Add Sleeping as a postgres til.

README.md

@@ -150,6 +150,7 @@ smart people at [Hashrocket](http://hashrocket.com/).
 - [Restarting Sequences When Truncating Tables](postgres/restarting-sequences-when-truncating-tables.md)
 - [Send A Command To psql](postgres/send-a-command-to-psql.md)
 - [Set Inclusion With hstore](postgres/set-inclusion-with-hstore.md)
+- [Sleeping](postgres/sleeping.md)
 - [Special Math Operators](postgres/special-math-operators.md)
 - [String Contains Another String](postgres/string-contains-another-string.md)
 - [Temporarily Disable Triggers](postgres/temporarily-disable-triggers.md)

postgres/sleeping.md

@@ -0,0 +1,32 @@
+# Sleeping
+
+Generally you want your SQL statements to run against your database as
+quickly as possible. For those times when you are doing some sort of
+debugging or just want your queries to look very computationally expensive,
+PostgreSQL offers the `pg_sleep` function.
+
+To sleep for 5 seconds, try the following:
+
+```sql
+> select now(); select pg_sleep(5); select now();
+              now
+-------------------------------
+ 2016-01-08 16:30:21.251081-06
+(1 row)
+
+Time: 0.274 ms
+ pg_sleep
+----------
+
+(1 row)
+
+Time: 5001.459 ms
+              now
+-------------------------------
+ 2016-01-08 16:30:26.252953-06
+(1 row)
+
+Time: 0.260 ms
+```
+
+As you'll notice, the `pg_sleep` statement took about 5 seconds.