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Message-ID: <fdaa003e-919c-cbc9-4f0c-e4546e96bd65@gmail.com>
Date: Thu, 11 Apr 2024 15:00:00 +0300
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Subject: Re: Add SPLIT PARTITION/MERGE PARTITIONS commands
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To: Dmitry Koval <d.koval@postgrespro.ru>,
 Richard Guo <guofenglinux@gmail.com>
Cc: Alexander Korotkov <aekorotkov@gmail.com>,
 PostgreSQL Hackers <pgsql-hackers@lists.postgresql.org>
References: <c73a1746-0cd0-6bdd-6b23-3ae0b7c0c582@postgrespro.ru>
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From: Alexander Lakhin <exclusion@gmail.com>
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Hi Dmitry,

11.04.2024 11:59, Dmitry Koval wrote:
>
>> FWIW, I also proposed a patch earlier that fixes error messages and
>> comments in the split partition code
>
> Sorry, I thought all the fixes you suggested were already included in v1-0002-Fixes-for-english-text.patch (but they 
> are not).
> Added missing lines to v2-0002-Fixes-for-english-text.patch.
>

It seems to me that v2-0001-Fix-for-SPLIT-MERGE-partitions-of-temporary-table.patch
is not complete either.
Take a look, please:
CREATE TABLE t (i int) PARTITION BY RANGE (i);
SET search_path = pg_temp, public;
CREATE TABLE tp_0_1 PARTITION OF t
   FOR VALUES FROM (0) TO (1);
-- fails with:
ERROR:  cannot create a temporary relation as partition of permanent relation "t"

But:
CREATE TABLE t (i int) PARTITION BY RANGE (i);
CREATE TABLE tp_0_1 PARTITION OF t
   FOR VALUES FROM (0) TO (1);
CREATE TABLE tp_1_2 PARTITION OF t
   FOR VALUES FROM (1) TO (2);
INSERT INTO t VALUES(0), (1);
SELECT * FROM t;
-- the expected result is:
  i
---
  0
  1
(2 rows)

SET search_path = pg_temp, public;
ALTER TABLE t
MERGE PARTITIONS (tp_0_1, tp_1_2) INTO tp_0_2;
-- succeeds, and
\c -
SELECT * FROM t;
-- gives:
  i
---
(0 rows)

Please also ask your tech writers to check contents of src/test/sql/*, if
possible (perhaps, they'll fix "salesmans" and improve grammar).

Best regards,
Alexander
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    <div class="moz-cite-prefix">Hi Dmitry,<br>
      <br>
      11.04.2024 11:59, Dmitry Koval wrote:<br>
    </div>
    <blockquote type="cite"
      cite="mid:b907ce77-c054-4009-a871-4d55cb3f73f9@postgrespro.ru"><br>
      <blockquote type="cite">FWIW, I also proposed a patch earlier that
        fixes error messages and
        <br>
        comments in the split partition code
        <br>
      </blockquote>
      <br>
      Sorry, I thought all the fixes you suggested were already included
      in v1-0002-Fixes-for-english-text.patch (but they are not).
      <br>
      Added missing lines to v2-0002-Fixes-for-english-text.patch.
      <br>
      <br>
    </blockquote>
    <br>
    It seems to me that
    v2-0001-Fix-for-SPLIT-MERGE-partitions-of-temporary-table.patch<br>
    is not complete either.<br>
    Take a look, please:<br>
    CREATE TABLE t (i int) PARTITION BY RANGE (i);<br>
    SET search_path = pg_temp, public;<br>
    CREATE TABLE tp_0_1 PARTITION OF t <br>
      FOR VALUES FROM (0) TO (1);<br>
    -- fails with:<br>
    ERROR:  cannot create a temporary relation as partition of permanent
    relation "t"<br>
    <br>
    But:<br>
    CREATE TABLE t (i int) PARTITION BY RANGE (i);<br>
    CREATE TABLE tp_0_1 PARTITION OF t<br>
      FOR VALUES FROM (0) TO (1);<br>
    CREATE TABLE tp_1_2 PARTITION OF t<br>
      FOR VALUES FROM (1) TO (2);<br>
    INSERT INTO t VALUES(0), (1);<br>
    SELECT * FROM t;<br>
    -- the expected result is:<br>
     i <br>
    ---<br>
     0<br>
     1<br>
    (2 rows)<br>
    <br>
    SET search_path = pg_temp, public;<br>
    ALTER TABLE t<br>
    MERGE PARTITIONS (tp_0_1, tp_1_2) INTO tp_0_2;<br>
    -- succeeds, and<br>
    <span style="font-family:monospace"><span
        style="color:#000000;background-color:#ffffff;">\c -</span><br>
    </span>SELECT * FROM t;<br>
    -- gives:<br>
     i <br>
    ---<br>
    (0 rows)<br>
    <br>
    Please also ask your tech writers to check contents of
    src/test/sql/*, if<br>
    possible (perhaps, they'll fix "salesmans" and improve grammar).<br>
    <br>
    Best regards,<br>
    Alexander<br>
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