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I think ToroDB is super cool, and I wish your project the best of luck! You can't go wrong building something on PostgreSQL. :) That said, PostgreSQL FDW is NO
by buffyoda 11y ago
I think ToroDB is super cool, and I wish your project the best of luck! You can't go wrong building something on PostgreSQL. :)
That said, PostgreSQL FDW is NOT a great option for MongoDB analytics. Not only is the data model so different that you lose the ability to answer many types of questions, but Multicorn supports only basic pushdown (conjunctions of simple relational operators on original columns).
What this means is that analytics via PostgreSQL via FDW via Multicorn via MongoDB suffers from (a) very poor expressive power, and (b) ridiculously slow performance, since nearly any type of query will require at least one full table scan on all the source tables (in some cases, especially with arrays, many more full table scans may be required for a single query!).
Better off just using ToroDB. Am I right? :)
- ahachete 11y agoThank you, John De Goes. I definitely agree. While PostgreSQL FDWs are a great way of extending Postgres, I don't see they are a good fit for this use case. Not only there are a lot of pushdowns not supported (although that is in the process of being improved), but more importantly, as you mentioned, this connector is going to impose a lot of full table scans for even the simplest queries. I'm dying to benchmark this connector against ToroDB. But unfortunately, the MongoDB proprietary license agreement explicitly forbids any kind of benchmark. I guess they have reasons to do so ;))))))) I cannot be objective saying that you should better of using ToroDB, but I definitely think so. I also want to congratulate you. I think Quasar and SlamData have gone very far, and I'd encourage you to keep on pushing it. While this connector may or may not adversely affect SlamData, there's always room for differentiation and improvement. Good luck!