chore(postgres): slightly extend knowledge on tools

knowledge base/postgresql/pg_dumpall.md

@@ -3,7 +3,9 @@
 > [!caution]
 > TODO
 
-Intro
+Command-line tool for creating backups of entire PostgreSQL clusters, and/or global objects like roles and
+tablespaces.<br/>
+Consider using [`pg_dump`][pg_dump] to create backups of a single database when nothing else is needed.
 
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 ## Table of contents <!-- omit in toc -->
@@ -14,6 +16,25 @@ Intro
 
 ## TL;DR
 
+It can dump databases in their entirety, or just specific parts of them such as individual tables or schemas.<br/>
+It **can** dump objects like roles, groups, tablespace and others.
+
+It produces sets of SQL statements that can be executed to reproduce the original databases' object definitions and
+table data.
+
+Suitable when:
+
+- The databases' size is **less** than 100 GB.<br/>
+  It tends to start giving issues for bigger databases.
+- One plans to migrate the databases' metadata as well as the table data.
+- There is a relatively large number of tables to migrate.
+
+> [!important]
+> `pg_dumpall` works better when the database is taken offline, but it **does keep the database available** and will
+> **not** prevent users from accessing it.<br/>
+> Even with other users accessing the database during the backup process, `pg_dumpall` will **always** produce
+> consistent results thanks to ACID properties.
+
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 <details>
   <summary>Setup</summary>