On Sat, 11 Dec 1999, Oleg Bartunov wrote:

> I have a problem with pg_dump (6.5.3) if I use
> create table  foo (
>            a text  default foo_function()
>                   );
> where foo_function() is my function.
> pg_dump dumps create table first and create function
> later. Obvioulsy restoring doesn't works and
> I have to edit dump file. It's rather annoying.
> Is it fixed in current tree ?

What though if a function accesses a table? Which one goes first? Do we
have to maintain a network of dependencies in pg_dump? Eventually we'll
probably have to, with all the foreign key stuff coming up. Gloomy
prospects.

	-Peter

-- 
Peter Eisentraut                  Sernanders vaeg 10:115
peter_e@gmx.net                   75262 Uppsala
http://yi.org/peter-e/            Sweden


Sat, 11 Dec 1999 13:47:31 +0100 (MET)
Peter Eisentraut <e99re41@DoCS.UU.SE>
Re: [PATCHES] pg_dump primary keys
Peter Eisentraut wrote:

> What though if a function accesses a table? Which one goes first? Do we
> have to maintain a network of dependencies in pg_dump? Eventually we'll
> probably have to, with all the foreign key stuff coming up. Gloomy
> prospects.

    No  need  to  worry  about  FOREIGN  KEY  stuff  here.  These
    functions are generic builtins not dumped at all.

    But need to worry about all other functions of all languages.
    They  can be used in a table schema and OTOH their definition
    might need a relation to exist  (could  have  tuple  type  as
    argument).   Plus,  for SQL language functions (only SQL, not
    PL/pgSQL or any other language)  their  body  is  checked  at
    CREATE time for syntax, so relations they use are required.

    This can only be solved by your mentioned dependency network.

    BTW: All this was one reason to dump views  as  CREATE  TABLE
    and   later   CREATE   RULE.  Because  views  likely  contain
    functions.


Jan

--

#======================================================================#
# It's easier to get forgiveness for being wrong than for being right. #
# Let's break this rule - forgive me.                                  #
#========================================= wieck@debis.com (Jan Wieck) #




Sat, 11 Dec 1999 14:28:19 +0100 (MET)
wieck@debis.com (Jan Wieck)
Re: [HACKERS] Re: [PATCHES] pg_dump primary keys
Peter Eisentraut wrote:
>> What though if a function accesses a table? Which one goes first? Do we
>> have to maintain a network of dependencies in pg_dump? Eventually we'll
>> probably have to, with all the foreign key stuff coming up. Gloomy
>> prospects.

Couldn't we solve this by the simple expedient of dumping all the
objects in the database in OID order?

Expecting pg_dump to parse function bodies to discover what
relations/types are mentioned doesn't look appetizing at all...

			regards, tom lane

Sat, 11 Dec 1999 12:58:44 -0500
Tom Lane <tgl@sss.pgh.pa.us>
Re: [HACKERS] Re: [PATCHES] pg_dump primary keys 
On 1999-12-11, Tom Lane mentioned:

> Peter Eisentraut wrote:
> >> What though if a function accesses a table? Which one goes first? Do we
> >> have to maintain a network of dependencies in pg_dump? Eventually we'll
> >> probably have to, with all the foreign key stuff coming up. Gloomy
> >> prospects.
> 
> Couldn't we solve this by the simple expedient of dumping all the
> objects in the database in OID order?

Wow, great idea! That might actually solve all (well, most) pg_dump
related problems once and for all. Of course how you get all objects in
the database in oid order is to be determined.

-- 
Peter Eisentraut                  Sernanders vï¿½g 10:115
peter_e@gmx.net                   75262 Uppsala
http://yi.org/peter-e/            Sweden



Sun, 12 Dec 1999 03:06:49 +0100 (CET)
Peter Eisentraut <peter_e@gmx.net>
Re: [HACKERS] Re: [PATCHES] pg_dump primary keys 
Peter Eisentraut <peter_e@gmx.net> writes:
>> Couldn't we solve this by the simple expedient of dumping all the
>> objects in the database in OID order?

> Wow, great idea! That might actually solve all (well, most) pg_dump
> related problems once and for all. Of course how you get all objects in
> the database in oid order is to be determined.

I think it would take some restructuring in pg_dump: instead of
processing each type of database object separately, it would have to
grab some info (at least the OIDs and types) for all the different
objects in the DB, then sort this info by OID, and finally get the
details and produce the output for each object in OID order.

This would still fail in some pathological cases involving ALTER --- for
example, make a table, later create a new datatype, and then ALTER TABLE
ADD COLUMN of that datatype.  So the next refinement would be to examine
dependencies and do a topological sort rather than a simple sort by OID.
We'd still have to restructure pg_dump as above, though, and "examining
dependencies" is not exactly trivial for function bodies in unknown PL
languages...

If we had ALTER FUNCTION, which we don't but should, I think it would
actually be possible to create circular dependencies for which there is
*no* dump order that will work :-(.  So I'm not sure it's worth the
trouble to add dependency extraction and a topological sort algorithm
to pg_dump rather than just sorting by OID.  Dumping in OID order will
solve 99% of the problem with a fraction of the work.

			regards, tom lane

Sun, 12 Dec 1999 01:52:41 -0500
Tom Lane <tgl@sss.pgh.pa.us>
Re: [HACKERS] Re: [PATCHES] pg_dump primary keys 
Added to TODO list.

> Peter Eisentraut wrote:
> >> What though if a function accesses a table? Which one goes first? Do we
> >> have to maintain a network of dependencies in pg_dump? Eventually we'll
> >> probably have to, with all the foreign key stuff coming up. Gloomy
> >> prospects.
> 
> Couldn't we solve this by the simple expedient of dumping all the
> objects in the database in OID order?
> 
> Expecting pg_dump to parse function bodies to discover what
> relations/types are mentioned doesn't look appetizing at all...
> 
> 			regards, tom lane
> 
> ************
> 


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  pgman@candle.pha.pa.us               |  (610) 853-3000
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Thu, 1 Jun 2000 13:57:34 -0400 (EDT)
Bruce Momjian <pgman@candle.pha.pa.us>
Re: Re: [PATCHES] pg_dump primary keys