Re: 9.0beta2 - server crash when using HS + SR

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Robert Haas wrote:
> On Fri, Jun 11, 2010 at 9:29 PM, Rafael Martinez

> I'm somewhat disinclined to try to address this for 9.0. We've had
> this problem for a long time, and I'm not sure that the fact that it
> can now happen in a slightly wider set of circumstances is enough
> reason to engineer a solution so close to release time, nor am I sure
> what that other solution would look like. But I'm open to other
> opinions.
>

A minimum and probably the only feasible thing for 9.0 will be to update
the documentation. We need an entry in the hot-standby caveats section
explaining that if you create a tablespace and the directory needed does
not exist in the the standby, the standby will shutdown itself and will
not be able to start until the directory is also created in the standby.

For a DBA point of view, two possible solutions could be:

1) PostgreSQL creates the directory needed for the tablespace if the
user running postgres has privileges to do so at the OS level.

2) The standby discovers that the directory needed does not exist and
pauses the recovering (without shutting down the server) in the WAL
record that creates the tablespace. The standby will check periodically
if the directory is created before starting the recovery process again.

With this the users will be able to continue using and running queries
in the standby node. In very busy systems with many changes, the standby
will fall behind quite a lot if the error is not discovered and fixed
quickly. But in many other systems the delay will not be a problem as
serious as the loss of access to the standby.

regards,
- --
Rafael Martinez, <r(dot)m(dot)guerrero(at)usit(dot)uio(dot)no>
Center for Information Technology Services
University of Oslo, Norway

PGP Public Key: http://folk.uio.no/rafael/
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