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Subject: Re: Gaps in PK sequence numbers
From: Christophe Pettus <xof@thebuild.com>
In-Reply-To: <35fd10ab-5f7f-7a57-9cc5-c03d81476d13@appl-ecosys.com>
Date: Mon, 10 Jun 2024 16:05:30 -0700
Cc: pgsql-general@lists.postgresql.org
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To: Rich Shepard <rshepard@appl-ecosys.com>
Archived-At: <https://www.postgresql.org/message-id/DB68A3C3-FCF6-4815-9C5C-A77310B66474%40thebuild.com>
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> On Jun 10, 2024, at 15:57, Rich Shepard <rshepard@appl-ecosys.com> =
wrote:
> When I tried inserting new rows in the companies table psql told me =
that PK
> value 2310 already existed. Selecting max(PK) returned 2341. When =
entering
> multiple new rows is there a way to ignore gaps?

Strictly speaking, the sequence underlying nextval() has no idea what =
primary keys are or are not in use.  It's just a transaction-ignoring =
counter that increases with each nextval() call.  The only reason that =
you'd get duplicate key errors in this case are:

1. The sequence was reset to a different, lower value.
2. Rows were inserted that didn't use the sequence to select a primary =
key.