On Wednesday, April 22, 2015 at 2:46:19 PM UTC+1, Michael Bayer wrote: > > > > I carefully re-read your first email, and now I see, that you are trying > to write *TO* the database, yes? And you're comparing the speed of > writing *TO* to the speed of reading *FROM*? > > Unfortunately, selecting data from some tables compared to inserting > data in those tables are two completely different activities. It is > not at all surprising to see a large difference in speed.
Of course. I do not expect that reading from will be as fast as writing to the database. However, 6 minutes to write 11MBs of data is ridiculous, because this is the time it takes even when: 1) there are no text columns (so the nvarchjar(max) issue I mentioned and I saw in other cases cannot apply) 2) there are only floating-point numbers 3) there are no primary keys, no indices and no constraints of any kind I trust you'll concur it's hard to justify such a long time to transfer such a small table even in the examples above. I am not a DBA, but I cannot think of other reasons that would cause such terrible speeds. Any thoughts would be more than welcome! Maybe the to_sql method is committing to the database after inserting every single row and this slows things down? Even so, 6 minutes for 11MBs means 31KB per second. My internet connection in the '90s was faster than that :) I have also been very surprised by the lack of info on the net. Either I am the only one using the to_sql method, or I am the only one who finds it so slow! > > -- You received this message because you are subscribed to the Google Groups "sqlalchemy" group. To unsubscribe from this group and stop receiving emails from it, send an email to [email protected]. To post to this group, send email to [email protected]. Visit this group at http://groups.google.com/group/sqlalchemy. For more options, visit https://groups.google.com/d/optout.
