two Database syncrho

[Ari Lion BR Sp]

Hi to all, 

I am trying to  understand how to use the below feature:

DAL.distributed_transaction_commit(db_a, db_b)

mentined here:

http://www.web2py.com/books/default/chapter/29/06/the-database-abstraction-layer#Distributed-transaction

Does web2py does the synchro work, through DAL?

Thanks!

[Ari Lion BR Sp]

Hi, any?

[Massimo Di Pierro]

Yes. Only on PostgreSQL, MySQL and Firebird. Assuming the feature has not been broken over time, I do not know of anybody who used it.

[Carlos Correia]

Às 06:14 de 01/07/20, Massimo Di Pierro escreveu:

Hi, Massimo,

It seems to be broken :(

I have this piece of code in a controller to test a distributed transaction but it fails with: 
"ValueError: need more than 0 values to unpack".

def index():
    response.flash = T("Hello World")
    db0 = DAL( 'postgres://belmiro:naosei@localhost/ennos__blm_0139' )
    db1 = DAL( 'postgres://belmiro:naosei@localhost/ennos__blm_0143' )
    DAL.distributed_transaction_begin( db0, db1 )
    db0.auth_event.insert( description='test tx 0' )
    db1.auth_event.insert( description='test tx 1' )
    DAL.distributed_transaction_commit( db0, db1 )
    return dict(message=T('Welcome to web2py!'))

Stack trace:

  File ".../web2py/applications/welcome/controllers/default.py", line 12, in index
    DAL.distributed_transaction_begin( db0, db1 )
  File ".../web2py/gluon/packages/dal/pydal/base.py", line 341, in distributed_transaction_begin
    keys = ['%s.%i' % (thread_key, i) for (i, db) in instances]

Best regards,

Carlos Correia
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[Carlos Correia]

Às 13:28 de 04/07/20, Carlos Correia escreveu:

Indeed it has a bug in gluon/packages/dal/pydal/base.py at lines 341 and 342, which should be switched.

341         keys = ['%s.%i' % (thread_key, i) for (i, db) in instances]
342         instances = enumerate(instances)

should be:

341         instances = enumerate(instances)
342         keys = ['%s.%i' % (thread_key, i) for (i, db) in instances]

I switched the lines, tested, and it worked as expected. Shall I open an issue on Github?