Re: COPY ON_CONFLICT TABLE; save duplicated record to another table.

From: jian he <jian(dot)universality(at)gmail(dot)com>
To: Zsolt Parragi <zsolt(dot)parragi(at)percona(dot)com>, Jim Jones <jim(dot)jones(at)uni-muenster(dot)de>
Cc: PostgreSQL-development <pgsql-hackers(at)postgresql(dot)org>
Subject: Re: COPY ON_CONFLICT TABLE; save duplicated record to another table.
Date: 2026-05-11 03:13:15
Message-ID: CACJufxHjjhshvXC8jOMyry73AYMESTVLfQwto0=NK_A951exAA@mail.gmail.com
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Hi.

The attached patch should address most, if not all, of the issues you
both raised.

As explained in [1], we can export ExecInsert to let it perform the
main insertion work.
To allow ExecInsert to handle the remaining tasks, we need to carefuly manage
the lifecycle of constructed CopyFromStateData->ModifyTableContext (including
ModifyTableContext->EState): populate it, use it, and then release it.

Since ExecInsert already contains the necessary infrastructure for INSERT ON
CONFLICT DO NOTHING/SELECT, exporting it avoids duplicating that logic in
src/backend/commands/copyfrom.c (which is what v1 of the patch did).

[1]: https://postgr.es/m/CACJufxH_NbPuA+O5YR7xP4xDZ+iHkO2VFkddhrhBz+4-EUTp7w@mail.gmail.com

The exclusion unique constraint issue is still not resolved.... but,
overall v2 is better than v1, IMHO.

--
jian
https://www.enterprisedb.com/

Attachment Content-Type Size
v2-0002-COPY-ON_CONFLICT-TABLE.patch text/x-patch 58.5 KB
v2-0001-export-ExecInsert.patch text/x-patch 4.7 KB

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