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Message-ID: <666bc91c-d5df-4a61-aa3a-30fb1e1c9fcb@aklaver.com>
Date: Fri, 27 Feb 2026 15:13:52 -0800
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Subject: Re: Can "on delete cascade" dependency be used in pgdump or similar ?
To: dfgpostgres <dfgpostgres3@gmail.com>, pgsql-general@lists.postgresql.org
References: <CAAcmDX_zrfbQ2ixpGH_92SqeM=OJs5wPuW2_F-P+SefjoQGUOQ@mail.gmail.com>
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From: Adrian Klaver <adrian.klaver@aklaver.com>
In-Reply-To: <CAAcmDX_zrfbQ2ixpGH_92SqeM=OJs5wPuW2_F-P+SefjoQGUOQ@mail.gmail.com>
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On 2/27/26 2:39 PM, dfgpostgres wrote:
> pg 15.15 on linux
> 
> I have a DB with a table called "projects" which has a primary key 
> column called "project".  Other child tables are linked in a primary/ 
> foreign key relationship to "projects" with "on delete cascade".  Each 
> of those may have grandchild tables linked in via other primary/foreign 
> key relationships, all with the "on delete cascade".  Etc... .  If I 
> delete project "a", it'll cascade delete the children,  grandchild, 
> etc...  recs.  All traces of project "a" will be gone.
> 
> But I don't really want to lose the data from project "a", I want to 
> archive it in another DB (same DB server, different DB).  The brain-numb 
> method I've been using thus far is to copy the whole DB via pgdump then 
> use that to create the DB "a_archive".  Then (here's the wasteful part) 
> basically delete all the projects in "a-archive" EXCEPT for project 
> "a".  Then, when that's done, go to the main DB and delete project "a". 
> In effect, I just archived all the data for project "a" and put it in 
> the DB called "a_archive".while relieving the main DB of the project "a" 
> data. But what would be really neat is to leverage that cascade on 
> delete stuff to just pgdump project "a" and use that to create "a_archive".
> 
> Can pgdump do something like that ?

The best you can do, with pg_dump, is use:

https://www.postgresql.org/docs/current/app-pgdump.html

--table=pattern

     Dump only tables with names matching pattern. Multiple tables can 
be selected by writing multiple -t switches.

Though it will be up to you to make sure all the related tables are 
present in the dump.

Also depending on how things are setup you might be able to use logical 
replication:

https://www.postgresql.org/docs/current/logical-replication.html

In either case you still have to clean out the original database.


> Is there a better way to approach this problem of archiving one project 
> (remembering that we do have the "on delete cascade" set up) ?
> 
> Thanks in Advance !
> 


-- 
Adrian Klaver
adrian.klaver@aklaver.com