Re: further clarification: alter table alter column set not null - table scan is skipped
| От | David G. Johnston |
|---|---|
| Тема | Re: further clarification: alter table alter column set not null - table scan is skipped |
| Дата | |
| Msg-id | CAKFQuwbkV4yQU_5rHWwCfwSY3mjhh_jk50THwYEdRvwAZ36BRQ@mail.gmail.com обсуждение исходный текст |
| Ответ на | further clarification: alter table alter column set not null - table scan is skipped (PG Doc comments form <noreply@postgresql.org>) |
| Ответы |
Re: further clarification: alter table alter column set not null - table scan is skipped
|
| Список | pgsql-docs |
On Wed, Jul 30, 2025, 13:55 PG Doc comments form <noreply@postgresql.org> wrote:
The following documentation comment has been logged on the website:
Page: https://www.postgresql.org/docs/17/docguide.html
Description:
Hello there,
I like PostgreSQL a lot so this is my way of giving back.
The "table scan is skipped" optimization can use some clarification
https://www.postgresql.org/docs/current/sql-altertable.html#SQL-ALTERTABLE-DESC-SET-DROP-NOT-NULL
My proposal is "then the table scan is skipped if the alter statement
doesn't drop the constraint."
The reason behind the proposal is documented here
https://dev.to/andrewpsy/the-set-not-null-downtime-trap-in-postgresql-1o71
Thank you for working on such an awesome project.
Cheers,
Andrew
I'm kinda hoping this is actually just a fixable bug...
Otherwise I'd probably go for a parenthetical:
(however, the constraint used must not be dropped in the same alter table command).
David J.
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