Thanks for the feedback. Btw, pg_rewind is not a project included in Postgres core as a contrib module or anything, so could you send your feedback and the issues you find directly on github instead? The URL of the project is https://github.com/vmware/pg_rewind.
Sure, I will add those issues on github.
Either way, here are some comments below...
On Wed, Oct 23, 2013 at 6:07 PM, Samrat Revagade <revagade.samrat@gmail.com> wrote: > While testing pg_rewind I encountered following problem. > I used following process to do the testing, Please correct me if I am doing > it in wrong way. > > Problem-1: > pg_rewind gives error (target master must be shut down cleanly.) when > master crashed unexpectedly. > > 1. Setup Streaming Replication (stand alone machine : master server port > -5432, standby server port-5433 ) > 2. Do some operation on master server: > postgres=# create table test(id int); > 3. Crash the Postgres process of master: > kill -9 [pid of postgres process of master server] > 4. Promote standby server > 5. Run pg_rewind: > $ /samrat/postgresql/contrib/pg_rewind/pg_rewind -D > /samrat/master-data/ --source-server='host=localhost port=5433 > dbname=postgres' -v > connected to remote server > fetched file "global/pg_control", length 8192 > target master must be shut down cleanly. > 6. Check masters control information: > $ /samrat/postgresql/install/bin/pg_controldata > /samrat/master-data/ | grep "Database cluster state" > Database cluster state: in production > > IIUC It is because pg_rewind does some checks before resynchronizing the > PostgreSQL data directories. > But In real time scenarios, for example due to hardware failure if master > crashed and its controldata shows the state "in production" then pg_rewind > will fail to pass this check.
Yeah, you could call that a limitation of this module. When I looked at its code some time ago, I had on top of my mind the addition of an option of the type --force that could attempt resynchronization of a master even if it did not shut down correctly.
