Postgresql – Data missing in PostgreSQL dump

A UNIQUE constraint is not a trigger. It is implemented by way of a unique index. So it cannot be turned off with --disable-triggers.

"Other objects" that depend on a the unique constraint are typically foreign key constraints. Those cannot exist without a unique (or primary key) constraint on the referenced column(s). To enable the restore, you could remove all such fk constraints together with the unique constraint.

Of course, to restore referential integrity, you would then have to eliminate violating duplicates and re-create all removed constraints. If you cannot afford to have an inconsistent state, even temporarily, do it all in a single (automatically blocking) transaction.

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If you cannot afford exclusive locks on involved tables, your only remaining option is to fix your data first. This is probably the best course of action either way. You could import your data to temporary tables with COPY, remove duplicates, and then INSERT into the target tables.

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If, on the other hand, you run into missing values for foreign keys, you can improvise with NOT VALID fk constraints:

• Disable all constraints and table checks while restoring a dump

Your problem should never occur to begin with. If you actually have a UNIQUE constraint in place, you cannot have duplicate values in your source database - unless it's seriously broken. If that's the case, fix your source db first ...

The error is harmless but to get rid of it, I think you need to break this restore into two commands, as in:

dropdb -U postgres mydb && \
 pg_restore --create --dbname=postgres --username=postgres pg_backup.dump

The --clean option in pg_restore doesn't look like much but actually raises non-trivial problems.

For versions up to 9.1

The combination of --create and --clean in pg_restore options used to be an error in older PG versions (up to 9.1). There is indeed some contradiction between (quoting the 9.1 manpage):

--clean Clean (drop) database objects before recreating them

and

--create Create the database before restoring into it.

Because what's the point of cleaning inside a brand-new database?

Starting from version 9.2

The combination is now accepted and the doc says this (quoting the 9.3 manpage):

--clean Clean (drop) database objects before recreating them. (This might generate some harmless error messages, if any objects were not present in the destination database.)

--create Create the database before restoring into it. If --clean is also specified, drop and recreate the target database before connecting to it.

Now having both together leads to this kind of sequence during your restore:

DROP DATABASE mydb;
...
CREATE DATABASE mydb WITH TEMPLATE = template0... [other options]
...
CREATE SCHEMA public;
...
CREATE TABLE...

There is no DROP for each individual object, only a DROP DATABASE at the beginning. If not using --create this would be the opposite.

Anyway this sequence raises the error of public schema already existing because creating mydb from template0 has imported it already (which is normal, it's the point of a template database).

I'm not sure why this case is not handled automatically by pg_restore. Maybe this would cause undesirable side-effects when an admin decides to customize template0 and/or change the purpose of public, even if we're not supposed to do that.