7000 posts = 1 blog or more ?

WordPress isn’t the limiting factor for how many posts you can have. 7,000 posts for a mysql database is nothing…if you run into issues it will more than likely be server and/or host issues…things like the max db size your hosts will allow…for example, some limit each db to 100mb.

yes, but as things go with my blog i will have 15000 post next june… is that ok ? my db is 6 mb so that is not a problem.

Sure…I see no reason (given you have a good enough server) that you couldn’t have 15 million posts…your limit is the number of records a mysql db table can hold…I don’t know the exact number (not sure there even is an exact number), but it’s a “heck of a lot”.

Maybe some mysql guru (which I’m not one) can shed more light on this for you…

What figaro said, you are limited by your server). Not a mysql guru here, but when you reach that number of posts – remember to backup your files and database everyday with plugin or via cron (if you have cpanel) ??

To contain the posts in some way and for organizational purposes, you might want to consider using WPMU where the 2009 posts will be in blog1, 2010 posts in blog2, etc. You could create a script to export users in blog1 and import users in blog2 so you don’t have to manually create one by one. Caveat: not all single WP plugins work in WPMU.

there’s no limitation for wordpress to store post, if there were, it must’ve been located on mysql setting

but more that 10.000 posts can affect a wordpress instalation, giving errors. is likely ?

is better to have more instations with subdomains per category or 1 and big ?

but more that 10.000 posts can affect a wordpress instalation, giving errors. is likely ?

As we all said above, your WP installation growth or “health” can be limited by your server.

is better to have more instations with subdomains per category or 1 and big ?

Actually, with WPMU, in addition to installation with subdomains, you can opt for the subdirectory structure. As to whether you would stick with single WP install or go to WPMU, it’s really up to you. I mentioned some benefits above for going WPMU. But, if it’s going to be a hassle, wait till the codebases of WP and WPMU sometime in the future. You can stick with WP first and optimize your database, your theme, streamline plugins used and so forth.