Обсуждение: migration from 9.4 to 9.6

On 12/6/19 1:19 PM, Julie Nishimura wrote:
> Hello there, what would be my best way to migrate 2 tb single database 
> from cluster 9.4 to another machine on 9.6?

Not clear if you want to add database to an existing 9.6 cluster or 
create a new 9.6 cluster containing the 9.4 database?

> 
> Thank you!


-- 
Adrian Klaver
adrian.klaver@aklaver.com

On 12/6/19 1:38 PM, Julie Nishimura wrote:
> I'd like to copy one single database from 9.4 cluster to a new 9.6 
> cluster (migration with the upgrade), to the different host

Choices:

1) Dump/restore.

2) Afore mentioned Slony.

3) The pglogical 
extension(https://www.2ndquadrant.com/en/resources/pglogical/pglogical-docs/). 
The forerunner to the built in logical replication in 10+.

> 
> 
> ------------------------------------------------------------------------
> *From:* Adrian Klaver <adrian.klaver@aklaver.com>
> *Sent:* Friday, December 6, 2019 1:32 PM
> *To:* Julie Nishimura <juliezain@hotmail.com>; 
> pgsql-general@lists.postgresql.org <pgsql-general@lists.postgresql.org>; 
> pgsql-general <pgsql-general@postgresql.org>
> *Subject:* Re: migration from 9.4 to 9.6
> On 12/6/19 1:19 PM, Julie Nishimura wrote:
>> Hello there, what would be my best way to migrate 2 tb single database 
>> from cluster 9.4 to another machine on 9.6?
> 
> Not clear if you want to add database to an existing 9.6 cluster or
> create a new 9.6 cluster containing the 9.4 database?
> 
>> 
>> Thank you!
> 
> 
> -- 
> Adrian Klaver
> adrian.klaver@aklaver.com


-- 
Adrian Klaver
adrian.klaver@aklaver.com

I'd like to copy one single database from 9.4 cluster to a new 9.6 cluster (migration with the upgrade), to the different host

P {margin-top:0;margin-bottom:0;}

On Fri, 2019-12-06 at 21:38 +0000, Julie Nishimura wrote:

I'd like to copy one single database from 9.4 cluster to a new 9.6 cluster (migration with the upgrade), to the different host

Put 9.4 on the new server. Replicate the db to it. When you're ready to switch, shut down the master, promote the new db, and then shut it down and pg_upgrade -k it to 9.6.

That does require the binaries from both versions to be on the new server for a while, but it'll give you the least downtime and it's a very simple replication setup.

This is the plan we're going to follow to migrate from 9.2 to 9.6, as this is the only way to achieve almost zero downtime. The cons are, despite what Alan has mentioned, that you need double space because you have to create a slave replica.