From: Tom Lane <tgl@sss.pgh.pa.us>
To: "David G. Johnston" <david.g.johnston@gmail.com>
cc: JORGE MALDONADO <jorgemal1960@gmail.com>,
        "pgsql-sql@postgresql.org" <pgsql-sql@postgresql.org>
Subject: Re: A situation with one parent table and 3 child tables
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Comments: In-reply-to "David G. Johnston" <david.g.johnston@gmail.com>
	message dated "Mon, 02 Oct 2023 19:53:54 -0700"
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Date: Mon, 02 Oct 2023 23:03:04 -0400
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"David G. Johnston" <david.g.johnston@gmail.com> writes:
> On Monday, October 2, 2023, JORGE MALDONADO <jorgemal1960@gmail.com> wro=
te:
>> I have one parent table (*table_p*) with 3 child tables (*table_ch1*, *=
table_ch2
>> *and *table_ch3*). Each record of the parent table can be associated wi=
th
>> 1 and only 1 child table records. This means that:
>> =

>> * Some records of the *table_p* will link to records of *table_ch1*
>> * Some records of the *table_p* will link to records of *table_ch2*
>> * Some records of the *table_p* will link to records of *table_ch3*
>> =

>> At first look, this does not make very much sense to me. I thought abou=
t
>> considering 3 parent tables, one for each child table. However, the 3
>> parent tables would have the same exact structure and I would like to k=
now
>> if there is a workaround for this issue.

> You are thinking of it backwards.  Your chN tables will have FK pointing
> back to the p table.  I suggest adding some kind of type column to the p
> table indicating which chN table the row belongs to.

Do you need that?  I was wondering about converting the 3 child tables
into a partitioned table.  Then you can query them separately when
you need to, but you can also treat them as one table --- and you
can set up one FK constraint between that and the parent table.

			regards, tom lane