From: Howard Hart
Date: November 25 2008 8:36pm
Subject: Re: Mysql and Flashback
List-Archive: http://lists.mysql.com/mysql/215370
Message-Id: <492C61C6.7070000@ooma.com>
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slave lag should be easy to do with a simple bash script. i.e. -

desired_delay=3600  # one hour lag

while sleep 60
do
  behind=`mysql -u root --password=foobar -e "show slave status\G" | 
grep 'Seconds_Behind_Master:' | awk '{ printf "%s\n", $2 }'`
  if [ $behind < $desired_delay ]; then
      mysql -u root --password=foobar -e "slave stop"
      holdtime=`expr $desired_delay  -  $behind`
      if [ $holdtime -gt 0]; then
          mysql -u root --password=foobar -e "slave stop"
      fi
  else
      mysql -u root --password=foobar -e "slave start"
  fi
done


Not pretty, but should do the job with more sanity checks, with the 
caveat that sometimes Seconds_Behind_Master can return some interesting 
values....

Howard Hart
Ooma, Inc.

ewen fortune wrote:
> Hi Shain,
>
> If you are using InnoDB its possible to patch to allow this functionality.
>
> Percona are in the early stages of developing a patch specifically to
> allow flashback type access to previous table states.
>
> https://bugs.launchpad.net/percona-patches/+bug/301925
>
> If you wanted to go down the slave lag road, Maatkit has a tool for doing that.
>
> http://www.maatkit.org/doc/mk-slave-delay.html
>
> Cheers,
>
> Ewen
>
> On Tue, Nov 25, 2008 at 6:57 PM, Shain Miley <smiley@stripped> wrote:
>   
>> Hello,
>> We are planning on trying to do an Oracle to MySQL migration in the near
>> future.  The issue of a Mysql equivalent to Oracle's flashback was being
>> discussed.  After some digging  it appears that there is no such feature in
>> Mysql. One thought that I had was to do some intentional replication lag
>> (say 12 to 24 hours)...that way if we needed to revert back we would have
>> the option of doing so.
>>
>> Does anyone:
>>
>> a: know how to setup a replication to intentionally lag?
>>
>> b: know of a better way of engineering a flashback equivalent for Mysql?
>>
>> Thanks in advance,
>>
>> Shain
>>
>> --
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>>
>>
>>     
>
>