in 0.4 there is atomic update, e.g. update set a=expression syntax is something like table.update( values=dict-of-name-expression ).execute( **bindings-if-any) expressions is whatever sa sql expression
On Tuesday 11 September 2007 09:25:46 Hermann Himmelbauer wrote: > Hi, > I need to safely increase a numeric value via SQLAlchemy: > I have a table that has a column with numeric data. For increasing > the value, I need to read the data, add some value and store it, so > it would look like that: > > - select myvalue from mytable > - myvalue += 123 > - update mytable and set myvalue to 123 > > However, problems arise when two of this operations are done > simultaneously, e.g. operation A and B: > > A - select > B - select > A - increase > B - increase > A - update > B - update > > In this case, operation A is overwritten by B. > > One viable solution would be to make the operation atomic, by e.g. > locking the database row. Is this possible with SQLAlchemy? If yes, > how? > > Or is there a better way? > > Best Regards, > Hermann --~--~---------~--~----~------------~-------~--~----~ You received this message because you are subscribed to the Google Groups "sqlalchemy" group. To post to this group, send email to sqlalchemy@googlegroups.com To unsubscribe from this group, send email to [EMAIL PROTECTED] For more options, visit this group at http://groups.google.com/group/sqlalchemy?hl=en -~----------~----~----~----~------~----~------~--~---
