I think pg_rewind's feature to rewind the promoted standby as a new
standby is broken in 11
STEPS:
1. create master standby setup.
Use below script for same.
2. Promote the standby
[mithuncy@localhost pgrewmasterbin]$ ./bin/pg_ctl -D standby promote
waiting for server to promote.... done
server promoted
3. In promoted standby create a database and a table in the new database.
[mithuncy@localhost pgrewmasterbin]$ ./bin/psql -p 5433 postgres
postgres=# create database db1;
CREATE DATABASE
postgres=# \c db1
You are now connected to database "db1" as user "mithuncy".
db1=# create table t1 (t int);
CREATE TABLE
4. try to rewind the newly promoted standby (with old master as source)
[mithuncy@localhost pgrewmasterbin]$ ./bin/pg_ctl -D standby stop
waiting for server to shut down....... done
server stopped
[mithuncy@localhost pgrewmasterbin]$ ./bin/pg_rewind -D standby
--source-server="host=127.0.0.1 port=5432 user=mithuncy
dbname=postgres"
servers diverged at WAL location 0/3000060 on timeline 1
rewinding from last common checkpoint at 0/2000060 on timeline 1
could not remove directory "standby/base/16384": Directory not empty
Failure, exiting
Note: dry run was successful!
[mithuncy@localhost pgrewmasterbin]$ ./bin/pg_rewind -D standby
--source-server="host=127.0.0.1 port=5432 user=mithuncy
dbname=postgres" -n
servers diverged at WAL location 0/3000060 on timeline 1
rewinding from last common checkpoint at 0/2000060 on timeline 1
Done!
Also I have tested same in version 10 it works fine there.
Did below commit has broken this feature? (Thanks to kuntal for
identifying same)
commit 266b6acb312fc440c1c1a2036aa9da94916beac6
Author: Fujii Masao <fujii@postgresql.org>
Date: Thu Mar 29 04:56:52 2018 +0900
Make pg_rewind skip files and directories that are removed during server start.
--
Thanks and Regards
Mithun Chicklore Yogendra
EnterpriseDB: http://www.enterprisedb.com
