MySQL Bugs: #73875: Clarify documentation for INPLACE ALTER TABLEs etc

Bug #73875	Clarify documentation for INPLACE ALTER TABLEs etc
Submitted:	10 Sep 2014 13:46
Reporter:	Simon Mudd (OCA)	Email Updates:
Status:	Open	Impact on me:	None
Category:	MySQL Server: Documentation	Severity:	S4 (Feature request)
Version:	5.6	OS:	Any
Assigned to:		CPU Architecture:	Any

Description:
I was looking at this http://dev.mysql.com/doc/refman/5.6/en/innodb-create-index-overview.html and tried to add a comment but it suggested I make a feature request...

The comments "... the data is reorganized substantially, so it is still an expensive operation."

Perhaps the "reorganised substantially" actually means "it still takes a long time and you have to wait for it to completely finish".  I initially read this to mean "it happens immediately and the reorganisation happens in the background, but while that would be nice I'm guessing that is not the behaviour".

Please confirm and make the wording clearer.

How to repeat:
Read docs.
I find them rather vague.
Perhaps the time to rebuild the whole table is greater than building just a new index in the same tablespace, but I find the wording rather vague.

Suggested fix:
Documentation:

If possible please clarify the documentation.
Please clarify that these reorganisations are done synchronously and thus not in the background.

Behaviour:

Doing some of these changes in the background might be really nice. Yes, that's more complex but it would make our life much easier. If that were to be done, please ensure that this process can be throttled so that normal behaviour is not unduly affected and also that any background processing like this can be monitored easily.