Date: Mon, 29 Dec 2025 20:01:21 -0500
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Subject: Re: Combining metavariables and table names
To: pgsql-general@lists.postgresql.org
From: H <agents@meddatainc.com>
Message-ID: <60F4B5CE-F983-4174-A141-0C755284CDFD@meddatainc.com>
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Precedence: bulk

On December 28, 2025 10:41:19 PM EST, Tom Lane <tgl@sss=2Epgh=2Epa=2Eus> wr=
ote:
>"David G=2E Johnston" <david=2Eg=2Ejohnston@gmail=2Ecom> writes:
>> On Sunday, December 28, 2025, H <agents@meddatainc=2Ecom> wrote:
>>> I have a feeling I might be missing how to use the combination of a
>>> metavariable and a table name when used in an argument to a
>procedure=2E
>
>> No, what you are doing is impossible if you limit yourself to direct
>SQL
>> command syntax writing=2E
>
>Yeah :-(
>
>> I=E2=80=99d probably do something like:
>> versioning(=E2=80=A6, format(=E2=80=98%I=2E%I=E2=80=99, :=E2=80=99s=E2=
=80=99, =E2=80=98test_history=E2=80=99), =E2=80=A6)
>
>The reason this is hard is that we don't support expressions in
>CREATE TRIGGER, only simple literals=2E  So any such processing would
>have to be done in the client-side code that is sending the command,
>and I don't think psql's variable-substitution ability is quite up
>to the job=2E
>
>You might be able to make it work through the hacky method of
>supplying the schema name and table name as separate trigger
>arguments=2E
>
>Another idea could be to construct the desired string as a SELECT
>result, and then use \gexec=2E  There's a few too many moving parts
>in that for my taste, but maybe it could work=2E
>
>			regards, tom lane

That would explain it! I now see that when I read the CREATE TRIGGER docum=
entation=2E

I will use the workaround I found, ie=2E generating a literal string in an=
other meta variable=2E It would be nice if this would be considered a reque=
st for an enhancement?