Στις 9/12/23 00:54, ο/η Tom Lane έγραψε:
Achilleas Mantzios <a.mantzios@xxxxxxxxxxxxxxxxxxxx> writes:
the trick is to have "application_name=" with no value. This causes the
server to not set application_name initially.
No, that sets it to an empty string, while application_name='' sets
it to two single quotes, according to the testing I did. In either
case, that value will be reported to the client as the active value
during connection start. Then the subsequent SET causes a new
report, but (since v14) only if the value being set is different.
Thank you Tom, now I see we have a different behavior, I have uploaded a
video that demonstrates my case : https://youtu.be/qcrVsFszV0Y
I didn't have the time to fire up wireshark/tcpdump or debugger thought
(I should).
Please check the scenario
Client C1 connects to S1, sets application_name. BEGINS, COMMITS, the
server gets freed to server the next client.
Client C2 connects to the same S1, sets application_name, and gets no
report back. So it stays with application_name empty. Then this breaks
the application.
How could pgbouncer prevent this from happening ?
pgbouncer would have to regurgitate the latest ParameterStatus
messages to the new client (during its faked-up initial connection
handshake) to ensure everything's synchronized correctly.
If for some reason it's not doing that, that would be a pretty
serious bug if you ask me, since clients might be relying on
hearing the truth about settings like client_encoding. Since
the whole point of pgbouncer is that the backend doesn't know
a new client has been slotted in, it's not clear to me how or
why the backend should solve this.
You helped a great deal! It is time I open an issue on the pgbouncer
project.
regards, tom lane
--
Achilleas Mantzios
IT DEV - HEAD
IT DEPT
Dynacom Tankers Mgmt
