On Wed, 2024-10-09 at 18:07 +0800, iseki zero wrote:
> I found it difficult to understanding some paragraph in the document
> "Concurrency control" section.
>
> > The Repeatable Read mode provides a rigorous guarantee that each
> transaction sees a completely stable view of the database. However, this
> view will not necessarily always be consistent with some serial (one at
> a time) execution of concurrent transactions of the same level. For
> example, even a read-only transaction at this level may see a control
> record updated to show that a batch has been completed but/not/see one
> of the detail records which is logically part of the batch because it
> read an earlier revision of the control record. Attempts to enforce
> business rules by transactions running at this isolation level are not
> likely to work correctly without careful use of explicit locks to block
> conflicting transactions.
>
> At:
>
https://www.postgresql.org/docs/17/transaction-iso.html#XACT-REPEATABLE-READ:~:text=The%20Repeatable%20Read%20mode,to%20block%20conflicting%20transactions.
>
> Specifically, I can't understand the example.
I think this is referring to this example:
https://wiki.postgresql.org/wiki/SSI#Deposit_Report
Yours,
Laurenz Albe
