Add Truncate All Rows as a postgres til.

README.md

@@ -128,6 +128,7 @@ smart people at [Hashrocket](http://hashrocket.com/).
 - [Temporary Tables](postgres/temporary-tables.md)
 - [Timestamp Functions](postgres/timestamp-functions.md)
 - [Toggling The Pager In PSQL](postgres/toggling-the-pager-in-psql.md)
+- [Truncate All Rows](postgres/truncate-all-rows.md)
 - [Turning Timing On](postgres/turning-timing-on.md)
 - [Types By Category](postgres/types-by-category.md)
 - [Use Argument Indexes](postgres/use-argument-indexes.md)

postgres/truncate-all-rows.md

@@ -0,0 +1,21 @@
+# Truncate All Rows
+
+Given a postgres database, if you want to delete all rows in a table, you
+can use the `DELETE` query without any conditions.
+
+```
+> delete from pokemons;
+DELETE 151
+```
+
+Though `DELETE` can do the job, if you really are deleting all rows to clear
+out a table, you are better off using `TRUNCATE`. A `TRUNCATE` query will be
+faster than a `DELETE` query because it will just delete the rows without
+scanning them as it goes.
+
+```
+> truncate pokemons;
+TRUNCATE TABLE
+```
+
+[source](http://www.postgresql.org/docs/8.2/static/sql-truncate.html)