Re: how do I do dump and restore without bugging with constraint?

If you are going to modify the data structure then you will not be able
to apply pg_restore since data dump will be looking for a compatible
structure.
If you change a varchar to text or a integer to numeric, you will not
have any problems. But if you add extra columns, for example, data
import will fail.

So, if you are planning to perform and in-depth modification of your
data structure, do it in your server before export, or at least perform
those changes that modify data structure of your schema.

-----Original Message-----
From: Net Tree Inc. <nettreeinc(at)gmail(dot)com>
To: Iñigo Martinez Lasala <imartinez(at)vectorsf(dot)com>
Cc: pgsql-admin(at)postgresql(dot)org, pgsql-general(at)postgresql(dot)org
Subject: Re: [ADMIN] how do I do dump and restore without bugging with
constraint?
Date: Wed, 24 Feb 2010 09:56:35 +0800

Quote: "However if you have to modify table definitions, you will
probably not be able to import data in that new schema and it will be
necesary to look for a new strategy."

For schema, are we talking about attribute columns (structure of
table) and "table definitions" referraled you talking about
things like "data types"?
If error came out during restore are related with table definitions then
it's probably no help?

I see something related with Deferrable and Initially deferrable that
seems like something could avoid constraints when dumping and restore,
but it has to modify the table or re-create all of them to have such
option (maybe is what you referraled "table definitions"). Is it what it
can be use for to avoid during dumping and restoring?

DEFERRABLE
NOT DEFERRABLE

This controls whether the constraint can be deferred. A
constraint that is not deferrable will be checked immediately
after every command. Checking of constraints that are deferrable
can be postponed until the end of the transaction (using the SET
CONSTRAINTS command). NOT DEFERRABLE is the default. Only
foreign key constraints currently accept this clause. All other
constraint types are not deferrable.

INITIALLY IMMEDIATE
INITIALLY DEFERRED

If a constraint is deferrable, this clause specifies the default
time to check the constraint. If the constraint is INITIALLY
IMMEDIATE, it is checked after each statement. This is the
default. If the constraint is INITIALLY DEFERRED, it is checked
only at the end of the transaction. The constraint check time
can be altered with the SET CONSTRAINTS command.

On Wed, Feb 24, 2010 at 1:49 AM, Iñigo Martinez Lasala
<imartinez(at)vectorsf(dot)com> wrote:
To avoid contraints you have to use –disable-triggers flag
during restore. That is done in step 5.



In order to modify schema you have to locate what is failing.
So, first restore old schema without modifications in your new
database, watch for errors and fix them.

For example:

psql -U username -d database -h server_destination -f schema.sql
2>import_error.log



You’ll find all import errors in import_error.log. Since you are
only going to launch an schema definition, It will only take a
few seconds, so test all you need.

After locating errors, open schema.sql with your favorite editor
and fix them. There are minor changes between postgresql
versions and you’ll probably have no problems in order to fix
them, or ask here if you have many problems.

Once fixed, you will have your new modified_schema.sql and you
can proceed with steps 4 and 5.



Obviously, if errors are related to indexes, functions, broken
dependencies, etc without touching table definitions, everything
will go well. However if you have to modify table definitions,
you will probably not be able to import data in that new schema
and it will be necesary to look for a new strategy.




De: Net Tree Inc. [mailto:nettreeinc(at)gmail(dot)com]
Enviado el: martes, 23 de febrero de 2010 17:36
Para: Iñigo Martinez Lasala
CC: pgsql-admin(at)postgresql(dot)org; pgsql-general(at)postgresql(dot)org
Asunto: Re: [ADMIN] how do I do dump and restore without bugging
with constraint?





Thanks. Is it by doing these steps I can avoid constrain
restriction? for step 3, how should I modify the schema? and
which schema? the target DB's schema that I am trying to dump
the schema and data in? But this is the problem, I am not sure
whats different between the two schema's, there are just too
many tables to check. What's your tips?

Steven


On Tue, Feb 23, 2010 at 7:03 PM, Iñigo Martinez Lasala
<imartinez(at)vectorsf(dot)com> wrote:


Using pg_dump from your new host (that is, newer version)

1- Dump schema.
pg_dump -h server_source -U username -s -Fp -f schema.sql
database

2- Dump data only.
pg_dump -h server_source -U username -a -Fc -f data.dmp database

3- Modify schema.

4- Restore schema in new host.
psql -U username -d database -h server_destination -f
modified_schema.sql

5- Restore data disabling triggers
pg_restore -h server_destination -U username -d database
--disable-triggers -a data.dmp





-----Original Message-----
From: Net Tree Inc. <nettreeinc(at)gmail(dot)com>
To: pgsql-admin(at)postgresql(dot)org, pgsql-general(at)postgresql(dot)org
Subject: [ADMIN] how do I do dump and restore without bugging
with constraint?
Date: Tue, 23 Feb 2010 12:50:27 +0800

Hi all,

I am dumping both schema and data from old database to new one.
The new database schema is somehow contain slightly different
schema then the old one. When I do restore it shown alot errors
related with constraints. How can I dump and to restore from old
to new without dealing with constraint and just forces data dump
to where it suppose to belong?















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Steven Huang

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Steven Huang