archive_command vs recovery_command paths

Started by Craig Ringerabout 12 years ago2 messagesdocs
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#1Craig Ringer
craig@2ndquadrant.com

Hi folks

Another point of confusion I've been seeing a lot in users on Stack
Overflow, dba.stackexchange.com, etc surrounds the meaning of paths
given in archive_command and restore_command.

Lots of people seem to assume that they are both relative to the master,
and that the master will run the restore_command to fetch archives to
send to the replica on request.

(Yes, I know that's completely missing the point of archive-based
replication, but it seems common).

So I think docs changes are needed to the explanations of those options,
and to the replication/recovery section, that better explain that we
assume there's shared storage like NFS involved, and if there isn't you
need to use commands like scp/rsync instead, or use tools like WAL-E.

I'm not going to get time to do this one for at least a few days, but
I'm posting it now partly so I don't forget about it.

--
Craig Ringer http://www.2ndQuadrant.com/
PostgreSQL Development, 24x7 Support, Training & Services

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#2Bruce Momjian
bruce@momjian.us
In reply to: Craig Ringer (#1)
Re: archive_command vs recovery_command paths

On Thu, Feb 13, 2014 at 08:20:02AM +0800, Craig Ringer wrote:

Hi folks

Another point of confusion I've been seeing a lot in users on Stack
Overflow, dba.stackexchange.com, etc surrounds the meaning of paths
given in archive_command and restore_command.

Lots of people seem to assume that they are both relative to the master,
and that the master will run the restore_command to fetch archives to
send to the replica on request.

(Yes, I know that's completely missing the point of archive-based
replication, but it seems common).

So I think docs changes are needed to the explanations of those options,
and to the replication/recovery section, that better explain that we
assume there's shared storage like NFS involved, and if there isn't you
need to use commands like scp/rsync instead, or use tools like WAL-E.

I'm not going to get time to do this one for at least a few days, but
I'm posting it now partly so I don't forget about it.

I have applied the attached patch which at least clarifies this issue.

--
Bruce Momjian <bruce@momjian.us> http://momjian.us
EnterpriseDB http://enterprisedb.com

+ Everyone has their own god. +

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