Question on the format of datetime

[jiamo]

I use wal2json and psycopg2 to got postgresql data change. I have a question on the format of datatime. In psql I have column type timestamp with timezone

In psql console:

postgres=# select create_time from test limit 1;
          create_time
-------------------------------
 2018-05-18 03:06:22.446039+00

In some graph ide like DataGrip (after I click on the column)

create_time
2018-05-18 03:06:22.446039 +00:00

The wal2json return '2018-05-18 03:06:22.446039+00'. But I look at https://docs.python.org/3/library/datetime.html The %z is '+0000' have 4 digit.
Does I got some misunderstanding on the stand?

[eulerto]

@jiamo wal2json uses the same output as the corresponding data type. Take a look at backend/utils/adt/datetime.c, function EncodeTimezone. If the timezone have its minute part as zero, it is not printed (which means that -03:00 will be printed as -03 and -03:30 will be printed as -03:30 ). AFAIR ISO 8601 supports minutes omission in timezone specification (-07:00 is the same as -07 ).

The output depends on DateStyle parameter (read [1]).

postgres=# show DateStyle;
 DateStyle 
-----------
 ISO, MDY
(1 row)

postgres=# select now();
              now              
-------------------------------
 2018-05-23 02:56:06.535951+00
(1 row)

postgres=# set DateStyle to 'SQL';
SET
postgres=# select now();
              now               
--------------------------------
 05/23/2018 02:56:27.382021 UTC
(1 row)

postgres=# set DateStyle to 'Postgres';
SET
postgres=# select now();
                 now                 
-------------------------------------
 Wed May 23 02:56:37.656014 2018 UTC
(1 row)

[1] https://www.postgresql.org/docs/10/static/datatype-datetime.html#DATATYPE-DATETIME-OUTPUT

[jiamo]

I got it.