Message-ID: <4df20e70-a083-4334-9548-5f8b9025847c@postgrespro.ru>
Date: Wed, 13 May 2026 23:47:13 +0300
MIME-Version: 1.0
User-Agent: Mozilla Thunderbird
Subject: Re: Fix SPLIT PARTITION bound-overlap bug and other improvements
To: Chao Li <li.evan.chao@gmail.com>,
 PostgreSQL-development <pgsql-hackers@postgresql.org>
Cc: Alexander Korotkov <aekorotkov@gmail.com>
References: <C18878AB-DEB2-4A61-9995-A035DD644B81@gmail.com>
Content-Language: en-US
From: Dmitry Koval <d.koval@postgrespro.ru>
In-Reply-To: <C18878AB-DEB2-4A61-9995-A035DD644B81@gmail.com>
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 <https://www.postgresql.org/message-id/4df20e70-a083-4334-9548-5f8b9025847c%40postgrespro.ru>
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Hi, Chao Li!

Thank you for the bug report, test script, and fix!

 >> 0. A bound-overlap bug

I think this fix should be applied without much discussion:
------------------------------------------------------------------------
diff --git a/src/backend/partitioning/partbounds.c 
b/src/backend/partitioning/partbounds.c
index 9b4277a4987..8b8f90569fe 100644
--- a/src/backend/partitioning/partbounds.c
+++ b/src/backend/partitioning/partbounds.c
@@ -5419,7 +5419,8 @@ check_partition_bounds_for_split_range(Relation 
parent,
                                                                 "ALTER 
TABLE ... SPLIT PARTITION"),
  
parser_errposition(pstate, exprLocation((Node *) datum)));
                 }
-               else
+
+               if (last)
                 {
                         PartitionRangeBound *split_upper;
------------------------------------------------------------------------

 >> 1. The documentation about splitting with a DEFAULT partition is a 
bit unclear
 >>  ...
 >> 2. I found this hint message confusing:
 >> ...

Unfortunately, I cannot comment on these points; it would be good to get 
the opinion of people who know English well.


 >> 3. SPLIT PARTITION currently provides another way to add a DEFAULT 
partition:
 >> ...

Agreed, this is another way to add a DEFAULT partition. But I'm not sure 
that this way should be disabled (using the special function 
check_split_partition_not_same_bound)...
Maybe it's better to keep it "as is"?

-- 
With best regards,
Dmitry Koval

Postgres Professional: http://postgrespro.com