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From Ron Cecchini <roncecch...@comcast.net>
Subject Drill + Mongo
Date Thu, 05 Mar 2020 05:28:29 GMT
Hi, guys.

This is actually more of a Mongo question than a Drill-specific question as it also applies
to Presto + Mongo, and the vanilla Mongo shell as well.

I'm asking here, though, because, well, I'm curious, and because you're the database geniuses...

So, I essentially get why a NoSQL database, in general, wouldn't be as performant as a SQL
one at "relational" things.  From what I gather, there are denormalization and optimization
techniques and tricks you can use to speed up a Mongo query and so forth, but my question
is:

Why is it that any Drill/Presto + Mongo CLI or JDBC query against a large collection (100-200
million documents) that includes even a single WHERE clause, or the Mongo equivalent query
made via Mongo shell, basically never returns and has to be killed, whereas the same (Mongo
equivalent) query against the same collection made via *Mongo's* JDBC driver takes only a
second or two?

Is the Mongo JDBC using some indexing that the others aren't?  (But how would that explain
Mongo shell's non-performance...  Why doesn't Mongo shell just make a JDBC call to the db...)

Thank you in advance for educating me.

Ron

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