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Opened 7 years ago

Last modified 4 years ago

#1504 new defect

get_last_id() causing an error and sequence question

Reported by: brian@… Owned by: codeFiend
Priority: normal Component: MantisImportScript
Severity: critical Keywords: currval, seqence
Cc: Trac Release: 0.10

Description

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?

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Change History (1)

comment:1 Changed 4 years ago by scott

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

diff:
+++ /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]

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