get_last_id() causing an error and sequence question

[Aeon]

On 1-May-2007, at 9:09am, brian wrote (Trac issue 1504):

This line was giving me an error.

return self.db().get_last_id(c,'ticket')

psycopg2.ProgrammingError: currval of sequence "ticket_id_seq" is not yet defined in this session

This seems utterly wrong to me since i can select currval('ticket_id_seq') via psql.
It's not used so i commented it out.

On a slightly different note, are the sequences in postgresql set correctly after all tickets, comments, stuff are inserted?

[Aeon]

On 16-Apr-2010, at 11:21am, scott wrote (Trac issue 1504#comment:1):

I ran into this as well.

The problem is that currval of a sequence id is a a session-local value. It cannot be retrieved unless nextval has been called for the current session.

I fixed this by modifying:
/usr/lib/python2.6/dist-packages/trac/db/postgres_backend.py

to call setval, max(id) first to update the sequence value for the session

+++ /usr/lib/python2.6/dist-packages/trac/db/postgres_backend.py
@@ -215,5 +215,6 @@
         return _like_escape_re.sub(r'/\1', text)
 
     def get_last_id(self, cursor, table, column='id'):
+ cursor.execute("SELECT SETVAL('%s_%s_seq', max(%s)) FROM %s" % (table, column,column,table))
         cursor.execute("SELECT CURRVAL('%s_%s_seq')" % (table, column))
         return cursor.fetchone()[0]