Re: Add Pipelining support in psql

On Wed, 27 Nov 2024 at 13:05, Kirill Reshke <reshkekirill(at)gmail(dot)com> wrote:
> ```
> db1=# \startpipeline
> db1=# begin \parse p1
> db1=*#
> ```
> Notice the asterisks that appeared after parse the message. This
> typically indicates we are in the tx block. this is however untrue
> before the bind+exec message for p1 will be sent (\bind_name
> metacommand). Am I correct?

This behaviour is expected, it also happens if you send "SELECT 1"
instead of "begin" in the parse message:
db1=# \startpipeline
db1=# SELECT 1 \parse p1
db1=*#

The reason this happens is that the first command in a pipeline sent
to the server opens an implicit transaction. See the "implicit COMMIT"
wording here[1], or look at this code in exec_parse_message:

/*
* Start up a transaction command so we can run parse analysis etc. (Note
* that this will normally change current memory context.) Nothing happens
* if we are already in one. This also arms the statement timeout if
* necessary.
*/
start_xact_command();

[1]: https://www.postgresql.org/docs/current/protocol-flow.html#PROTOCOL-FLOW-PIPELINING