Re: Concurrent table access from InnoDB
"Shawn Green (MySQL)" <[email protected]>
| Newsgroups | gmane.comp.db.mysql.devel |
|---|---|
| Organization | Oracle Corporation |
| Message-ID | <[email protected]> |
On 11/18/2011 16:29, Rick James wrote: > Is this what keeps there from being parallelism in PARTITIONed tables? > >... No. Those partitions are accessed internally. Multiple threads can be spawned in the context of resolving a single query. Any lack of parallelism in resolving PARTITIONed table queries is simply a matter of design time and effort. Now, in the context of accessing internal resources any query that requires a JOIN will need to touch at least two tables under the same user context. Perhaps I misunderstood the original question? > > Hi, > Is it possible for a client connection thread to access 2 tables concurrently from InnoDB, say using a slave thread ? Or is access limited to one table at a time per client connection thread ? Perhaps he was asking about the optimizer processing a command that needed to touch two or more tables? If that's the purpose of the question then of course more than one table can be accessed in the context of a single connection. This happens very frequently. I cannot say with absolute certainty if those tables are processed in parallel but I would be concerned if they were not. I was reading his question more like this: Can the same connection be used to open multiple queries where each query is pointing to a separate table? In that context, each connection can only have one active command. -- Shawn Green MySQL Principal Technical Support Engineer Oracle USA, Inc. - Hardware and Software, Engineered to Work Together. Office: Blountville, TN -- MySQL Internals Mailing List For list archives: http://lists.mysql.com/internals To unsubscribe: http://lists.mysql.com/[email protected]