How do I set Google Cloud SQL - PostgreSQL timezone to UTC - postgresql

I see Cloud SQL - MySQL has a Database Flag to set the default_time_zone. I cannot however, find how to do the same for Cloud SQL - PostgreSQL. I need my time zone to be UTC.


The flags that you see in Cloud SQL - MySQL in Configuring Database Flags documentation are provided by MySQL. If you click on the flag default_time_zone that you are referring to, then you will see that you will be redirected to MySQL documentation page. For the Cloud SQL - PostgreSQL the flags that you see in the Configuring Database Flags documentation, are provided by PostgreSQL, therefore they don't expose this flag or any similar flag like this.
To change the timezone of the PostgreSQL instance, you have to SSH into it and do it by executing query:
Go to the SQL page on the console and find your PostgreSQL instance.
On the instance's details record you will find three dots at the end. Click and select the option Connect VM. On the right side of your window you will see a tutorial.
Follow the tutorial steps to set up a Compute Engine VM Instance that will be connecting to your PostgreSQL.
After you finish all the steps form the tutorial. Go to the Compute Engine page and SSH to the instance that you created for connecting to the PostgreSQL.
Execute the psql "sslmode=disable dbname=postgres user=postgres hostaddr=[POSTGRESQL_PUBLIC_IP]" to connect to the instance.
Execute the SELECT NOW(); to see the current timezone, that your PostgreSQL is running at.
Execute the SET timezone to 'UTC'; to set the timezone of the PostgreSQL to UTC.
Execute the SELECT NOW(); to verify that the default timezone server updated successfully.
You can also connect to the PostgreSQL from Cloud Shell and skip the part of the VM Instance creation.

Related

PostgreSQL 11.16 cannot execute CREATE TABLE in a read-only transaction

I have a PostgreSQL database running on an Azure machine. When I try to create a table on a database, I get an error "cannot execute CREATE TABLE in a read-only transaction". The SQL query is being executed by a python script using a sqlalchemy engine. But I tried a similar query in PGAdmin installed on my machine and I get the same error. And I noticed that I do not have this issue if I connect to the database from a colleague's machine.
After further research, I found that if I execute SELECT pg_is_in_recovery(); in my PGAdmin, it returns true. And false on my colleague's machine.
Let me know if there is any way to correct this

SELECT pg_is_in_recovery() - returned true = Database has only Read Acces
can you check your permission?
you can check postgresql.conf file and atribute default_transaction_read_only
or try this:
begin;
set transaction read write;
alter database exercises set default_transaction_read_only = off;
commit;

The issue was that our posgtresql machine is a HA machine, and that I was connecting to an IP address rather than the domain.

PostgreSQL - Incorrect time

I have a database that is deployed in GCP. I connect to DB via the GCP console and use Dbeaver to run queries. When I run SELECT NOW(); it's showing the time at which I started the session and not the current time.

Looks like you started a TRANSACTION and NOW() shows you the time the transaction started. You have 2 option to solve this issue:
Don't use a transaction and you can work with NOW()
Or inside a transaction, use CLOCK_TIMESTAMP()
See also the manual about this behaviour.

Oracle READ WRITE mode in postgres

I am migrating Oracle database to Postgres Aurora. There is one Oracle PL/SQL block which checks if the database is in read write open mode. Below is the query like:
Select open_mode into v_open_mode from v$database;
if v_open_mode = 'READ WRITE' then
-- perform some steps.
I want to know if we have any equivalent query in Postgres. Or even if I can know the postgres node is WRITE mode.
I am also open to get anything which is native to Aurora which show if the node is reader or writer.

I am not sure what the Oracle thing does, but I assume the closest thing would be to check if Postgres is in recovery mode using pg_is_in_recovery()
So something like:
if not pg_is_in_recovery() then
-- do some steps
end if;
That is from "stock" Postgres, I don't know if Amazon Aurora does anything different or provides other functions.

How to set timezone on postgresql jdbc connection created by flyway?

I have a postgresql database that I deploy scripts to using flyway. I use the maven flyway plugin to launch the database build against the target database. In that build I have scripts that do things like:
create table my_table(
my_date_time timestamp with time zone not null
);
insert into my_table(my_date_time)
select '2000-01-01';
The postgresql database timezone is set to UTC. My client machine (that runs the maven/flyway build) is running CEST (UTC+2:00).
When the scripts run, the database interprets the string literal above as '1999-12-31 22:00:00+00:00' and writes that to storage.
It seems that the jdbc client connection created by flyway is not setting its client timezone to UTC, but is taking the timstamp string and interpreting it as '2000-01-01 00:00:00+02:00'.
How can I set the client timezone on the jdbc connection created by flyway to UTC? Is there a setting that can be placed in my flyway.conf file?
If I change my local machine timezone to UTC the problem goes away, but I'd rather not do that on my development workstation.

A colleague suggested the following
mvn -Duser.timezone=UTC flyway:migrate

Instead of just giving it a date, which postgres has to interpret, it would be better to fully specify the timestamp:
insert into my_table(my_date_time)
select '2000-01-01T00:00:00+00';
If that is not possible, you could try running mvn with -Duser.timezone=UTC but fully specifying the timestamp is the better option as it leaves no room for misinterpretation or misconfiguration.

Another way is to set session timezone in migration script itself
SET timezone TO 'UTC';

i use flyway CLI in a script. so setting correct timezone to the corresponding environment variable before executing flyway command works for me:
export TZ=GMT

ERROR: cannot execute CREATE TABLE in a read-only transaction

I'm trying to setup the pgexercises data in my local machine. When I run: psql -U <username> -f clubdata.sql -d postgres -x I get the error: psql:clubdata.sql:6: ERROR: cannot execute CREATE SCHEMA in a read-only transaction.
Why did it create a read-only database on my local machine? Can I change this?

Normally the most plausible reasons for this kind of error are :
trying create statements on a read-only replica (the entire instance is read-only).
<username> has default_transaction_read_only set to ON
the database has default_transaction_read_only set to ON
The script mentioned has in its first lines:
CREATE DATABASE exercises;
\c exercises
CREATE SCHEMA cd;
and you report that the error happens with CREATE SCHEMA at line 6, not before.
That means that the CREATE DATABASE does work, when run by <username>.
And it wouldn't work if any of the reasons above was directly applicable.
One possibility that would technically explain this would be that default_transaction_read_only would be ON in the postgresql.conf file, and set to OFF for the database postgres, the one that the invocation of psql connects to, through an ALTER DATABASE statement that supersedes the configuration file.
That would be why CREATE DATABASE works, but then as soon as it connects to a different database with \c, the default_transaction_read_only setting of the session would flip to ON.
But of course that would be a pretty weird and unusual configuration.

Reached out to pgexercises.com and they were able to help me.
I ran these commands(separately):
psql -U <username> -d postgres
begin;
set transaction read write;
alter database exercises set default_transaction_read_only = off;
commit;
\q
Then I dropped the database from the terminal dropdb exercises and ran script again psql -U <username> -f clubdata.sql -d postgres -x -q

I was having getting cannot execute CREATE TABLE in a read-only transaction, cannot execute DELETE TABLE in a read-only transaction and others.
They all followed a cannot execute INSERT in a read-only transaction. It was like the connection had switched itself over to read-only in the middle of my batch processing.
Turns out, I was running out of storage!
Write access was disabled when the database could no longer write anything. I am using Postgres on Azure. I don't know if the same effect would happen if I was on a dedicated server.

I had same issue for Postgre Update statement
SQL Error: 0, SQLState: 25006 ERROR: cannot execute UPDATE in a read-only transaction
Verified Database access by running below query and it will return either true or false
SELECT pg_is_in_recovery()
true -> Database has only Read Access
false -> Database has full Access
if returns true then check with DBA team for the full access and also try for ping in command prompt and ensure the connectivity.
ping <database hostname or dns>
Also verify if you have primary and standby node for the database

In my case I had a master and replication nodes, and the master node became replication node, which I believe switched it into hot_standby mode. So I was trying to write data into a node that was meant only for reading, therefore the "read-only" problem.
You can query the node in question with SELECT pg_is_in_recovery(), and if it returns True then it is "read-only", and I suppose you should switch to using whatever master node you have now.
I got this information from: https://serverfault.com/questions/630753/how-to-change-postgresql-database-from-read-only-to-writable.
So full credit and my thanks goes to Craig Ringer!

Dbeaver: In my case
This was on.

This doesn't quite answer the original question, but I received the same error and found this page, which ultimately led to a fix.
My issue was trying to run a function with temp tables being created and dropped. The function was created with SECURITY DEFINER privileges, and the user had access locally.
In a different environment, I received the cannot execute DROP TABLE in a read-only transaction error message. This environment was AWS Aurora, and by default, non-admin developers were given read-only privileges. Their server connections were thus set up to use the read-only node of Aurora (-ro- is in the connection url), which must put the connection in the read-only state. Running the same function with the same user against the write node worked.
Seems like a good use case for table variables like SQL Server has! Or, at least, AWS should modify their flow to allow temp tables to be created and dropped on read nodes.

This occurred when I was restoring a production database locally, the database is still doing online recovery from the WAL records.
A little bit unexpected as I assumed pgbackgrest was creating instantly recoverable restores, perhaps not.
91902 postgres 20 0 1445256 14804 13180 D 4.3 0.3 0:28.06 postgres: startup recovering 000000010000001E000000A5

If like me you are trying to create DB on heroku and are stuck as this message shows up on the dataclip tab
I did this,
Choose Resources from(Overview Resources Deploy Metrics Activity Access Settings)
Choose Settings out of (Overview, Durability, Settings, Dataclip)
Then in Administration->Database Credentials choose View Credentials...
then open terminal and fill that info here and enter
psql --host=***************.amazonaws.com --port=5432 --username=*********pubxl --password --dbname=*******lol
then it'll ask for password, copy-paste from there and you can run Postgres cmds.

I suddenly started facing this error on postgres installed on my windows machine, when I was running alter query from dbeaver, all I did was deleted the connection of postgres from dbeaver and created a new connection

If you are using Azure Database for PostgreSQL your server gets into read-only mode when the storage used is near total capacity.
The error you get is exactly:
ERROR: cannot execute XXXXXXXXX in a read-only transaction
https://learn.microsoft.com/en-us/azure/postgresql/flexible-server/concepts-compute-storage

I just had this error. My cause was not granting permission to the SEQUENCE
GRANT ALL ON SEQUENCE word_mash_word_cube_template_description_reference_seq TO ronshome_user;

If you are facing this issue with an RDS instance cluster, please check your endpoint and use the Writer instance endpoint. Then it should work now.

Issue can be dur to Intellij config:
Go to Database view> click on Data Source Properties (Shift + enter)> (Select your data source)>
Options tab> Under Connection : uncheck Read-only

For me it was Azure PostgreSQL failing over to standby during maintaince in Azure and never failing back to master when PostgreSQL was in HA mode. You can check this event in Service Health and also check which zone you current VM is running from. If it's 2 and not 1 them most likely that's the result of events described above.