From the docs at
https://www.postgresql.org/docs/current/sql-set-transaction.html:
The SET TRANSACTION command sets the characteristics of the current
> transaction. It has no effect on any subsequent transactions. SET SESSION
> CHARACTERISTICS sets the default transaction characteristics for
> subsequent transactions of a session
In practical usage, I rarely use SET SESSION, I prefer to set it at the
transaction level.
For your demo, try also examining SHOW default_transaction_isolation;
Cheers,
Greg
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