You can still block vacuum from running if you have long running (or very aggressive) read transactions. I don’t think
theyare very helpful or performant from a Postgres engine perspective.
They can be helpful in application development because they will fail if devs attempt any mutations inside read only
(fromwhat I recall).
Sent from my iPhone
> On Jan 25, 2025, at 10:01 AM, Laurenz Albe <laurenz.albe@cybertec.at> wrote:
>
> On Sat, 2025-01-25 at 14:55 +0000, Edson Richter wrote:
>> -Connections are established using the jdbc "readonly" attribute.
>>
>> Does PostgreSQL perform any optimization on queries in this scenario to avoid
>> establishing locks? Or are these queries treated like any other?
>
> The only difference that I am aware of is that read-only transactions at the
> SERIALIZABLE isolation level can release predicate locks earlier, which can
> benefit performance.
>
> But I don't think that you need to worry: reading transactions only take an
> ACCESS SHARE lock on tables, which won't conflict with data modifications.
>
> Yours,
> Laurenz Albe
>
>
