I want to turn on logging of all SQL statements that modify the database. I could get that on my own machine by setting the log_statement flag in the configuration file, but it needs to be enabled on the user's machine. How do you enable it from program code? (I'm using Python with psycopg2 if it matters.)
Turning on logging of SQL statements that modify the database can be achieved by:
ALTER SYSTEM SET log_statement TO 'mod';
-- Make it effective by triggering configuration reload (no server restart required).
SELECT pg_reload_conf();
-- To make sure the modification is not limited to the current session scope
-- it is better to log out from postgresql and log back in.
-- Check value of log_statement configuration, expected: mod
SELECT * FROM pg_settings WHERE name = 'log_statement';
This requires superuser access rights.
Check hereafter links to documentation for more details:
ALTER SYSTEM
pg_reload_conf()
The "it needs to be enabled on the user's machine" phrase is confusing, indeed... I assume you mean "from the user (client) side".
In Postgresql some server run-time parameters can be changed from a connection, but only from a superuser - and only for those settings that do not require a server restart.
I'm not sure if that includes the many log options. You might try with something like:
SELECT set_config('log_XXX', 'off', false);
where log_XXX is to be replaced by the respective logging setting, and 'false' by the value you want to set.
If that does not work, I guess you are out of luck.
Related
I'm wondering if it's possible to have psql start a transaction automatically when I open a psql session on the command line. I know I can start a transaction manually using 'BEGIN;' but I'm wondering if that can be done automatically without me typing in 'BEGIN;' manually on the command line.
Thanks!
I did a google search but that didn't come up with any good results.
You cannot have psql start a transaction when you login, but you can have it start a transaction with the first SQL statement you enter. For that, put a .psqlrc file into your home directory and give it the following content:
\set AUTOCOMMIT off
Note that that is a very bad idea (in my personal opinion). You are running the risk to inadvertently start a transaction that holds locks and blocks the progress of autovacuum. I have seen more than one PostgreSQL instance that suffered serious damage because of administrators who disabled autocommit in their interactive clients and kept transactions open. At the very least, add the following to your .psqlrc:
SET idle_in_transaction_session_timeout = '1min';
I installed Postgres
and followed the instruction. I create a database and logged in by the master password but I don't find the database even the + mark is not shown in the servers. can anyone help, please?
Unlike in pgAdmin3, with pgAdmin4,here you have to manually connect to a running postgres server andyou already have your specific database (DB) created.
So to set the stage, make sure you have the postgres server is running, and that you have created that DB already too.
Notice (in the image) that I CREATE database XYZ and GRANT all privileges to default user postgres. (Note; to work properly with pgAdmin4, you have to create a user called postgres in order to be able to connect with and log in to pgAdmin4.)
Then here are some quick steps to follow:
When within pgAdmin4, right-click the Servers option and select create.
Note:
In the image you'll see (1) next to "Servers" because I have done this process already. Kindly ignore that).
Select "server group" if you have many servers that you want to better manage. For most basic use cases, go ahead and select "server" (like I did).
For either option you select above, you'll get a pop-box to complete the "connection process". I selected "server" which is appropriate for your use case (see image below).
Note:
"name" field is required
As you can see already, enter a name (I went with "postgres" since it's what I was used to by default in pgAdmin3, but you can enter any name).
Notice the "connect now" checkbox is checked by default so as soon as the process is successful, your DB should display in the sidemenu. (This is a key to confirm that you entered the right info). But you can always uncheck this, to connect later.
Now, click connection tab and you see the image below.
The key fields to fill here, to keep it simple, are host name/address and password. Remember to save after entering your info.
Note:
If on connecting to local machine, localhost or http://127.0.0.1 should do. (I did "localhost")
If connecting to a DB instance in the cloud e.g. AWS, enter the endpoint in the host space. Here's more from AWS
A lot of the other fields have the default settings used when installing postgres and pgAdmin.
If you followed the steps above properly, then you should see something like this after you save.
Here's a good guide from the pgAdmin documentation
In case you created your database as template CREATE DATABASE ... IS_TEMPLATE =true, then the database is considered as "system object" and is not shown in the list if PgAdmin4 option "Show system objects?" is set to false.
Try menu File -> Preferences, in the tree find Browser -> Display, and the option is at the bottom.
Another option is to remove the template option:
ALTER DATABASE xxx IS_TEMPLATE = false
and then you will see your database without changing PgAdmin preferences.
I followed the introductory advice from #MwamiTovi but I still did not have an option to create a server as he noted. However, I was able to get my databases to appear by clicking menu option Object -> Register -> Server and type in the information (hostname/address, port) from my associated psql setup.
This was using PG Admin 4.19 on macOS Big Sur.
I want to reduce the number of requirements to get started with my webapp. At the moment you need to run a "create database, create user, grant all" script before you can start debugging.
I'd like the code to be checked out and run straight away without requiring developers to have to read through lots of documentation and do lots of manual steps.
h2 allows you to specify a connection string and it will create the db if it doesn't already exist.
Is it possible to do that using PostgreSQL?
Or is my only option (to meet the requirements) to configure h2 for dev work and PostgreSQL for production?
A connection in Postgres is always to a particular database, but by default every install will have a postgres DB intended for running maintenance commands. The user will still need to supply some superuser login credentials, but assuming you have those, you can run your "create database, create user, grant all" script automatically when the webapp is first accessed.
For instance, have a generated config file which is ignored in source control; before loading the file, check if it exists; if it doesn't, run the install routine.
You can even load an HTML form allowing the user to provide the superuser credentials, choose a name for the DB, and any other commonly-changed configuration options. If these are all defaulted, the "manual step" is simply to glance that they are correct, and click "OK".
I want to set a default statement_timeout for my access to a postgres database. After configuring my environment variables, I now have it where psql logs me on my preferred database and table. However, while I'm exploring several of tables in it, I'd like to have a statement timeout of around a minute. This can be done simply by typing SET statement_timeout TO '1min'; at the beginning of each session, but this is obnoxious to type every time. I don't have access to the server configuration nor would I want to change it. Ideally I could do something to the effect of alias psql='psql -c "SET statement_timeout TO '1min';"' except the-c` flag of psql doesn't allow interactive input. Are there any nice solutions to this problem, or am I always doomed to set the timeout manually for each interactive session?
You could use your .psqlrc file (if you don't have one in your home directory, create it; if you're on Windows instead of *nix, the file is %APPDATA%\postgresql\psqlrc.conf instead) and set the following command:
set statement_timeout to 60000; commit;
That setting is in milliseconds, so that'll set the timeout to 1 minute. .psqlrc isn't used with -c nor -X invocations of psql, so that should allow you to get your interactive-mode timeout to 1 minute.
You can then execute the following in psql to verify that the configuration has taken effect:
show statement_timeout;
Postgres allows you to set configuration parameters such as statement_timeout on a per-role (user) level.
ALTER ROLE <your-username> SET statement_timeout = '60s';
This change will apply to all new sessions for that user, starting on the next login.
Source: Postgres docs
I am beginner to PostgreSQL.
I want to connect to another database from the query editor of Postgres - like the USE command of MySQL or MS SQL Server.
I found \c databasename by searching the Internet, but its runs only on psql. When I try it from the PostgreSQL query editor I get a syntax error.
I have to change the database by pgscripting. Does anyone know how to do it?
When you get a connection to PostgreSQL it is always to a particular database. To access a different database, you must get a new connection.
Using \c in psql closes the old connection and acquires a new one, using the specified database and/or credentials. You get a whole new back-end process and everything.
You must specify the database to use on connect; if you want to use psql for your script, you can use "\c name_database"
user_name=# CREATE DATABASE testdatabase;
user_name=# \c testdatabase
At this point you might see the following output
You are now connected to database "testdatabase" as user "user_name".
testdatabase=#
Notice how the prompt changes. Cheers, have just been hustling looking for this too, too little information on postgreSQL compared to MySQL and the rest in my view.
In pgAdmin you can also use
SET search_path TO your_db_name;
The basic problem while migrating from MySQL I faced was, I thought of the term database to be same in PostgreSQL also, but it is not. So if we are going to switch the database from our application or pgAdmin, the result would not be as expected.
As in my case, we have separate schemas (Considering PostgreSQL terminology here.) for each customer and separate admin schema. So in application, I have to switch between schemas.
For this, we can use the SET search_path command. This does switch the current schema to the specified schema name for the current session.
example:
SET search_path = different_schema_name;
This changes the current_schema to the specified schema for the session. To change it permanently, we have to make changes in postgresql.conf file.
Use this commad when first connect to psql
=# psql <databaseName> <usernamePostgresql>
set search_path = 'schema name here'
while connecting to the postgres, you have to opt for default database to connect. If you have nothing, you can use 'postgres' as default.
You can use dbeaver to connect to postgres. UI is good
PgAdmin 4, GUI Tool: Switching between databases
In the PgAdmin Browser on the left hand side, right click on the database you are willing to switch to.
Select a QueryTool from the drop down menu (or any other option that you need, I will stick with the QueryTool for now).
You will see the QueryTool in the PgAdmin window, and on top you will see the active database and the role name.
Now you can write queries against the chosen database.
You can open multiple QueryTools for multiple database, and work with them as you do with your graphical text editor.
In order to be sure that you are querying the proper database, issue the following query:
SELECT session_user, current_database();