Thank you, Gordon for your reply. In your patch I see that you are setting the isolation_level to REPEATABLE_READ. We are trying to change the isolation level to READ_COMMITTED. I like to refer you to this performance article[1] that determines that READ_COMMITTED is usually better than REPEATABLE_READ.
In addition, maybe an additional reason for your slowness is that you do it when you get the connection - so you do an extra DB command that sets the isolation level. My patch is changing the default isolation level for all connections upfront. [1] https://www.percona.com/blog/2015/01/14/mysql-performance-implications-of-innodb-isolation-modes/ From: gord chung [mailto:g...@live.ca] Sent: Tuesday, December 08, 2015 2:50 PM To: openstack-dev@lists.openstack.org Subject: Re: [openstack-dev] [oslo.db][sqlalchemy][mistral] Configuring default transaction isolation level we had this in ceilometer events. you can see it here: https://github.com/openstack/ceilometer/commit/898cd3d036c4358aa16f7b3e2028365dc9829213 note, that patch is removing it because it slowed everything way down because of locking. if you can avoid it, avoid it. On 08/12/2015 7:28 AM, Renat Akhmerov wrote: Hi, Moshe, thanks a lot for bringing this up. I remember I tried to find a way to change isolation level per connection but also was unable to do that. An advice from oslo team would be very helpful. Renat Akhmerov @ Mirantis Inc. On 08 Dec 2015, at 13:41, ELISHA, Moshe (Moshe) <moshe.eli...@alcatel-lucent.com<mailto:moshe.eli...@alcatel-lucent.com>> wrote: Hi, We at Mistral want to move from the default transaction isolation level of REPEATABLE READ to READ COMMITTED as part of a bugfix[1]. I did not find a way to pass the isolation level to sqlachemy using oslo.db and the current solution is to use monkey-patching[2] that adds the "isolation_level" property. Is there currently a better way to set the default isolation level? If not - I will create a BP for it. Thanks. [1] https://review.openstack.org/#/c/253819 [2] https://review.openstack.org/#/c/253819/11/mistral/db/sqlalchemy/base.py __________________________________________________________________________ OpenStack Development Mailing List (not for usage questions) Unsubscribe: openstack-dev-requ...@lists.openstack.org<mailto:openstack-dev-requ...@lists.openstack.org>?subject:unsubscribe http://lists.openstack.org/cgi-bin/mailman/listinfo/openstack-dev __________________________________________________________________________ OpenStack Development Mailing List (not for usage questions) Unsubscribe: openstack-dev-requ...@lists.openstack.org?subject:unsubscribe<mailto:openstack-dev-requ...@lists.openstack.org?subject:unsubscribe> http://lists.openstack.org/cgi-bin/mailman/listinfo/openstack-dev -- gord
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