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by balfirevic 2135 days ago
Didn't NHibernate have the cartesian product problem solved in a neat way by having various fetch strategies?

You could specify to eagerly load some collections and have NHibernate issue additional select statement to load the children, producing maximum of 2-3 queries (depending on the eager-loading depth) but avoiding both N+1 problem and cartesian row explosion problem.
1 comments
tehlike 2135 days ago
yes, that's the common method, but you still end up issuing multiple network calls. The problem wit issuing select statements to load the children is you have to wait on the first query (root) to finish so you can issue others which adds to the network latency (usually low, but it also depends). It's still not as good as having materialized viewmodels on server where you can issue a single query to get everything you need. The disadvantage is the storage cost, though.
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balfirevic 2135 days ago
I went and looked at the docs to refresh my memory - there was also a subquery fetch strategy where you didn't have to wait for the root entity to load, but that comes at the expense of searching through data twice - which might or might not be worth it, depending on how complicated the query is.

I do wish relational databases (PostgreSQL and SQL Server specifically, since I work with those) had better support for automatically updated real-time materialized views.

Anyway, thanks for working on NHibernate - I miss some of it's configurability and advanced capabilities.

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jacques_chester 2135 days ago
> I do wish relational databases (PostgreSQL and SQL Server specifically, since I work with those) had better support for automatically updated real-time materialized views.

I've been keeping an eye on these folks: https://materialize.io/

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tehlike 2135 days ago
Automatically updated materialized views are something I really want too.

Take a look at ravendb, it might be a good thing to try on next smallish project that you can move to a later one :)

Postgres has a nice advantage of supporting json, so in theory you could have embedded documents as materialized views and whatnot, but it's hard to make it play nice with orms.

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