Re: tablespaces inside $PGDATA considered harmful

On 01/30/2015 08:19 AM, Bruce Momjian wrote:
>
> On Fri, Jan 30, 2015 at 11:12:43AM -0500, Robert Haas wrote:
>> I think everyone who has read this mailing list for a while is
>> probably already aware of this problem. When you create a tablespace
>> somewhere inside the data directory, weird things happen. If you
>> pg_upgrade and then incautiously run the delete_old_cluster.sh script
>> thus created, you will blow away large chunks of your data.[1] If you
>
> pg_upgrade doesn't create the deletion script in this case, and warns
> the user:
>
> Could not create a script to delete the old cluster's data
> files because user-defined tablespaces exist in the old cluster
> directory. The old cluster's contents must be deleted manually.
>
>> In the short term, I favor just adding a warning, so that people get
>> some clue that they are doing something that might be a bad idea. In
>> the long term, we might want to do more. Thoughts?
>
> Yes, good idea.

Uhm, wouldn't it be a rather simple patch to say:

if tablespace_create() in $PGDATA:
ERROR!

?

I mean yes a warning is good but it is after the fact, the tablespace is
already created. We know that tablespaces in $PGDATA are a bad idea, why
not protect the user?

JD

>

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