"lio bod" <liobod.slony at gmail.com> writes:
> Hello world,
>
>  
>
> May i have more info about 'slony1_extract_schema.sh ' command.
>
> I'm not sure to understand what it it it supposed to do.
>
>  
>
> For instance, looking at the doc (http://slony.info/documentation/adminscripts.html 19.4. slony1_extract_schema.sh) :
>
>  
>
>    o "It dumps the origin node's schema, including the data in the Slony-I cluster schema."
>      What is called 'origin node's schema' : My schema database before intrusive slony hacks?
>    o "A slonik script is run to perform UNINSTALL NODE on the temporary database. This eliminates all the special Slony-I tables, schema, and removes Slony-I triggers
>      from replicated tables."
>      At this step, does it mean i got my schema and data before any intrusive slony hacks?
>    o " Finally, pg_dump is run against the temporary database, delivering a copy of the cleaned up schema to standard output"
>      
>
>
>
> I expected a dumped file or new 'mytmpbase' in postgres.
> I understand this a design choice.
> Why not making a real dump on disk?
> Why removing the mytmpbase after the treatment?

It's working "the UNIX way;"

  - By delivering output to STDOUT, *you* get to choose what you do with
    the output

  - It removes the temporary database in order to attempt to be an
    idempotent operation, so that you could run this a second time
    without needing some special cleanup procedure.


> Btw i would like to submit here a weird test : i perform the command
> wheras the 'mytmpbase' already exits with a user is connected :

That obviously won't work, as creation of the database will fail, and
we really can't predict what that user might do, while connected.

That will injure the process, so don't do it.

>    o Btw, it always says at the begining of its process :
>      Warning: Set 1 does not origin on node 1 - original triggers and constraints will not be included in the dump
>      What are the potential impacts on my dump and on my 'mytmpbase'?
>      Is that in contradiction with the sentence 'delivering copy of the cleaned up schema' ?

It is warning you that it can't keep the promise it wanted to keep.

If you run it against a non-origin node, you will not get a totally
"cleaned up" schema.

>    o
>      
>
>    o At the end of this treatment:
>      
>      dropdb: échec de la suppression de la base de données: ERREUR:  La base de données « mytmpbase» est actuellement accédée par d'autres utilisateurs
>      As my terminal are still french go on approximatively translating :
>      dropdb: error on deleting database : ERROR: database  « mytmpbase» is beeing accessed by other users
>      
>      Indeed, 'mytmpbase' is not removed. May i trust it just like the dump into standard output? Will the restore of the dump be an image of 'mytmpbase'?
>
> Forgive me if this too dense, but i think any piece of answer will be usful not only for me but for the whole community,

Apparently you ran it on other than the origin node, so the result
will be a broken schema.

Evidently I need to add a warning to the documentation to indicate
that you shouldn't run this against a slave.  Done...

<http://lists.slony.info/pipermail/slony1-commit/2008-March/002213.html>
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