Add Check The Size Of Databases In A Cluster as a Postgres TIL

README.md

@@ -10,7 +10,7 @@ pairing with smart people at Hashrocket.
 
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@@ -806,6 +806,7 @@ If you've learned something here, support my efforts writing daily TILs by
 - [Check If The Local Server Is Running](postgres/check-if-the-local-server-is-running.md)
 - [Check If User Role Exists For Database](postgres/check-if-user-role-exists-for-database.md)
 - [Check Table For Any Oprhaned Records](postgres/check-table-for-any-orphaned-records.md)
+- [Check The Size Of Databases In A Cluster](postgres/check-the-size-of-databases-in-a-cluster.md)
 - [Checking Inequality](postgres/checking-inequality.md)
 - [Checking The Type Of A Value](postgres/checking-the-type-of-a-value.md)
 - [Clear The Screen In psql](postgres/clear-the-screen-in-psql.md)

postgres/check-the-size-of-databases-in-a-cluster.md

@@ -0,0 +1,39 @@
+# Check The Size Of Databases In A Cluster
+
+The `\l` command in `psql` will list all the databases for the server. The
+field surfaced by this meta-command are:
+
+- Name
+- Owner
+- Encoding
+- Locale Provider
+- Collate
+- Ctype
+- ICU Locale
+- ICU Rules
+- Access privileges
+
+If we add a `+`, issuing instead `\l+`, we get three additional fields:
+
+- Size
+- Tablespace
+- Description
+
+The _Size_ column is the human-formatted size of each database.
+
+Another way to do this is with some SQL querying the underlying record keeping
+of the server's database.
+
+```sql
+select
+  db.datname as db_name,
+  pg_size_pretty(pg_database_size(db.datname)) as db_size
+from pg_database db
+order by pg_database_size(db.datname) desc;
+```
+
+Credit to [this StackOverflow
+answer](https://stackoverflow.com/a/18907188/535590) for how to do this with a
+SQL query.
+
+[source](https://www.postgresql.org/docs/current/app-psql.html#APP-PSQL-META-COMMAND-LIST)