Getting started on core development

[Shannon Weyrick]

Hi everyone, I'm interested in exploring the core server and I'd like
to work on an entry level issue. I have no particular itch to scratch,
so I've picked SERVER-3518: "Bitwise query operators" as a starting
point to get my feet wet. If any devs have a better suggestion, I'm
open to it.

First question is syntax: can/should this use the existing $bit, as an
operator? Should there be new operators ($bitAnd, $bitOr?), or should
$and, $or be adapted to support bitwise?

Any other comments on implementation (or suggestions for an
alternative issue), would be appreciated.

Thanks!
Shannon

[Eliot Horowitz]

Probably $bitAnd and $bitOr
Lots of little caveats on this though.
Especially with query optimizer, etc...

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[Shannon Weyrick]

Thanks Eliot. I've got a (probably naive) implementation done at
https://github.com/weyrick/mongo/compare/server-3518

Can you elaborate or point me in the direction of where to investigate
the caveats? If they are similar to an existing operator, I could
examine that.

Shannon

[Dwight Merriman]

i think he mainly means how should the query optimizer handle it intelligently (if there are cases for which that is relevant)

also we should look with any new operator at if there are any nuances or nice things that make sense with the aggregation framework - could be it's orthogonal but i don't know without thinking about it a little

[Dwight Merriman]

and how does it align with any $ names of operators in updates.  even if different n eeds to be a predictable pattern to it all.  $bit there is legacy and perhaps not the right way to go.

any new $operator added will be there for decades so have to be a little 

careful

[Shannon Weyrick]

Yes, I agree it should be consistent. From what I can tell, $bitand,
$bitor and $bit are all defined as update modifier ops. Note that
$bitand and $bitor are spelled all lowercase in update, and I'm not
sure they are actually used.

With that in mind, perhaps $bit in the query would be more consistent
and flexible, at the expense of a little more verbosity in the syntax
(vs. bitAnd, bitOr). Derick on #mongodb mentioned that he was working
on adding a few more bit operations to the $bit update modifier, as
well.

https://github.com/derickr/mongo/compare/bitwise-ops