That does make sense, John. What Philip is saying is that you might run into problems with one of the tables used to keep track of tables and databases, before you run into problems with any hard coded limit of MySQL itself.
The OS and the hardware will impose some (rather generous) restrictions. Memory, filesystem space, number of open table file limits, number of subdirectory limits, etc. MySQL might start to suffer from some performance problems if you add tens of thousands of entries to the information schema tables - hard to say for sure. Maybe a developer can chime in with more specifics about theoretical limits, or someone with practical exprience using LOTS of databases. My own installations have never had more than about 40 separate databases, which has obviously never approached any limit! Dan On 10/18/06, John M. Brown <[EMAIL PROTECTED]> wrote:
Thanks for the info, but my question is how many databases, not so much how many rows per table or how big the database can be... I mean, how many "create database ABC<insert # here>" can I do before MySQL says "sorry, you can't have more than X databases". Say I create 1000 empty MySQL databases (meaning no tables, just the schema)... would that work? what about 5000? ... make sense? On Wed, 18 Oct 2006 14:45:18 +0100, Philip Mather <[EMAIL PROTECTED]> wrote: > John, >> How many databases does a single instance of MySQL Server 5.x support? >> > I suspect you'll get a bit of a <shrug />, with a 64bit machine there's > a limit of 4.2 billion rows per table and with an XFS file system 8EB > per table, there's a join limit specified somewhere but I don't think > there's an explicit limit coded in anywhere? Assuming you have no other > hardware constraints beyond a 64bit processor (and that's an enormous > assumption) I'd imagine you'd explode one of the tables in the > information_schema database maybe. > > Having said all that I suspect that the effort to build a 128bit > processor with working generic *n!x kernel, ANSI C compiler and file > system (minus any 64bit constraints) would dwarf the work then needed to > compile MySQL onto it. > > So for the time being I'd suggest that it's safe to assume you'll find > your hardware's limits first. > > Regards, > Phil -- MySQL General Mailing List For list archives: http://lists.mysql.com/mysql To unsubscribe: http://lists.mysql.com/[EMAIL PROTECTED]
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