From: Tom Lane <tgl@sss.pgh.pa.us>
To: shihao zhong <zhong950419@gmail.com>
Cc: Bruce Momjian <bruce@momjian.us>
Cc: PostgreSQL-development <pgsql-hackers@lists.postgresql.org>
Subject: Re: First draft of PG 19 release notes
Date: Sat, 17 Oct 2026 00:13:00 -0400
Message-ID: <3382929.1792210380@sss.pgh.pa.us> (raw)
In-Reply-To: <CAGRkXqSsSL=5qXYymzN+D8hPZcBZGuEcT+5zF+MXE0KL_7Kxtg@mail.gmail.com>
References: <ad7ngXC125AvNqC2@momjian.us>
<5973.1791788107@localhost>
<as1_bGM_HKFA6HOs@momjian.us>
<CAGRkXqSsSL=5qXYymzN+D8hPZcBZGuEcT+5zF+MXE0KL_7Kxtg@mail.gmail.com>
shihao zhong <zhong950419@gmail.com> writes:
> 4. The hash join change (1811f1af98f) can write outer rows with NULL
> keys to a temp file, even with one batch. A LEFT JOIN with 297000 NULL
> keys wrote 33 MB of temp files, 18.6 wrote none. With temp_file_limit at
> 1MB it fails.
I'm a bit skeptical about this one. The older code would have
put those rows into the primary hash table rather than a dedicated
tuplestore, but either way you risk having to dump them to disk.
regards, tom lane
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To: pgsql-hackers@postgresql.org
Cc: tgl@sss.pgh.pa.us, zhong950419@gmail.com, bruce@momjian.us, pgsql-hackers@lists.postgresql.org
Subject: Re: First draft of PG 19 release notes
In-Reply-To: <3382929.1792210380@sss.pgh.pa.us>
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