911/

Yet Another RelatedPosts Plugin

3.2AVAILABLE TODAY!http://tinyurl.com/yarppthreetwo

Postmeta caching

• A new caching option̶no more custom tables!

• default is still custom tables

• turn it on with:define('YARPP_CACHE_TYPE','postmeta');

YARPP 3.2:

New cache abstraction

• Cache is now a global object $yarpp_cache

• Write your own!

• Get info like $yarpp_cache->is_related($postA,$postB);

YARPP 3.2:

Thank you!slides on http://slideshare.net/mitcho

Get the latest:@themitcho, @yarpp

Yet Another Related Posts Plugin

Working hard so you can:

engage • perform • hack