Hi, I'd be very careful about calling it bulk_save(), since calling it something with save() very strongly suggests that it calls pre_save or post_save signals.
Best Raphael Am Fri, 14 Sep 2018 07:56:38 -0700 (PDT) schrieb Tim Graham <timogra...@gmail.com>: > > > I wanted to ask about naming of the new method. Currently the > proposed name is "QuerySet.bulk_save()" but I think it's a bit > confusing since it uses QuerySet.update(), not Model.save(). It works > similarly to QuerySet.bulk_update() from > https://github.com/aykut/django-bulk-update but the arguments are a > bit different. > > > Josh's comment on the PR: "Since this only works for instances with > an pk, do you think that bulk_update would be a better name? The > regular save() method can either create or update depending on pk > status which may confuse users here." > > And Tom's reply: "I considered this, but queryset.update() is the > best 'bulk update' method. I didn't want to confuse the two, this is > more about saving multiple model fields with multiple differing > values, gene bulk_save. Open to changing it though." > > > On Tuesday, January 23, 2018 at 7:38:18 AM UTC-5, Neal Todd wrote: > > > > Hi Tom, > > > > That's great, should be a helpful addition to core. Will follow the > > ticket and PR. > > > > Neal > > > > (Apologies - I hadn't spotted that you'd already referenced > > django-bulk-update in your ticket when I left my drive-by comment!) > > > > On Monday, January 22, 2018 at 7:41:11 PM UTC, Tom Forbes wrote: > >> > >> Hey Neal, > >> > >> Thank you very much for pointing that out, I actually found out > >> about this package as I was researching the ticket - I wish I had > >> known about this a couple of years ago as it would have saved me a > >> fair bit of CPU and brain time! > >> > >> I think that module is a good starting point and proves that it’s > >> possible, however I think the implementation can be improved upon > >> if we bring it inside core. I worked on a small PR to add this > >> <https://github.com/django/django/pull/9606/files#diff-5b0dda5eb9a242c15879dc9cd2121379R473> > >> > >> and the implementation was refreshingly simple. It still needs > >> docs, a couple more tests and to fix a strange error with sqlite > >> on Windows, but overall it seems like a lot of gain for a small > >> amount of code. > >> > >> Tom > >> > >> > >> On 22 January 2018 at 15:10:53, Neal Todd (ne...@torchbox.com) > >> wrote: > >> > >> Hi Tom, > >> > >> A built-in bulk save that's more flexible than update would > >> certainly be nice. Just in case you haven't come across it though, > >> there is a package called django-bulk-update: > >> > >> https://github.com/aykut/django-bulk-update > >> > >> I've found it very useful on a number of occassions where update > >> isn't quite enough but the loop-edit-save pattern is too slow to > >> be convenient. > >> > >> Probably some useful things in there when considering the API and > >> approach. > >> > >> Cheers, Neal > >> > >> On Friday, January 19, 2018 at 5:49:48 PM UTC, Tom Forbes wrote: > >>> > >>> Hello all, > >>> > >>> I’d love for some feedback on an idea I’ve been mulling around > >>> lately, namely adding a bulk_save method to Dango. > >>> > >>> A somewhat common pattern for some applications is to loop over a > >>> list of models, set an attribute and call save on them. This > >>> unfortunately can issue a lot of database queries which can be a > >>> significant slowdown. You can work around this by using > >>> ‘.update()’ in some cases, but not all. > >>> > >>> It seems it would be possible to use a CASE statement in SQL to > >>> handle bulk-updating many rows with differing values. For example: > >>> > >>> SomeModel.object.filter(id__in=[1,2]).update( > >>> some_field=Case( > >>> When(id=1, then=Value('Field value for ID=1')), > >>> When(id=2, then=Value('Field value for ID=2')) > >>> ) > >>> ) > >>> > >>> I’ve made a ticket for this here: > >>> https://code.djangoproject.com/ticket/29037 > >>> > >>> I managed to get a 70x performance increase using this technique > >>> on a fairly large table, and it seems it could be applicable to > >>> many projects just like bulk_create. > >>> > >>> The downsides to this is that it can produce very large SQL > >>> statements when updating many rows (I had MySQL complain about a > >>> 10MB statement once), but this can be overcome with batching and > >>> other optimisations (i.e the same values can use WHEN id IN (x, > >>> y, z) rather than 3 individual WHEN statements). > >>> > >>> I’m imagining an API very similar to bulk_create, but spend any > >>> time on a patch I thought I would ask if anyone have any feedback > >>> on this suggestion. Would this be a good addition to Dango? > >>> > >>> > >>> -- > >> You received this message because you are subscribed to the Google > >> Groups "Django developers (Contributions to Django itself)" group. > >> To unsubscribe from this group and stop receiving emails from it, > >> send an email to django-develop...@googlegroups.com. > >> To post to this group, send email to django-d...@googlegroups.com. > >> Visit this group at > >> https://groups.google.com/group/django-developers. To view this > >> discussion on the web visit > >> https://groups.google.com/d/msgid/django-developers/5988d579-7843-4c42-a6f9-1e389c58ece6%40googlegroups.com > >> <https://groups.google.com/d/msgid/django-developers/5988d579-7843-4c42-a6f9-1e389c58ece6%40googlegroups.com?utm_medium=email&utm_source=footer> > >> . > >> For more options, visit https://groups.google.com/d/optout. > >> > >> > -- You received this message because you are subscribed to the Google Groups "Django developers (Contributions to Django itself)" group. To unsubscribe from this group and stop receiving emails from it, send an email to django-developers+unsubscr...@googlegroups.com. To post to this group, send email to django-developers@googlegroups.com. Visit this group at https://groups.google.com/group/django-developers. To view this discussion on the web visit https://groups.google.com/d/msgid/django-developers/20180914173155.41685505%40kvothe. For more options, visit https://groups.google.com/d/optout.
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