If you are not going to use the native replication mode, you can skip this section.
If you plan to use native replication mode and insert_lock, creating pgpool_catalog.insert_lock table for mutual exclusion is strongly recommended. Without this, insert_lock works so far. However in that case Pgpool-II locks against the insert target table. This behavior is same table lock conflicts with VACUUM, so INSERT processing may be thereby kept waiting for a long time.
$ cd pgpool-II-4.1.2/src/sql $ psql -f insert_lock.sql template1
Executing insert_lock.sql should be performed on every databases accessed via Pgpool-II. You do not need to do this for a database created after the execution of psql -f insert_lock.sql template1, as this template database will be cloned to create new databases.