Re: [GENERAL] Copy database to another host without data fromspecific tables

On 07/03/2017 09:02, Panagiotis Atmatzidis wrote:
> Hello,
>
> I have 2 RDS instances on AWS running PSQL 9.4.7.
>
> I want to make a clone of database1 which belongs to user1, to database2 which belongs to user2. Database1 has 20+
tables.I want to avoid copying the DATA sitting on 5 tables on database1 (many Gigs). 
>
> I've read one too many posts about how to perform the actions with "pg_dump" and "pg_restore" but I'm trying to
figureout the easiest way to do this. The process I have in mind is this: 
>
> 1) pg_dump the schema from DB1 to DB2 using --no-owner and pg_restore with --role=user2
> 2) pg_dump -Fc --no-owner --data-only -t 'table1' from DB1 and then restore with pg_restore -t 'table' --role=user2
<table.sql>to DB2 
So you are talking about DBs on the same PgSQL cluster (RDS instance) or you are trying to clone a DB from 1st RDS
instanceto the 2nd? In each case, you cannot avoid copying. But if we're talking  
about the whole cluster ....
> This procedure though is very time consuming (although it could be scripted). Is there any better / faster / safer
wayto do this? 
you could design smth based on replication, have a warm/hot standby applying changes from the primary, and then
implementsmth like : 
- promote (i.e. recover and start in a new timeline as a new primary)
- run a script to change ownership to user2.
So the idea is to have pre-copied the data, so that the whole final procedure is very fast. Note, however, that after
youdo that, you would have to re-setup replication again, and that would be  
costly (you can't avoid ultimately copying data). Maybe it could help if you tell us the whole use case.

> Thanks.
>
> --
> Panagiotis (atmosx) Atmatzidis
>
> email:    atma@convalesco.org
> URL:    http://www.convalesco.org
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>
> "Everyone thinks of changing the world, but no one thinks of changing himself.” - Leo Tolstoy
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--
Achilleas Mantzios
IT DEV Lead
IT DEPT
Dynacom Tankers Mgmt