Re: altering a column's collation leaves an invalid foreign key - Mailing list pgsql-hackers

On Thu, Nov 14, 2024 at 4:04 PM Peter Eisentraut <peter@eisentraut.org> wrote:

> I propose that I go ahead with committing the v7 patch (with your typo
> fixes) and then we continue discussing these other issues afterwards in
> a separate thread.
>
looks good to me.

but in create_table.sgml
     <para>
      In addition, when the data in the referenced columns is changed,
      certain actions are performed on the data in this table's
      columns.
<para/>
I actually want to add a sentence like:

      If the references columns collation is indeterministic, we use
bitwise comparison to
      check if the referenced columns data is being changed.


searching the internet found out:
— ON UPDATE RESTRICT: any change to a referenced column in the
referenced table is prohibited if there
is a matching row.
— ON UPDATE NO ACTION (the default): there is no referential update
action; the referential constraint
only specifies a constraint check.
NOTE 53 — Even if constraint checking is not deferred, ON UPDATE
RESTRICT is a stricter condition than ON UPDATE NO
ACTION. ON UPDATE RESTRICT prohibits an update to a particular row if
there are any matching rows; ON UPDATE NO
ACTION does not perform its constraint check until the entire set of
rows to be updated has been processed.

looking at NOTE 53, overall i think i get it.