[Zope-DB] Dynamically generate sql-query in ZSQL Method

Ian Bicking ianb at colorstudy.com
Thu Apr 8 12:22:12 EDT 2004

Matthew T. Kromer wrote:
> On Apr 7, 2004, at 6:29 PM, Ian Bicking wrote:
>> Well, in one case I was commiting a credit card transaction after 
>> sending it to the processor, but before rendering the result page, so 
>> that an error in the result page can't keep me from saving the 
>> transaction to the database.  And in general I'm not putting 
>> persistent data into the ZODB, so I don't have to worry about 
>> integrity across the two systems.
>> And Zope won't really retry a transaction, will it?  That's just... 
>> well, way to clever for anyone's good.  Plus I do get actual conflict 
>> errors from the database, which would imply it isn't retrying them.  
>> And with some RDBMS's you can't do that at all, like MySQL.  Do I 
>> really have to worry about rerunning transactions?
> Yes, if you have any doubts write an external method which prints to the 
> console or something... watch it get reexecuted on ConflictErrors.
> ConflictErrors are retried 3 times before the conflict is allowed to 
> pass out in an error page.
> You really do have to worry about re-running transactions.

I had bad dreams last night -- literally -- thinking about what this 
means to all the code I've written or maintained in Zope, and anything 
that involves a side-effect.

Just when you think you've found a pattern of application development in 
Zope that works okay -- even if it's not the Right Way or a 
sophisticated Zope way of managing things -- Zope turns around and 
punches you in the gut.  Damn.

Well, thank's for correcting me, even if you are the bringer of bad news ;)


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