Bug #76960 InnoDB updates SYS_TABLESPACES, SYS_DATAFILES on every startup
Submitted: 6 May 2015 22:17 Modified: 19 May 2015 19:44
Reporter: Kevin Lewis Email Updates:
Status: Closed Impact on me:
None 
Category:MySQL Server: InnoDB storage engine Severity:S3 (Non-critical)
Version:5.7.6 OS:Any
Assigned to: CPU Architecture:Any

[6 May 2015 22:17] Kevin Lewis 
Description:
At startup, InnoDB is updating the system table SYS_DATAFILES with the space_id and path of each system tablespace file (./ibdata1, etc).  This is unnecessary and problematic since REDO and UNDO records are always created early in the bootup process.  

How to repeat:
Set a break on Datafile::replace_in_dictionary and start InnoDB.

Suggested fix:
If the correct records are found in SYS_DATAFILES, they need not be written.
[19 May 2015 19:44] Daniel Price 
Posted by developer:
 
Fixed as of the upcoming 5.7.8, 5.8.0 releases, and here's the changelog entry:

At startup, "InnoDB" updated the "SYS_DATAFILES" internal system table
with the "space_id" and path of each system tablespace file even though a
record was already present and "SYS_DATAFILES.PATH" matched the current
value.