Bug #61701 Multithread ALTER for partitioned InnoBD tables
Submitted: 29 Jun 2011 18:51 Modified: 30 Jun 2011 4:06
Reporter: Chris Wagner Email Updates:
Status: Verified Impact on me:
None 
Category:MySQL Server: InnoDB storage engine Severity:S4 (Feature request)
Version:5.5 OS:Any
Assigned to: CPU Architecture:Any
Tags: innodb multithreaded thread alter partitioned table

[29 Jun 2011 18:51] Chris Wagner 
Description:
One of the biggest time consumers with altering a large partitioned table is just the time MySQL needs to copy the data to the new temp table.  This pegs only 1 CPU core at 100% and barely touches the I/O capacity on the box.  It would be really nice if this process could be multithreaded to better utilize the capacity of modern dedicated database servers.

We have multigigabyte tables subpartitioned 1024 ways and it took almost an hour to alter.

Thanks.

How to repeat:
n/a

Suggested fix:
Add ALTER TABLE clause or some system variable to tell MySQL/InnoDB how many threads to use to accomplish the task.  Or infer number of threads from other settings, e.g. I/O capacity.
[30 Jun 2011 4:06] Valeriy Kravchuk 
Thank you for the feature request.