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A comment on MongoDB vs Redis, a different interpretation of what's wrong with Relational DBs. Parent comment

Re:MongoDB vs Redis, a different interpretation of what's wr... by kragen on Wednesday June 03, 2009 @09:53PM (#640820)
You can't get select, project, or cartesian product out of ismember, union, and intersection. Also, union corresponds to and and intersection corresponds to or, not the other way around as your comment has it.
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Re:MongoDB vs Redis, a different interpretation of what's wr... by davidmathers on Wednesday June 03, 2009 @10:12PM (#640842)
You can't get select, project, or cartesian product out of ismember, union, and intersection.

Sorry, I didn't mention that redis has SADD and SREM for implementing projection. I'm not sure what you mean by select. You're right about product. I think that's what's missing.

Also, union corresponds to and and intersection corresponds to or

That's exactly what I said. We both got it backwards.

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Re:MongoDB vs Redis, a different interpretation of what's wr... by kragen on Thursday June 04, 2009 @07:48AM (#641240)
Haha! You're right.

"Select" is the SPC-algebra operation which gives you the subset of a relation whose tuples satisfy some Boolean condition, e.g. firstname='bob'.

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