we're all consenting programmers here are we not? I expect it to do what I mean it to do :)
-Thadeus On Wed, Dec 9, 2009 at 4:50 AM, Maciek Sykulski <[email protected]> wrote: > > > On Dec 8, 10:09 pm, mdipierro <[email protected]> wrote: >> You are right. I think this line was introduced to fix a problem and >> created another. The "SET FOREIGN_KEY_CHECKS=0" should be executed >> only when dropping a table in MySQL. Do you agree? > > Hi Massimo, > > I'm not sure. With SET FOREIGN_KEY_CHECKS=1 MySQL won't allow DROP > TABLE to be executed when there are other tables referencing it, which > might be a very good thing because database remains consistent. > In an ideal world user should alter referencing tables and remove all > referencing columns before delete/truncate is performed. Oracle has > CASCADE CONSTRAINTS which causes all relevant constraints to be > dropped. MySQL drop table CASCADE is not doing anything in later > versions. > On the other hand, TRUNCATE TABLE might be an opposite problem - it > does delete all rows in a table and also all others from other tables > referencing it. This means that a whole database may be purged by > db.table.truncate() not well thought through (ON DELETE CASCADE is the > default setting for all foreign key references in web2py, isn't it?). > > The FOREIGN_KEY_CHECKS should be 1 for most of operations. > When comes to delete, truncate - I'm not sure how to weight on that. > It depends on general policy of web2py - how user-friendly, dummy- > proof, do-what-i-want-no-matter-what it is. > > Maciek > > >> On Dec 8, 2:47 pm, Maciek Sykulski <[email protected]> wrote: >> >> > Hi, >> >> > We noticed that in our MySQL database ON DELETE CASCADE is not working >> > when a row is deleted by web2py controller. >> > It is working ok when I run SQL delete from mysql console. >> > Because of that, it is possible to get database into inconsistent >> > state with web2py >> >> > When looking into this problem I noticed self._execute('SET >> > FOREIGN_KEY_CHECKS=0;') in web2py source: >> >> > web2py$ grep -n -A 2 -B 10 -e "FOREIGN_KEY_CHECKS" -R * >> > gluon/sql.py-870- self._pool_connection(lambda : >> > MySQLdb.Connection( >> > gluon/sql.py-871- db=db, >> > gluon/sql.py-872- user=user, >> > gluon/sql.py-873- passwd=passwd, >> > gluon/sql.py-874- host=host, >> > gluon/sql.py-875- port=int(port), >> > gluon/sql.py-876- charset=charset, >> > gluon/sql.py-877- )) >> > gluon/sql.py-878- self._cursor = self._connection.cursor() >> > gluon/sql.py-879- self._execute = lambda *a, **b: >> > self._cursor.execute(*a, **b) >> > gluon/sql.py:880: self._execute('SET >> > FOREIGN_KEY_CHECKS=0;') >> > gluon/sql.py-881- self._execute("SET >> > sql_mode='NO_BACKSLASH_ESCAPES';") >> > gluon/sql.py-882- elif not is_jdbc and self._uri[:11] == >> > 'postgres://': >> >> > What is the rationale for self._execute('SET FOREIGN_KEY_CHECKS=0;') >> > there? >> > I'd like to have my database consistent and ON DELETE CASCADE working >> > - >> > can I/ should I change it to =1 ? >> >> > I've found a discussion about FOREIGN_KEY_CHECKS in web2py >> > here ...but not sure if it's >> > related.http://markmail.org/message/6472owgwupttlblq >> >> > Regards, >> > Maciek > > -- > > You received this message because you are subscribed to the Google Groups > "web2py-users" group. > To post to this group, send email to [email protected]. > To unsubscribe from this group, send email to > [email protected]. > For more options, visit this group at > http://groups.google.com/group/web2py?hl=en. > > > -- You received this message because you are subscribed to the Google Groups "web2py-users" group. To post to this group, send email to [email protected]. To unsubscribe from this group, send email to [email protected]. For more options, visit this group at http://groups.google.com/group/web2py?hl=en.
