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Testing hot standby on same server sharing same tablespace directory 3+ messages / 2 participants [nested] [flat]
* Testing hot standby on same server sharing same tablespace directory @ 2016-04-27 23:45 Sreekanth Palluru <Sreekanth.Palluru@superchoice.com.au> 0 siblings, 1 reply; 3+ messages in thread From: Sreekanth Palluru @ 2016-04-27 23:45 UTC (permalink / raw) To: pgsql-admin Hi I am testing hot standby on same server (version 9.5.2) , everything works well. I have a doubt regarding sharing of tablespace directory by these two databases . I have created a tablespace and moved few objects and I happen to see that same directory was being used by standby node aka slave node and to my surprise it still works without any issues. Is this expected ? I was expecting some sort of warnings from Postgres or am I missing something Master $PGDATA [pg952@pdb-poc01 pg_tblspc]$ pwd /opt/v9.5.2/data/pg_tblspc [pg952@pdb-poc01 pg_tblspc]$ ls -ltr total 0 lrwxrwxrwx. 1 pg952 dba 17 Apr 27 16:10 16495 -> /opt/v9.5.2/tbsp1 [pg952@pdb-poc01 pg_tblspc]$ I can access the tables [pg952@pdb-poc01 pg_tblspc]$ psql -d abcd -p 5432 psql (9.5.2) Type "help" for help. ssint=# select count(*) from t_random; count --------- 8000000 (1 row) ssint=# Standby/Slave $PGDATA [pg952@pdb-poc01 pg_tblspc]$ pwd /home/postgres95/data/pg_tblspc [pg952@pdb-poc01 pg_tblspc]$ ls -ltr total 0 lrwxrwxrwx. 1 pg952 dba 17 Apr 27 16:10 16495 -> /opt/v9.5.2/tbsp1 [pg952@pdb-poc01 pg_tblspc]$ [pg952@pdb-poc01 16412]$ psql -d abcd -p 54321 psql (9.5.2) Type "help" for help. ssint=# delete from t_random; ERROR: cannot execute DELETE in a read-only transaction ssint=# select count(*) from t_random; count --------- 8000000 (1 row) ssint=# -Sreekanth ^ permalink raw reply [nested|flat] 3+ messages in thread
* Re: Testing hot standby on same server sharing same tablespace directory @ 2016-04-28 01:55 Ian Barwick <ian@2ndquadrant.com> parent: Sreekanth Palluru <Sreekanth.Palluru@superchoice.com.au> 0 siblings, 1 reply; 3+ messages in thread From: Ian Barwick @ 2016-04-28 01:55 UTC (permalink / raw) To: Sreekanth Palluru <Sreekanth.Palluru@superchoice.com.au>; pgsql-admin On 04/28/2016 08:45 AM, Sreekanth Palluru wrote: > > Hi > > I am testing hot standby on same server (version 9.5.2) , everything works well. > I have a doubt regarding sharing of tablespace directory by these two databases . > > I have created a tablespace and moved few objects and I happen to see that same > directory was being used by standby node aka slave node and to my surprise it still works > without any issues. > > Is this expected ? Both instances will start and initially appear to function, but you are guaranteed to run into unexpected behaviour and some kind of corruption. Try e.g. creating and populating a table, then pausing replay on the standby; then drop and recreate/repopulate the same table. > I was expecting some sort of warnings from Postgres or am I missing something No, there's nothing which could warn about this particular scenario. Regards Ian Barwick -- Ian Barwick http://www.2ndQuadrant.com/ PostgreSQL Development, 24x7 Support, Training & Services -- Sent via pgsql-admin mailing list (pgsql-admin@postgresql.org) To make changes to your subscription: http://www.postgresql.org/mailpref/pgsql-admin ^ permalink raw reply [nested|flat] 3+ messages in thread
* Re: Testing hot standby on same server sharing same tablespace directory @ 2016-04-28 04:57 Sreekanth Palluru <Sreekanth.Palluru@superchoice.com.au> parent: Ian Barwick <ian@2ndquadrant.com> 0 siblings, 0 replies; 3+ messages in thread From: Sreekanth Palluru @ 2016-04-28 04:57 UTC (permalink / raw) To: Ian Barwick <ian@2ndquadrant.com>; pgsql-admin Thanks Ian -----Original Message----- From: Ian Barwick [mailto:ian@2ndquadrant.com] Sent: Thursday, 28 April 2016 11:55 AM To: Sreekanth Palluru <Sreekanth.Palluru@superchoice.com.au>; pgsql-admin@postgresql.org Subject: Re: [ADMIN] Testing hot standby on same server sharing same tablespace directory On 04/28/2016 08:45 AM, Sreekanth Palluru wrote: > > Hi > > I am testing hot standby on same server (version 9.5.2) , everything works well. > I have a doubt regarding sharing of tablespace directory by these two databases . > > I have created a tablespace and moved few objects and I happen to see > that same directory was being used by standby node aka slave node and > to my surprise it still works without any issues. > > Is this expected ? Both instances will start and initially appear to function, but you are guaranteed to run into unexpected behaviour and some kind of corruption. Try e.g. creating and populating a table, then pausing replay on the standby; then drop and recreate/repopulate the same table. > I was expecting some sort of warnings from Postgres or am I missing > something No, there's nothing which could warn about this particular scenario. Regards Ian Barwick -- Ian Barwick http://www.2ndQuadrant.com/ PostgreSQL Development, 24x7 Support, Training & Services -- Sent via pgsql-admin mailing list (pgsql-admin@postgresql.org) To make changes to your subscription: http://www.postgresql.org/mailpref/pgsql-admin ^ permalink raw reply [nested|flat] 3+ messages in thread
end of thread, other threads:[~2016-04-28 04:57 UTC | newest] Thread overview: 3+ messages (download: mbox mbox.gz follow: Atom feed) -- links below jump to the message on this page -- 2016-04-27 23:45 Testing hot standby on same server sharing same tablespace directory Sreekanth Palluru <Sreekanth.Palluru@superchoice.com.au> 2016-04-28 01:55 ` Ian Barwick <ian@2ndquadrant.com> 2016-04-28 04:57 ` Sreekanth Palluru <Sreekanth.Palluru@superchoice.com.au>
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