#28451: Change in Oracle sequence name truncation causes regression when 
updating
existing database
-------------------------------------+-------------------------------------
     Reporter:  Kevin Grinberg       |                    Owner:  Kevin
                                     |  Grinberg
         Type:  Bug                  |                   Status:  assigned
    Component:  Database layer       |                  Version:  1.11
  (models, ORM)                      |
     Severity:  Release blocker      |               Resolution:
     Keywords:  oracle               |             Triage Stage:  Accepted
    Has patch:  1                    |      Needs documentation:  0
  Needs tests:  0                    |  Patch needs improvement:  0
Easy pickings:  0                    |                    UI/UX:  0
-------------------------------------+-------------------------------------

Comment (by Tim Graham):

 We'll put the upgrade script here:
 {{{#!python
 from django.db import connection
 from django.db.backends.utils import strip_quotes, truncate_name

 for seq in connection.introspection.sequence_list():
     name_length = 27
     table, column = seq['table'], seq['column']
     if len(table) >= name_length:
         with connection.cursor() as cursor:
             # 1.11.[1-4] format
             old_sq_name = truncate_name('%s_SQ' % strip_quotes(table),
 name_length).upper()
             # pre-1.11, 1.11.5+
             new_sq_name = '%s_SQ' % truncate_name(strip_quotes(table),
 name_length).upper()
             cursor.execute('SELECT sequence_name FROM user_sequences WHERE
 sequence_name=%s', [old_sq_name])
             row = cursor.fetchone()
             if row:
                 cursor.execute('RENAME %s TO %s' % (old_sq_name,
 new_sq_name))
                 args = {
                     'new_tr_name': '%s_TR' %
 truncate_name(strip_quotes(table), name_length).upper(),
                     'tbl_name': table.upper(),
                     'sq_name': new_sq_name,
                     'col_name': column.upper(),
                 }
                 old_tr_name = truncate_name('%s_TR' % strip_quotes(table),
 name_length).upper()
                 cursor.execute('DROP TRIGGER %s' % old_tr_name)
                 trigger_sql = """
                     CREATE OR REPLACE TRIGGER "%(new_tr_name)s"
                     BEFORE INSERT ON %(tbl_name)s
                     FOR EACH ROW
                     WHEN (new.%(col_name)s IS NULL)
                         BEGIN
                             SELECT "%(sq_name)s".nextval
                             INTO :new.%(col_name)s FROM dual;
                         END;
                 /""" % args
                 cursor.execute(trigger_sql)
 }}}

-- 
Ticket URL: <https://code.djangoproject.com/ticket/28451#comment:8>
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