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help / color / mirror / Atom feedFrom: Zhenwei Shang <[email protected]>
To: Kirill Reshke <[email protected]>
Cc: Chao Li <[email protected]>
Cc: PostgreSQL-development <[email protected]>
Cc: Dmitry Koval <[email protected]>
Cc: Alexander Korotkov <[email protected]>
Subject: Re: Fix SPLIT PARTITION bound-overlap bug and other improvements
Date: Wed, 13 May 2026 17:32:09 +0800
Message-ID: <CABv9HUmYhtCWWmq1vAqY79bNncDA07ZSVV=Ryg3y0s9usNQWNw@mail.gmail.com> (raw)
In-Reply-To: <CALdSSPhquxjxisujDcfLqfoY2=SnUAHhsqgM9PvO0uO3uZC9jQ@mail.gmail.com>
References: <[email protected]>
<CALdSSPhquxjxisujDcfLqfoY2=SnUAHhsqgM9PvO0uO3uZC9jQ@mail.gmail.com>
Kirill Reshke <[email protected]> 于2026年5月13日周三 13:08写道：
> On Wed, 13 May 2026 at 09:39, Chao Li <[email protected]> wrote:
> >
> > Hi,
> >
> > While testing ALTER TABLE ... SPLIT PARTITION, I found a bug and a few
> behaviors and messages that seem worth improving.
> >
> > 0. A bound-overlap bug
> >
> > I numbered this item as 0 because I found it after finishing items 1, 2,
> and 3. While doing a final verification before sending this email, I was
> surprised to find that the partitioned table ended up with two overlapping
> partitions.
> >
> > Here is a simple repro:
> > ```
> > evantest=# drop table t;
> > DROP TABLE
> > evantest=# CREATE TABLE t (i int) PARTITION BY RANGE(i);
> > CREATE TABLE
> > evantest=# CREATE TABLE p0a PARTITION OF t FOR VALUES FROM (0) TO (51);
> > CREATE TABLE
> > evantest=# CREATE TABLE p0b PARTITION OF t FOR VALUES FROM (51) TO (100);
> > CREATE TABLE
> > evantest=# \d+ t;
> > Partitioned table "public.t"
> > Column | Type | Collation | Nullable | Default | Storage |
> Compression | Stats target | Description
> >
> --------+---------+-----------+----------+---------+---------+-------------+--------------+-------------
> > i | integer | | | | plain |
> | |
> > Partition key: RANGE (i)
> > Partitions:
> > p0a FOR VALUES FROM (0) TO (51)
> > p0b FOR VALUES FROM (51) TO (100)
> >
> > evantest=# ALTER TABLE t SPLIT PARTITION p0a INTO
> > evantest-# (PARTITION p0a FOR VALUES FROM (0) TO (53),
> > evantest(# PARTITION pdef DEFAULT);
> > ALTER TABLE
> > evantest=#
> > evantest=#
> > evantest=# \d+ t;
> > Partitioned table "public.t"
> > Column | Type | Collation | Nullable | Default | Storage |
> Compression | Stats target | Description
> >
> --------+---------+-----------+----------+---------+---------+-------------+--------------+-------------
> > i | integer | | | | plain |
> | |
> > Partition key: RANGE (i)
> > Partitions:
> > p0a FOR VALUES FROM (0) TO (53)
> > p0b FOR VALUES FROM (51) TO (100)
> > pdef DEFAULT
> > ```
> >
> > As shown above, p0a and p0b now overlap. I think this is a real bug.
>
>
> that's 100% real issue because of planner partition pruning
>
> ```
> reshke=# CREATE TABLE t (i int) PARTITION BY RANGE(i);
> CREATE TABLE
> reshke=# CREATE TABLE p0a PARTITION OF t FOR VALUES FROM (0) TO (51);
> CREATE TABLE
> reshke=# insert into t values (50);
> INSERT 0 1
> reshke=# CREATE TABLE p0b PARTITION OF t FOR VALUES FROM (51) TO (100);
> CREATE TABLE
> reshke=# insert into t values (51);
> INSERT 0 1
> reshke=# insert into t values (51);
> INSERT 0 1
> reshke=# insert into t values (51);
> INSERT 0 1
> reshke=# ALTER TABLE t SPLIT PARTITION p0a INTO(PARTITION p0a FOR
> VALUES FROM (0) TO (53),PARTITION pdef DEFAULT);
> ALTER TABLE
> reshke=# table t;
> i
> ----
> 50
> 51
> 51
> 51
> (4 rows)
> reshke=# select * from t where i = 51;
> i
> ---
> (0 rows)
>
> reshke=# set enable_partition_pruning to off;
> SET
> reshke=# select * from t where i = 51;
> i
> ----
> 51
> 51
> 51
> (3 rows)
>
> reshke=#
> ``
>
>
>
> --
> Best regards,
> Kirill Reshke
>
>
> I agree this is a bug. I applied the patch locally and confirmed the bug
is fixed with the patch.
Overall, the patch looks good to me.
Regards,
Zhenwei Shang
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Subject: Re: Fix SPLIT PARTITION bound-overlap bug and other improvements
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