Message-ID: <dd4e17f5-0c42-49ac-92e9-2db648bb55b9@deepbluecap.com>
Date: Fri, 13 Sep 2024 10:58:46 +0200
MIME-Version: 1.0
User-Agent: Mozilla Thunderbird
Subject: Re: pg_restore with --disable-triggers discards ENABLE ALWAYS
To: Laurenz Albe <laurenz.albe@cybertec.at>, pgsql-bugs@lists.postgresql.org
References: <d374b6fc-4217-48a9-8639-2c9b4d3a92d0@deepbluecap.com>
 <78a13f951a03bf325027f8dcfb32b1b5089cdb14.camel@cybertec.at>
Content-Language: en-US
From: Duncan Sands <duncan.sands@deepbluecap.com>
In-Reply-To: <78a13f951a03bf325027f8dcfb32b1b5089cdb14.camel@cybertec.at>
Content-Type: text/plain; charset=UTF-8; format=flowed
Content-Transfer-Encoding: 8bit
Archived-At: 
 <https://www.postgresql.org/message-id/dd4e17f5-0c42-49ac-92e9-2db648bb55b9%40deepbluecap.com>
Precedence: bulk

Hi Laurenz,

On 12/09/2024 22:02, Laurenz Albe wrote:
> On Thu, 2024-09-12 at 10:27 +0200, Duncan Sands wrote:
>> CREATE TABLE test_table(x int);
>> CREATE FUNCTION test_function() RETURNS trigger AS $$ BEGIN RETURN NULL; END; $$
>> LANGUAGE plpgsql;
>> CREATE TRIGGER test_trigger AFTER UPDATE ON test_table FOR EACH ROW EXECUTE
>> FUNCTION test_function();
>> ALTER TABLE test_table ENABLE ALWAYS TRIGGER test_trigger;
>>
>> Checking the table:
>>
>> duncan=> \d test_table
>>                Table "public.test_table"
>>    Column |  Type   | Collation | Nullable | Default
>> --------+---------+-----------+----------+---------
>>    x      | integer |           |          |
>> Triggers firing always:
>>       test_trigger AFTER UPDATE ON test_table FOR EACH ROW EXECUTE FUNCTION
>> test_function()
>>
>> ^ Observe "Triggers firing always".
>>
>>
>> Now for the dump + restore:
>>
>> pg_dump -f dump.custom -Fc --table test_table
>> pg_restore --data-only --disable-triggers --dbname duncan dump.custom
>>
>> Checking the table:
>>
>> duncan=> \d test_table
>>                Table "public.test_table"
>>    Column |  Type   | Collation | Nullable | Default
>> --------+---------+-----------+----------+---------
>>    x      | integer |           |          |
>> Triggers:
>>       test_trigger AFTER UPDATE ON test_table FOR EACH ROW EXECUTE FUNCTION
>> test_function()
>>
>> ^ Observe that "Triggers firing always" has disappeared.
> 
> This looks like a user error to me.
> If you restore with --data-only, the table and constraint definitions
> are not restored at all.  So the table "test_table" in database "duncan"
> must already have existed before the restore, and the trigger was already
> defined like that.

No, the trigger was ENABLE ALWAYS when dumped, and restoring zapped that.  To 
confirm that it was ENABLE ALWAYS when dumped:

$ pg_restore -f - dump.custom | grep 'ENABLE ALWAYS'
ALTER TABLE public.test_table ENABLE ALWAYS TRIGGER test_trigger;


To summarize: the table existed before the restore, and the trigger was ENABLE 
ALWAYS at the moment it was dumped as shown in the steps to reproduce above: I 
create the table, make an ENABLE ALWAYS trigger, then dump the table, then 
restore the dump with --data-only and --disable-triggers.  At which point (in 
spite of --data-only) the table has been modified: the trigger is no longer an 
ENABLE ALWAYS trigger.

Best wishes, Duncan.