Subject: Can "on delete cascade" dependency be used in pgdump or similar ?

From: dfgpostgres <[email-masked]>
Date: Fri, 27 Feb 2026 17:39:39 -0500

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 ?
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 !

---

From: "David G. Johnston" <[email-masked]>
Date: Fri, 27 Feb 2026 15:57:54 -0700

On Fri, Feb 27, 2026 at 3:40 PM dfgpostgres <[email-masked]> wrote:

>  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".
>

No, it cannot.

> (remembering that we do have the "on delete cascade" set up) ?
Nothing built into core.  The only additional feature you could leverage is
on delete triggers.  But you'd need some custom code for maintenance to
ensure all relevant tables have the cascade delete and on delete triggers.

David J.

---

From: Adrian Klaver <[email-masked]>
Date: Fri, 27 Feb 2026 15:13:52 -0800

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.
> 
> 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".
> 

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.

-- 
Adrian Klaver
[email-masked]

---

From: Justin Swanhart <[email-masked]>
Date: Sun, 1 Mar 2026 07:22:26 -0500

> (remembering that we do have the "on delete cascade" set up) ?

Hi,

I think a better way to approach this problem is using "change data
capture" using the WAL.  Projects such as Debezium [debezium.io] will allow
you to process the changes from the server and capture the deletions from
tables.  You can archive the deleted rows however you like.

--Justin