Re: pg_depend explained - Mailing list pgsql-hackers

From Joel Jacobson
Subject Re: pg_depend explained
Date
Msg-id AANLkTimao2H55UZt0eiobkf8Dt3=Ng=iOnUZmfSesBEu@mail.gmail.com
Whole thread Raw
In response to Re: pg_depend explained  (Florian Pflug <fgp@phlo.org>)
Responses Re: pg_depend explained  (Florian Pflug <fgp@phlo.org>)
List pgsql-hackers
2011/1/11 Florian Pflug <fgp@phlo.org>:
> Could you give an example of the kind of trouble you're experiencing trying
> to use a topological sort?

Let's say you have a table t and a view v.
The view v is defined as select * from t;
If we put all objects in a tree, with the public schema as the root,
both v and t will directly under the root, but in reality, v cannot be
created before t.
This is the reason why a normal topological sort doesn't work.
You have to look at the deptype and sort nodes having "internal" edges
between them differently.
The pg_dump source code of course contains all the logic necessary to
do the trick, but it's not that easy to follow.

I guess it's time for plan B, sorting based on oid, no biggie, it will
work for my purpose, but it's damn ugly.

-- 
Best regards,

Joel Jacobson
Glue Finance


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