[web2py:13864] Re: Performance question

Fri, 19 Dec 2008 06:11:21 -0800

The fewer commits, the faster the process.  Also, with one commit, you are less likely to have mixed up data (what happens if two items get committed and then power goes out? 5000 items?)

One situation that you might want to put commit in the loop is if you're using a db table as a log or history.  The point is that the data needs to be in there as soon as it can and if the server goes down, the last entries are the most critical.  Also note that the data records for a log don't relate to another table for anything critical.

-tim

SergeyPo wrote: 
In case when I need to run many updates to database in long cycle,
what is preferred for speed - to have one db.commit() at the end or
commit() after every db update?

E.g.

for i in range(100000):
    db(db.details.id==i).update(**dict([(destination_field, i)]))
    db.commit()

or

for i in range(100000):
    db(db.details.id==i).update(**dict([(destination_field, i)]))
db.commit()



(this is an example only, of course condition db.details.id==i is
dumb).

  

-- 
Timothy Farrell <[email protected]>
Computer Guy
Statewide General Insurance Agency (www.swgen.com)

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