Hello
My plugin tried to post some stuff and I've got:
WP_Error Object ( [errors] => Array ( [db_insert_error] => Array ( [0] => Could not insert post into the database ) ) [error_data] => Array ( [db_insert_error] => ERROR: duplicate key value violates unique constraint "mood_posts_pkey" DETAIL: Key ("ID")=(39) already exists. ) )
I have clean wordpress install with imported old posts (tool > import), and I don't specify any id on insert.
Postgres 9.1
http://wordpress.org/extend/plugins/postgresql-for-wordpress/