Re: SELECT INTO deprecation

From: Peter Eisentraut <peter(dot)eisentraut(at)enterprisedb(dot)com>
To: Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us>
Cc: Michael Paquier <michael(at)paquier(dot)xyz>, Stephen Frost <sfrost(at)snowman(dot)net>, pgsql-hackers <pgsql-hackers(at)postgresql(dot)org>
Subject: Re: SELECT INTO deprecation
Date: 2020-12-09 20:48:54
Message-ID: 737048bf-de51-3fd4-bbcc-89f6d2bd2c4f@enterprisedb.com
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On 2020-12-03 20:26, Peter Eisentraut wrote:
> On 2020-12-03 16:34, Tom Lane wrote:
>> As I recall, a whole lot of the pain we have with INTO has to do
>> with the semantics we've chosen for INTO in a set-operation nest.
>> We think you can write something like
>>
>> SELECT ... INTO foo FROM ... UNION SELECT ... FROM ...
>>
>> but we insist on the INTO being in the first component SELECT.
>> I'd like to know exactly how much of that messiness is shared
>> by SQL Server.
>
> On sqlfiddle.com, this works:
>
> select a into t3 from t1 union select a from t2;
>
> but this gets an error:
>
> select a from t1 union select a into t4 from t2;
>
> SELECT INTO must be the first query in a statement containing a UNION,
> INTERSECT or EXCEPT operator.

So, with that in mind, here is an alternative proposal that points out
that SELECT INTO has some use for compatibility.

Attachment Content-Type Size
v2-0001-Remove-gratuitous-uses-of-deprecated-SELECT-INTO.patch text/plain 11.6 KB
v2-0002-doc-Clarify-status-of-SELECT-INTO-on-reference-pa.patch text/plain 1.9 KB

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