Wyrażenie zgody na otrzymywanie Newslettera Cybertec drogąĮlektroniczną jest dobrowolne i może zostać w każdej chwili bezpłatnie odwołane.Więcej informacji Tak, chcę regularnie otrzymywać wiadomości e-mail o nowych produktach, aktualnych ofertach i Granting consent to receive the Cybertec Newsletter by electronic means is voluntary and can be withdrawn free of charge at any time.įurther information can be found in the privacy policy. Yes, I would like to receive information about new products, current offers and news about PostgreSQL via e-mail on a regular basis. Granting consent to receive the CYBERTEC Newsletter by electronic means is voluntary and can be withdrawn free of charge at any time.įurther information can be found in the privacy policy. Weitere Informationen finden Sie in der Datenschutzerklärung. Ich kann diese Zustimmung jederzeit widerrufen. Ja, ich möchte regelmäßig Informationen über neue Produkte, aktuelle Angebote und Neuigkeiten rund ums Thema PostgreSQL per E-Mail erhalten. In order to receive regular updates on important changes in PostgreSQL, subscribe to our newsletter, or follow us on Twitter, Facebook, or LinkedIn. If you are interested in security in general, I would like to recommend “ PostgreSQL TDE” which is a more secure version of PostgreSQL capable of encrypting data on disk. No additional joins are needed to resolve the ID. The trick is mostly the “regrole” data type which allows us to cast an object ID directly to a username so that we can read it more easily. The query shows a list of all roles and how they are nested. Member::regrole || ' -> ' || roleid::regrole AS path Nesting can be infinitely deep, which is why it is necessary to write a recursion, see below: In PostgreSQL, roles / users can be nested. Resolving users and role membership in PostgreSQL Making the system catalog more readable requires a bit of joining, as you will see in the next section. Therefore I have excluded those, because we are only interested in users we have created on our own. In PostgreSQL, all object ids below 16384 are reserved for system objects. The following query shows what my system table contains: It is a simple role / member list which contains object ids to identify our users. It basically knows which role is assigned to which other role. The second important system table here is pg_auth_members. What is noteworthy here is that each user has an internal number (= object id) which identifies the role. Pg_authid contains a list of all roles, as well as some additional information (can log in, is superuser yes / no, etc.). Before we take a look at the final query, it makes sense to check out the system catalog and understand how data is stored. The goal is now to figure out how roles are nested and which role is assigned to which other role. We can now assign roles to other roles (= users), using simple GRANT statements: Behind the scenes, roles and users are all the same. However, if you want a role to be able to log in, you can simply mark it as login. The main difference is that a role is always NOLOGIN while a “user” is LOGIN. The important thing to note here is that “users” and “roles” are basically the same thing. To show how users can be analyzed, we first create a couple of users and roles: Learn how to retrieve information on roles and role membership in PostgreSQL. The following blog post explains how this can be done. However, without a graphical user interface, it is usually a bit tricky to figure out which role is assigned to whom. It allows you to define users (= roles), groups and so on. Using this method we will select the fields we want directly from the pg_user table.PostgreSQL provides a highly sophisticated and powerful security and permission system. There is another way to achieve the same result using SQL. Note that this may be different on your computer. We get an output username and user_attribute with a user named postgres who has the attribute "superuser". Line 9: Lastly, we order the result in ascending order. Line 8: We'll fetch all the results from the pg_user table which gives us access to information about database users. Line 7: We commit this transaction using the END keyword. Line 4: We print out the "superuser" using CAST here because we have to perform a conversion between two data types. Line 3: The usesuper is a boolean type for a "superuser", so what we are saying here is that if the user is a "superuser", perform the operations on lines 4 and 6. Line 2: We introduced the CASE expression, which is the same as the if/else statement in most programming languages. Line 1: We select the usename using an alias username.
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