Re: Concurrent table access from InnoDB
Rick James <[email protected]>
| Newsgroups | gmane.comp.db.mysql.devel |
|---|---|
| Message-ID | <[email protected]> |
PARTITION has very few use cases where it performs better than a single table. This feels like a way to make PARTITION worth having. Oh, well, I keep hoping. Meanwhile, when someone says they will use PARTITION. I say "Why?". On 11/21/11 4:52 PM, Stewart Smith wrote: > On Mon, 21 Nov 2011 09:55:15 +0000, Mark Leith<[email protected]> wrote: >> This doesn't necessarily relate to the limitation of partitioned >> tables not having a multi-threaded read of partitions under the >> covers, as at the handler / SQL layer, MySQL is just waiting for the >> storage engine to return rows to it at the current step of JOIN >> execution - under the covers the storage engine could choose to access >> the partitions of a single table concurrently if it wanted to (we just >> don't have that in MySQL at the moment). > NDB does this. Multiple data nodes may be sending data back to the MySQL > server at once. > > This is a pretty limited form of parallelism though. > > Basically, concurrent query execution is hard and for the vast majority > of queries that MySQL processes, wouldn't see any or much improvement - > avoiding the added complexity (and performance impact for non > parallelized queries) of locking is a pretty big benefit. > > -- Rick James - MySQL Geek -- MySQL Internals Mailing List For list archives: http://lists.mysql.com/internals To unsubscribe: http://lists.mysql.com/[email protected]