Change path-name convention shredder uses to be same as needed by filtering (no need to de-shred)

[tatu-at-datastax]

Originally super-shredder path names were thought to be needed to allow "de-shredding" -- re-building of the source document from shredded paths. This is why path to value '5' in:

{ "array" : [ 5 ] }

would become array.[0], escaped so that path is never ambiguous, even if property name contained . (allowed in later Mongo versions) or opening bracket (likewise legal).

But Mongo filtering clauses use simpler, potentially ambiguous notation: array.0.

Although we could of course convert from array.0 into array.[0] it makes more sense to simplify shredded paths because:

1. There is no need to "de-shred" (we store the full document)
2. Avoiding conversion is not only more efficient but also removes possible error modes.

[maheshrajamani]

@tatu-at-datastax Are we going to store duplicate for arrays, in both array_equals and query_*_values?

[tatu-at-datastax]

@maheshrajamani this would not change any of that but yes, contents of arrays are duplicated by Shredder (in array_equals, array_contains and then in one of query_xxx_values).

[maheshrajamani]

Question to explore is can SAI index search of wild card for map key, if so we may not need the array_contains.
Like query_xxx_values['array.*] = 5
@amorton Can we check if this is a possibility?

[tatu-at-datastax]

@maheshrajamani That would be interesting, although could be problematic with deeper nesting as this would match anything with same prefix.

[tatu-at-datastax]

@maheshrajamani I think #92 is now ready: I added test that shows that basic dotted notation now works as expected for filtering:

              {
                "find": {
                  "filter" : {"array.0" : {"$eq" : "value1"}}
                }

and ditto for sub-docs, and nesting to arbitrary levels.

Handling of dotted notation is trickier for update operations and projections but filtering is easy at least.

[amorton]

Question to explore is can SAI index search of wild card for map key, if so we may not need the array_contains.
Like query_xxx_values['array.*] = 5
@amorton Can we check if this is a possibility?

@maheshrajamani It would not be possible, maybe something to add later if / when we create a full JSON type in C*