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From: Bruce Momjian <[email protected]>
To: David G. Johnston <[email protected]>
Cc: [email protected]
Cc: Pg Docs <[email protected]>
Subject: Re: CREATE TABLE AS, section IF NOT EXISTS should clarify what happens to the data
Date: Mon, 18 Jul 2022 15:43:03 -0400
Message-ID: <[email protected]> (raw)
In-Reply-To: <CAKFQuwY30ro-xosyLZc=qFO3UhnudwvHO4oOJDqGawdQrtUWSA@mail.gmail.com>
References: <[email protected]>
	<[email protected]>
	<CAKFQuwY30ro-xosyLZc=qFO3UhnudwvHO4oOJDqGawdQrtUWSA@mail.gmail.com>

fOn Thu, Jul 14, 2022 at 06:47:19PM -0700, David G. Johnston wrote:
> Not only is the existing table not modified, I think that the select query
> portion of the command is never even executed.  That would seem to be useful
> knowledge to have.
> 
> Maybe something like:
> 
> <para>
>  Do not throw an error if a relation with the same name already exists.
>  A notice is issued in this case.
>  If <literal>WITH DATA</literal> is specified (the default) the execution of
> the parsed query does not happen, leaving the existing table with its existing
> contents.
> </para>

I tried to go in that direction, but couldn't clearly name the
SELECT/VALUES part of the CREATE TABLE AS query because CREATE TABLE
AS is also a query.  I felt trying to say we ran the CREATE TABLE AS
query but not the SELECT/VALUES of the query was just too confusing.  I
used "simply issue a notice" as implying that nothing else happens,
which I considered sufficient.
> 
> I've removed the xref to create table as there is nothing additional there of
> material benefit - the sentence:

Okay, removed.  Updated patch attached.

-- 
  Bruce Momjian  <[email protected]>        https://momjian.us
  EDB                                      https://enterprisedb.com

  Indecision is a decision.  Inaction is an action.  Mark Batterson



Attachments:

  [text/x-diff] exists.diff (767B, 2-exists.diff)
  download | inline diff:
diff --git a/doc/src/sgml/ref/create_table_as.sgml b/doc/src/sgml/ref/create_table_as.sgml
index 07558ab56c..8429333e3a 100644
--- a/doc/src/sgml/ref/create_table_as.sgml
+++ b/doc/src/sgml/ref/create_table_as.sgml
@@ -100,9 +100,8 @@ CREATE [ [ GLOBAL | LOCAL ] { TEMPORARY | TEMP } | UNLOGGED ] TABLE [ IF NOT EXI
     <term><literal>IF NOT EXISTS</literal></term>
     <listitem>
      <para>
-      Do not throw an error if a relation with the same name already exists.
-      A notice is issued in this case. Refer to <xref linkend="sql-createtable"/>
-      for details.
+      Do not throw an error if a relation with the same name already
+      exists; simply issue a notice and leave the table unmodified.
      </para>
     </listitem>
    </varlistentry>

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