Interesting - so it will be possible in 1.2 to do more custom relationship loading in a "post load" hook?
Thanks for the feedback! That definitely makes sense - I didn't fully understand all the logic in _emit_lazyload() initially so I wasn't sure what was OK to remove and what wasn't. I made a PR with those changes here: https://github.com/operator/sqlalchemy_bulk_lazy_loader/pull/1. One thing I still don't fully understand is the passive variable. What does passive mean, and is it set per-model or per-relationship? Thanks a lot Mike! On Wednesday, May 3, 2017 at 10:14:03 PM UTC+8, Mike Bayer wrote: > > > Related note, in 1.2 I'm adding a new mechanism for loading things which > is a "post load" hook, that is, a bunch of objects are loaded in a > query, and then afterwards, more loaders can run on a batch of completed > objects. The effect looks similar to how "subqueryload" works right > now, except "subqueryload" fires off within the initial population step > of the objects. The two kinds of loaders using this are the "select IN" > loading, which is like subqueryloading but more or less better in most > ways (also seems you're doing "select IN" here), and "select IN" loading > of subclass attributes on a joined inheritance mapping. > > The hook you have here would be a third kind of hook, a "lazyload that > works across the Session" hook. Definitely something new. I'm not > sure all of the logic that's been copied into _emit_lazyload() really > applies though; the top logic is all related to the specific object that > has triggered the load, like if its pending or not, if it had any query > option set up, the state.load_path, etc. You can't assume any of that > stuff applies to all the other states if you are going across the whole > result. It's probably better, since this is a very different kind of > loader, to make it just load for all the states in the same way without > looking at any of their options or things like that. > > > > On 05/03/2017 08:52 AM, David Chanin wrote: > > Ack, thanks Simon! That is definitely a bug :). I just pushed a fix. > > > > Thanks for the feedback! > > David > > > > On Wednesday, May 3, 2017 at 5:47:54 PM UTC+8, David Chanin wrote: > > > > Hi Everyone, > > > > We just open-sourced a custom lazy loader for SQLAlchemy that does > > bulk lazy loading of relations - essentially a lazy subqueryload. > > The idea is that whenever a relation is lazy-loaded on a model, the > > loader will look for all similar models in the session that haven't > > had that relation populated yet and will issue a single SQL query to > > populate them all in bulk. I'm really curious to hear any feedback > > you may have on this idea / implementation, pitfalls that we're > > overlooking, or ideas for improvement. The repo is at > > https://github.com/operator/sqlalchemy_bulk_lazy_loader > > <https://github.com/operator/sqlalchemy_bulk_lazy_loader>. Hope > it's > > useful to others as well. > > > > Thanks so much! > > > > -- > > SQLAlchemy - > > The Python SQL Toolkit and Object Relational Mapper > > > > http://www.sqlalchemy.org/ > > > > To post example code, please provide an MCVE: Minimal, Complete, and > > Verifiable Example. See http://stackoverflow.com/help/mcve for a full > > description. > > --- > > 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 sqlalchemy+...@googlegroups.com <javascript:> > > <mailto:sqlalchemy+unsubscr...@googlegroups.com <javascript:>>. > > To post to this group, send email to sqlal...@googlegroups.com > <javascript:> > > <mailto:sqlal...@googlegroups.com <javascript:>>. > > Visit this group at https://groups.google.com/group/sqlalchemy. > > For more options, visit https://groups.google.com/d/optout. > -- SQLAlchemy - The Python SQL Toolkit and Object Relational Mapper http://www.sqlalchemy.org/ To post example code, please provide an MCVE: Minimal, Complete, and Verifiable Example. See http://stackoverflow.com/help/mcve for a full description. --- 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 sqlalchemy+unsubscr...@googlegroups.com. To post to this group, send email to sqlalchemy@googlegroups.com. Visit this group at https://groups.google.com/group/sqlalchemy. For more options, visit https://groups.google.com/d/optout.
