Re: Cascade streaming replication + wal_files - Pgsql 9.2

On Thu, 7 Jul 2016, 10:32 a.m. Patrick B, <patrickbakerbr(at)gmail(dot)com> wrote:

> The slave02 server will be a copy of the DB into Amazon. There will be a
> migration to Amazon in the future, and the company's managers want a copy
> of the current DB there to test and do all the stuffs they need (migrating
> to 9.5, too).
>

Have you checked out Amazon's DMS?

> slave01 is already working as a streaming replication server.
> The master server sends the wal_files to slave01 by archive_command.
>
> The plan below isn't my idea, I would do different but isn't my call:
>

Been there :)

>
> *Current scenario:*
>
> master stores wal_files into slave01
> slave02 does not exists
>
>
> *The plan is:*
>
> 1. setup slave02 at amazon EC2 (just for testing and future master server
> for devs)
>

Is it EC2 Classic? Or is it EC2 Virtual Pvt Cloud (VPC)?

> 2. setup postgres on slave02 (9.2)
> 3. pg_basebackup will be run from slave01. This will split the base in
> files of 50GB each (example)
> 4. Send the splitted files from slave01 to slave02
> 5. restore/join the files
> 6. start postgres on the slave02 slave
> 7. restore the DB using the wal_files from slave01
>

Given that slave02 is a standby, how do you plan on doing your regression
testing? It will be just a read only database.

You can restore the wal_file by specifying resotre_command to copy from the
archive generated by the master (rsync or scp to pull from your in-premise
setup to EC2). This would be fairly simple if you are using VPC

Question:
>
> Is possible to make slave01 archive the wal_files?
>

If you really can not just live with archive generated on master itself,
you need to try the options discussed up thread.
1. Copy the archives generated on master to a shared location or may be
copy it to S3 bucket
2. Archive generated on master is rsync (schedule basis) to EC2
3. pg_receivexlog running on EC2 to copy WAL from slave01

can just be a archive_command and archive_mode = on?
>

Setting these parameters on slave02 will have not any effect.

> --
--
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Sameer Kumar | DB Solution Architect
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