oz · December 19, 2014 15:21 · Dec 19, 2014
diff --git a/upgradepg.md b/upgradepg.md
@@ -0,0 +1,26 @@
+# Brew upgrade...
+
+Run the usual `brew update`, and `brew upgrade` to get the latest 9.4 version of PostgreSQL.
+
+After upgrading PG from 9.3 to 9.4 with brew, the server will not start as is. If you value your database contents, and configuration, `pg_upgrade` is here to migrate those.
+
+Do *not* delete the old binaries at once: do not run `brew cleanup`, because you need 9.3 binaries to migrate.
+
+# Migration
+
+By default, your PG should be in `/usr/local/var/postgres`, but those files are not compatible with the latest 9.4 release.
+
+With that, the upgrade is simple enough:
+
+```shell
+$ mv /usr/local/var/postgres /usr/local/var/postgres93
+$ initdb -D /usr/local/var/postgres
+$ pg_upgrade -b /usr/local/Cellar/postgresql/9.3.5_1/bin -B /usr/local/Cellar/postgresql/9.4.0/bin -d /usr/local/var/postgres93 -D /usr/local/var/postgres
+```
+
+If all goes well, you can start `postgres -D ...`, and cleanup the old stuff:
+
+```shell
+$ rm -fr /usr/local/var/postgres93
+$ brew cleanup
+```