Thread: BUG #9442: Cannot pg_dump database with event trigger: cannot duplicate null pointer.

The following bug has been logged on the website:

Bug reference:      9442
Logged by:          CHECICHES Marius-Cristian
Email address:      mcheciches@gmail.com
PostgreSQL version: 9.3.0
Operating system:   Oracle SunOS 5.11 Solaris 11.1
Description:

Note: I will try and not give away internal information as much as
possible.

The server is hosted on Solaris 11(operating system field). The pg_dump
utility was run remotely on Windows Server 2008 R2 Enterprise.

Command:    pg-9.3\pg_dump.exe -h <host> -p <port> -U <user> -F d -w -v -j 4
-f "<path>" <database>
This is run daily on a few small databases.
As soon as I implemented an event trigger it failed.

The trigger script:

=== trigger.sql
=========================================================================================

DROP EVENT TRIGGER IF EXISTS upd_perm_event_trigger;

CREATE EVENT TRIGGER upd_perm_event_trigger ON ddl_command_end
WHEN TAG IN ('CREATE TABLE', 'CREATE SEQUENCE', 'CREATE SCHEMA')
EXECUTE PROCEDURE upd_perm_trigger_fun(); --Set necessary permisions for new
relations

=========================================================================================================

I am aware of the ALTER DEFAULT PRIVILEGES feature, but I had my reasons to
prefer a trigger for this.
Anyway, the point is that pg_dump failed.

pg_dump logs (lines starting with '#' are comments added by me):

=== pg_dump.log ===============================================

pg_dump: reading schemas
pg_dump: reading user-defined tables
pg_dump: reading extensions
pg_dump: reading user-defined functions
pg_dump: reading user-defined types
pg_dump: reading procedural languages
pg_dump: reading user-defined aggregate functions
pg_dump: reading user-defined operators
pg_dump: reading user-defined operator classes
pg_dump: reading user-defined operator families
pg_dump: reading user-defined text search parsers
pg_dump: reading user-defined text search templates
pg_dump: reading user-defined text search dictionaries
pg_dump: reading user-defined text search configurations
pg_dump: reading user-defined foreign-data wrappers
pg_dump: reading user-defined foreign servers
pg_dump: reading default privileges
pg_dump: reading user-defined collations
pg_dump: reading user-defined conversions
pg_dump: reading type casts
pg_dump: reading table inheritance information
pg_dump: reading event triggers
pg_dump: finding extension members
pg_dump: finding inheritance relationships
pg_dump: reading column info for interesting tables
# START repeat for tables
pg_dump: finding the columns and types of table "<table>"
pg_dump: finding default expressions of table "<table>"
# END repeat
pg_dump: flagging inherited columns in subtables
pg_dump: reading indexes
# START repeat for tables
pg_dump: reading indexes for table "<table>"
# END repeat
pg_dump: reading constraints
pg_dump: reading triggers
pg_dump: reading rewrite rules
pg_dump: reading large objects
pg_dump: reading dependency data
pg_dump: saving encoding = UTF8
pg_dump: saving standard_conforming_strings = on
pg_dump: saving database definition
cannot duplicate null pointer (internal error)

================================================================

The logs were the same for each database. After I dropped the trigger and
re-run the
command it worked.
Note: I only dropped the trigger itself. The trigger function remained and
was dumped.

The new logs would end (normally) with:

====================================================
pg_dump: saving database definition
# START repeat for tables
pg_dump: dumping contents of table <table>
# END repeat
====================================================

I found no related information in the server-side log files.

mcheciches@gmail.com writes:
> pg_dump: saving database definition
> cannot duplicate null pointer (internal error)

I failed to reproduce this in 9.3 branch tip.  A quick look at the git
history didn't find any obviously-related patches, but certainly there
are enough bugs fixed between 9.3.0 and 9.3.3 that your first move ought
to be to upgrade.  If you can still reproduce this with 9.3.3 server
and pg_dump, please submit a *self contained* test case.  (The CREATE
TRIGGER statement alone is not that.  A SQL script to create a database
that exhibits the problem would do.)

            regards, tom lane