Massimo,
I tried opening a base url from IE when it had crashed in a session in
Chrome and got no response, so assume it is indeed web2py that crashed.
This was with a field which says ondelete='NO ACTION'. Can we not infer
from the fact pyodbc raised an Exception that was caught by web2py that
control did indeed return to web2py, or is that not correct?
Some info:
web2py™ Version 2.5.1-stable+timestamp.2013.06.06.15.39.19
Traceback (most recent call last):
File "/home/mdipierro/make_web2py/web2py/gluon/restricted.py", line 212,
in restricted
File
"N:/IT/Dev/Code/HubForms/web2py/applications/HubForms/models/7_models_boots_database.py",
line 104, in <module>
File "/home/mdipierro/make_web2py/web2py/gluon/dal.py", line 7788, in
define_table
File "/home/mdipierro/make_web2py/web2py/gluon/dal.py", line 7825, in
lazy_define_table
File "/home/mdipierro/make_web2py/web2py/gluon/dal.py", line 991, in
create_table
File "/home/mdipierro/make_web2py/web2py/gluon/dal.py", line 1094, in
migrate_table
File "/home/mdipierro/make_web2py/web2py/gluon/dal.py", line 1784, in
execute
File "/home/mdipierro/make_web2py/web2py/gluon/dal.py", line 1778, in
log_execute
ProgrammingError: ('42000', "[42000] [Microsoft][ODBC SQL Server
Driver][SQL Server]The object 'boots_project_rfi_testing__constraint' is
dependent on column 'testing'. (5074) (SQLExecDirectW); [42000]
[Microsoft][ODBC SQL Server Driver][SQL Server]ALTER TABLE DROP COLUMN
testing failed because one or more objects access this column. (4922)")
On Wed, Aug 7, 2013 at 9:29 AM, Massimo Di Pierro <
massimo.dipie...@gmail.com> wrote:
> Could this be a pyodbc issue? Are you sure web2py hangs or only this one
> session hangs? You can try from two separate browsers. It is possible
> pyodbc does not return (because for example a circular reference is on
> delete cascade) and web2py keeps the session blocked. All requests from
> this user/session are queued.
>
>
> On Tuesday, 6 August 2013 20:02:51 UTC-5, Andrew Buchan wrote:
>>
>> We have the same (similar) issue using mssql on Windows: when we get a
>> pyodbc.ProgrammingError typically relating to a foreign key, we have to
>> restart web2py.
>>
>> This is particularly frustrating problem as these errors happen every
>> time you rename/delete a column with a foreign key.
>>
>> E.g. create a field that references another table:
>> .....
>> Field('a_field', db.another_table, ondelete='CASCADE'),
>> ....
>> Then remove/rename ;a_field', and you get "ALTER TABLE DROP COLUMN
>> a_field failed because one or more objects access this column."
>>
>> This causes web2py to hang, so we have to go into management studio,
>> delete the constraint, and restart web2py because it has become
>> unresponsive.
>>
>> I think that, aside from resolving why web2py hangs, we could also
>> improve migration so that it deletes any constraints automatically when we
>> drop a column.
>>
>> While we're at it, web2py could check a column actually exists before
>> calling a DROP statement. It frequently happens that things do get out of
>> synch with fake migrates and manually modifying the table etc, and for a
>> DROP statement to be called on a column that has been removed. There is
>> really no benefit in web2py failing if the column to delete isn't found.
>>
>> I thought I'd reply to this thread (ps: right thing to do?) and see if
>> anyone had any suggestions/info before I go raising as bugs/features, or
>> attempting to produce a patch...
>>
>>
>>
>> --
>
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