Re: My question about the transaction

By default, psql is configured with autocommit on.
Use another administrator, like phpadmin, and configure the connection with
autocommit off.

Atte
JRBM

El jue, 19 oct 2023 a las 11:49, Wen Yi (<wen-yi(at)qq(dot)com>) escribió:

> Hi community,
> I am learning the transaction of the postgresql, and I try to test using
> these:
>
> ######
>
> terminal 1:
>
> postgres=# select * from t;
> number
> --------
> 1
> (1 row)
>
> postgres=# update t set number = 2;
> UPDATE 1
> postgres=# select * from t;
> number
> --------
> 2
> (1 row)
>
> postgres=# select * from t;
> number
> --------
> 2
> (1 row)
>
> postgres=#
>
> ######
>
> terminal 2:
>
> postgres=# create table t (number integer);
> CREATE TABLE
> postgres=# insert into t values (1);
> INSERT 0 1
> postgres=# begin;
> BEGIN
> postgres=*# insert into t values (2);
> INSERT 0 1
> postgres=*# select * from t;
> number
> --------
> 2
> 2
> (2 rows)
>
> postgres=*# rollback;
> ROLLBACK
>
> My question is, in my view, the transaction model should make sure that
> when one on-process transaction don't commit itself, the data on this
> transaction shouldn't can be modified by other transaction(I the
> single-statement also be treated as a simple transaction), but why the
> update works?(I think terminal 1 will block until the terminal 2's
> transaction commit or rollback).
> Can someone share you opinion to me?
> Thanks in advance!
>
> Yours,
> Wen Yi
>
>
>