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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 implemen
by davidmathers 17y ago
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.
- kragen 17y agoHaha! 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'.