SQLAlchemy

#2527: CircularDependencyError, possible bug in UOW ..?
---------------------------+-----------------------------------------------
      Reporter:  jcigar    |      Owner:  zzzeek
          Type:  defect    |     Status:  new
      Priority:  medium    |  Milestone:
     Component:  orm       |   Severity:  no triage selected yet
    Resolution:            |   Keywords:  unit of work, circular dependency
Progress State:  awaiting  |
  triage                   |
---------------------------+-----------------------------------------------

Comment (by jcigar):

 I digged a little bit more, and it seems that the problem is that
 ''use_alter=True'' *'''must'''* be set on the foreign keys which have
 circular dependencies.

 I don't know if this should be considered as a bug in the autoload
 feature? In other words: Should the autoload feature detects foreign keys
 which have circular dependencies and set ''use_alter=True'' on those?

 So it works with the following:

 {{{
 #!python
     table_content = schema.Table('content', db_meta,
         schema.Column('container_id', types.Integer(),
                   schema.ForeignKey('folder.content_id', use_alter=True,
                                     name='fk_folder')),

         schema.Column('icon_content_id', types.Integer(),
                   schema.ForeignKey('data.content_id', use_alter=True,
                                     name='fk_data')),
         autoload=True,
         extend_existing=True,
         autoload_replace=True,
         autoload_with = db_engine)
 }}}

-- 
Ticket URL: <http://www.sqlalchemy.org/trac/ticket/2527#comment:1>
sqlalchemy <http://www.sqlalchemy.org/>
The Database Toolkit for Python

#2527: CircularDependencyError, possible bug in UOW ..?
---------------------------+-----------------------------------------------
      Reporter:  jcigar    |      Owner:  zzzeek
          Type:  defect    |     Status:  new
      Priority:  medium    |  Milestone:
     Component:  orm       |   Severity:  no triage selected yet
    Resolution:            |   Keywords:  unit of work, circular dependency
Progress State:  awaiting  |
  triage                   |
---------------------------+-----------------------------------------------

Comment (by zzzeek):

 um ok, here's a tip.  **I cannot run a test that relies upon reflection, I
 do not have your database here**.  If the error is just the use_alter for
 the FK, no that's not a bug, it's documented.

 I'm going to make the test run and assuming the cirtuclardep is just your
 FK, this is a "worksforme" (this is why its essential to send along stack
 traces when issues are first reported).

-- 
Ticket URL: <http://www.sqlalchemy.org/trac/ticket/2527#comment:2>
sqlalchemy <http://www.sqlalchemy.org/>
The Database Toolkit for Python

#2527: CircularDependencyError, possible bug in UOW ..?
---------------------------+-----------------------------------------------
      Reporter:  jcigar    |      Owner:  zzzeek
          Type:  defect    |     Status:  closed
      Priority:  medium    |  Milestone:
     Component:  orm       |   Severity:  no triage selected yet
    Resolution:            |   Keywords:  unit of work, circular dependency
  worksforme               |
Progress State:            |
  completed/closed         |
---------------------------+-----------------------------------------------
Changes (by zzzeek):

 * status:  new => closed
 * resolution:   => worksforme
 * status_field:  awaiting triage => completed/closed


Comment:

 sorry, this test names eight tables that aren't defined here so this is
 not a useful test case.   use_alter is required for cycles in foreign
 keys, here's the docs which introduce that from an ORM perspective:
 http://docs.sqlalchemy.org/en/rel_0_7/orm/relationships.html#rows-that-
 point-to-themselves-mutually-dependent-rows

-- 
Ticket URL: <http://www.sqlalchemy.org/trac/ticket/2527#comment:3>
sqlalchemy <http://www.sqlalchemy.org/>
The Database Toolkit for Python

#2527: CircularDependencyError, possible bug in UOW ..?
---------------------------+-----------------------------------------------
      Reporter:  jcigar    |      Owner:  zzzeek
          Type:  defect    |     Status:  closed
      Priority:  medium    |  Milestone:
     Component:  orm       |   Severity:  no triage selected yet
    Resolution:            |   Keywords:  unit of work, circular dependency
  worksforme               |
Progress State:            |
  completed/closed         |
---------------------------+-----------------------------------------------

Comment (by zzzeek):

 I'm just seeing your SQL script, sorry.  But in the future I really need
 succinct test cases that I can run in one step, thanks.

-- 
Ticket URL: <http://www.sqlalchemy.org/trac/ticket/2527#comment:4>
sqlalchemy <http://www.sqlalchemy.org/>
The Database Toolkit for Python

#2527: use a subset of sort tables when we only need to sort on inheritance chains
---------------------------+-----------------------------------------------
      Reporter:  jcigar    |      Owner:  zzzeek
          Type:  defect    |     Status:  reopened
      Priority:  medium    |  Milestone:  0.8.0
     Component:  orm       |   Severity:  major - 1-3 hours
    Resolution:            |   Keywords:  unit of work, circular dependency
Progress State:  in queue  |
---------------------------+-----------------------------------------------
Changes (by zzzeek):

 * status:  closed => reopened
 * severity:  no triage selected yet => major - 1-3 hours
 * milestone:   => 0.8.0
 * resolution:  worksforme =>
 * status_field:  completed/closed => in queue


Comment:

 I see where the use_alter is being required in an unusual place, this can
 be improved.

-- 
Ticket URL: <http://www.sqlalchemy.org/trac/ticket/2527#comment:5>
sqlalchemy <http://www.sqlalchemy.org/>
The Database Toolkit for Python

#2527: use a subset of sort tables when we only need to sort on inheritance chains
---------------------------+-----------------------------------------------
      Reporter:  jcigar    |      Owner:  zzzeek
          Type:  defect    |     Status:  reopened
      Priority:  medium    |  Milestone:  0.8.0
     Component:  orm       |   Severity:  major - 1-3 hours
    Resolution:            |   Keywords:  unit of work, circular dependency
Progress State:  in queue  |
---------------------------+-----------------------------------------------

Comment (by zzzeek):

 here is the test case.

 {{{
 from sqlalchemy import *
 from sqlalchemy.orm import *
 from sqlalchemy.ext.declarative import declarative_base

 Base= declarative_base()

 class A(Base):
     __tablename__ = "a"

     id = Column(Integer, primary_key=True)
     b_id = Column(Integer, ForeignKey('b.id'))

 class B(A):
     __tablename__ = "b"

     id = Column(Integer, ForeignKey('a.id'), primary_key=True)

     __mapper_args__ = {'inherit_condition':id==A.id}

 e = create_engine("sqlite://", echo=True)

 Base.metadata.create_all(e)

 s = Session(e)

 s.add(B())
 s.flush()
 }}}

-- 
Ticket URL: <http://www.sqlalchemy.org/trac/ticket/2527#comment:6>
sqlalchemy <http://www.sqlalchemy.org/>
The Database Toolkit for Python

#2527: use a subset of sort tables when we only need to sort on inheritance chains
---------------------------+-----------------------------------------------
      Reporter:  jcigar    |      Owner:  zzzeek
          Type:  defect    |     Status:  reopened
      Priority:  medium    |  Milestone:  0.8.0
     Component:  orm       |   Severity:  major - 1-3 hours
    Resolution:            |   Keywords:  unit of work, circular dependency
Progress State:  in queue  |
---------------------------+-----------------------------------------------

Comment (by jcigar):

 yep :) I would not have provided a test case that use reflection without
 providing the sql script itselfs .. :) I was unable to reproduce the bug
 with sqlite, that's why I provided my original pgsql script. I'm 99% sure
 that the problem only occur with reflection. I had read the doc about
 mutual dependency, but the question is really if use_alter=True should be
 set by the "reflection engine" automatically (if not, a notice in the doc
 could maybe be useful?)

-- 
Ticket URL: <http://www.sqlalchemy.org/trac/ticket/2527#comment:7>
sqlalchemy <http://www.sqlalchemy.org/>
The Database Toolkit for Python

#2527: use a subset of sort tables when we only need to sort on inheritance chains
---------------------------+-----------------------------------------------
      Reporter:  jcigar    |      Owner:  zzzeek
          Type:  defect    |     Status:  reopened
      Priority:  medium    |  Milestone:  0.8.0
     Component:  orm       |   Severity:  major - 1-3 hours
    Resolution:            |   Keywords:  unit of work, circular dependency
Progress State:  in queue  |
---------------------------+-----------------------------------------------

Comment (by zzzeek):

 the reflection is not strictly necessary, however you'd need to know
 what's going on here to know that, so in this case i can't fault you for
 that (though you can try removing all those extra tables next time).

 I didn't see the sql scripts since I went straight to the test case in the
 email, sorry.

-- 
Ticket URL: <http://www.sqlalchemy.org/trac/ticket/2527#comment:8>
sqlalchemy <http://www.sqlalchemy.org/>
The Database Toolkit for Python

#2527: use a subset of sort tables when we only need to sort on inheritance chains
---------------------------+-----------------------------------------------
      Reporter:  jcigar    |      Owner:  zzzeek
          Type:  defect    |     Status:  closed
      Priority:  medium    |  Milestone:  0.8.0
     Component:  orm       |   Severity:  minor - half an hour
    Resolution:  fixed     |   Keywords:  unit of work, circular dependency
Progress State:            |
  completed/closed         |
---------------------------+-----------------------------------------------
Changes (by zzzeek):

 * status:  reopened => closed
 * resolution:   => fixed
 * severity:  major - 1-3 hours => minor - half an hour
 * status_field:  in queue => completed/closed


Comment:

 this is 0.8 only since it's destabilizing and is in r580ea6c2fbdd .  sorry
 for the noise.

-- 
Ticket URL: <http://www.sqlalchemy.org/trac/ticket/2527#comment:9>
sqlalchemy <http://www.sqlalchemy.org/>
The Database Toolkit for Python