← Back to team overview

maria-discuss team mailing list archive

Re: [EXTERNAL] Re: Copying database files


Am 13.08.2018 um 14:33 schrieb Sergei Golubchik:
> On Aug 13, Reindl Harald wrote:
>> Am 13.08.2018 um 12:22 schrieb Ling, Andy:
>>>> "The advantage of FLUSH TABLES table_name FOR EXPORT is that the table
>>>> is read locked until UNLOCK TABLES is executed" is not really true
>>>> because that's only valid for the running connection
>>> Surely not. If you've locked a table for read only nothing should be
>>> able to write to it from any connection otherwise what's the point
>>> of a multi-threaded server? Tests suggest otherwise.
>> surely YES
>> https://blogs.vmware.com/vsphere/2014/12/mysql-backup-with-vdp.html
>> "Another item to be aware of with this statement is that the read lock
>> is released as soon as the session that made the call ends. When the
>> pre-freeze-script finishes, the session is closed" - try it out
>> and how do you make a script that locks the table and continues without
>> closing the session to mysqld?
> It's possible. In one of my personal projects I've used something like
> echo "flush tables with read lock;\n\! mysqlhotcopy ..." | mysql

please read again what i quoted from the article!
it is *not* possible except for some very limited usecases

* vmware calls a shell script which should lock tables
* vmware does fs-freeze, the script is completly finished
* vmware takes a snaphot of the guest
* from the moment the script with "flush tables with read lock;"
  has finsihed the lock is gone