The following bug has been logged online:
Bug reference: 2664
Logged by: Yoshihisa Nakano
Email address: nakano(dot)yosihisa(at)jp(dot)fujitsu(dot)com
PostgreSQL version: All
Operating system: All
Description: date_trunc('quarter', ...)
Details:
'quarter' is not mentioned in the doc as valid fields for date_trunc().