Hello Sean, and everybody That's a very interesting and very important theme: "the new record version will only include the updated fields -- not a full copy of the row"
Do you know where I can find a document, web-page, book or video that explains that? If it has images or graphics, much better. Thanks in advance. Greetings. Walter. On Wed, Sep 16, 2015 at 11:40 AM, 'Leyne, Sean' s...@broadviewsoftware.com [firebird-support] <firebird-support@yahoogroups.com> wrote: > > > > > They will generate a comparable amount of garbage, but I think updating > the > > existing records is better than delete + insert, especially if there are > also > > foreign key references to those records. > > I don't think so. > > Unless you are updating every column in the row, the UPDATE will generate > a smaller disk footprint, as the new record version will only include the > updated fields -- not a full copy of the row. > > Then there is the impact on index structures that Vlad has pointed out. > > > From a performance point of view, it would be *much faster*, if you are > able to: > - disable all indexes for the target table, > - delete all rows, > - import new rows and > - reactivate all indexes for the target table > > This would likely require that you have near-exclusive access/use of the > target table. > > > Sean > > >
