But actually %postname% does not cause performance issues like other “text elements” in the permalink. Since WP 2.6 or so, it's no longer issue (= post_id and postname are the same, performance-wise). And yeah, I'm staying away from category in the permalink nowadays, mainly for it making the URL too long for my taste and I like the post_id short-URL possibility too.

But actually %postname% does not cause performance issues like other “text elements” in the permalink. Since WP 2.6 or so, it's no longer issue (= post_id and postname are the same, performance-wise). And yeah, I'm staying away from category in the permalink nowadays, mainly for it making the URL too long for my taste and I like the post_id short-URL possibility too.

Using just the post name as the permalink is the most recommended option for search engine optimization, so that is an excellent option. The downside with that is that after sometime you might run into possibility of duplicate URLs that you have to manage by hand.

There is another reason to use post-id in the starting of the permalink, WordPress documentation (http://codex.wordpress.org/Permalinks) strongly recommends not to use text fields (like %postname% or %category%) in the starting of permalink structure for performance reasons regarding database, instead it suggests to use a numeric field in the beginning (like %post_id%).

Including year/date in the permalink discourages the user to read the article giving the impression of being outdated.

One more possible reason to include post_id (and use it instead of year/month/date etc) is that if one is planning to submit his site to Google news in the future, it requires to have a 3 or more digits identifier in the URL (and that should not be year/month/date), post_id serves that purpose well.

Now about including Category,

Also, for example WordPress warns about possible performance issues using category in the permalink.

WordPress do not warn to include category in the permalink, it only recommends not to put it at the beginning of permalink.

But still, including category in the permalink has some drawbacks:

1. Modifying categories later breaks permalinks, as you mentioned.
2. Adding categories increases length of permalinks.
3. If the category being used in permalink is nested, the URL becomes too long. e.g. example.com/12345/internet/blogging/wordpress/best-permalink-structure/
4. If the article is having more than one category, the category is chosen randomly based on lower category-id. So, you may not include category of your choice in the URL and later if you add another category to post, the permalink can change.
5. The “/” at the end mimics a directory which a post is not.

Most people use category just because it add some more keywords in the permalink, keeping in mind the above drawbacks, this benefit is negligible. One can easily compensate for it by adding the extra keywords to post slug. That is, the above permalink can be example.com/12345/wordpress-best-permalink-structure/

So I agree with you, the best option is %postid%/%postname%

If you, or anyone else do decide to change permalink structure, just make sure to set 301 redirects right away (I use Redirection -plugin, but it didn't pick up permalink change automatically, like it does when individual posts change). In theory, WordPress is already indexing your posts with %postname%, so it might redirect automatically, but I'd still set 301's.

And if you've manually linked to posts internally (as you should) it's better to updated those links as well, to avoid unnecessary redirects (for this editing I used Search Regex -plugin). – So in short, switching permalink structure on the fly is advanced stuff. Proceed with caution :)

If you, or anyone else do decide to change permalink structure, just make sure to set 301 redirects right away (I use Redirection -plugin, but it didn't pick up permalink change automatically, like it does when individual posts change). In theory, WordPress is already indexing your posts with %postname%, so it might redirect automatically, but I'd still set 301's.

And if you've manually linked to posts internally (as you should) it's better to updated those links as well, to avoid unnecessary redirects (for this editing I used Search Regex -plugin). – So in short, switching permalink structure on the fly is advanced stuff. Proceed with caution :)

I am using just the postname.

I have read somewhere that wordpress automatically notice if a new post has the same title as another one. It then changes the url to example-article-2 för example. So unique URL:s should not be a problem.

is it true ? i still learning :(

It’s bad for performance, because WP doesn’t know if the link is a folder, page, post or such, and it takes it longer to find the actual page. Plus WP has to store more data to it’s database to keep track of all the pages (this is one reason why some have bloated wp_options table in the Db)).

If the permalink starts with a number (e.g. year or post ID), WP immediately knows it’s a post and can proceed faster.

All in One SEO pack doesn’t affect permalinks, but it’s great help for search engine optimization e.g. by optimizing the title tag which is the most important on-page SEO factor.

I think the one thing that has helped me is using the All in one SEO with every post. I wasn’t at first but lately I have gotten to where I do it with every post and I have noticed an improvement to the traffic I am getting.
.-= Patty Reiser’s last blog ..Tuesday’s Digital Tutorial #6 =-.

Everything in a content management system, which WordPress and many other blogging platforms are, everything in the database has unique identifier. That’s the way for the dynamic system to find what it’s looking for.