Hello all,
I am curious about how many records one MySQL database can handle(with PHP as a frontend)?
I am tryin to make a search engine with over 500 000 records in one single table..here is it: http://www.findthis.info
But as you will notice on the first search it takes up to 5-6 seconds to return results then every other search after the first is very fast...is it about the large MySQL database,or this has nothing to do,and it's up to my PHP scripts???
Thanks alot in advance!

You might look into optimizing your code, or checking the capabilities of the server you're on. 500,000 records is nothing for a MySQL database... depending on what types of info you're storing. And have you created an index on that table? That can greatly increase search speeds.

Also, to answer your other question, a MySQL database can [theoretically] hold approximately 64 terabytes of data as of 3.23 with the MyISAM storage engine. Up to and including version 3.22 had a limit of 4 GB imposed:
http://dev.mysql.com/doc/refman/4.1/en/table-size.html
http://dev.mysql.com/doc/refman/5.1/en/table-size.html

moved to database...

I will agree with keith on what has been said. indexes can do wonders when running queries.

Thanks for your answers...I also think it depends mostly on the hardware on which the site is running.But about indexes as far as I know the index is needed only for modifying the data, but not for searching however I am still not sure that an index can speed up the search process.I tried adding and index auto_increment but it was the same.Anyway I am talking about 5-6 seconds ;)) "slow" not about several minutes waiting..so it's hard to say :)

No no, we're not talking auto-incrementing IDs. We're talking indexes, such as a full-text index.

This tutorial will give you a pretty good understanding of how to set up and take advantage of a full-text index:
http://www.phpfreaks.com/tutorials/129/