BSI Range-Encoding: schema support for range frames

[travisturner]

We need a way to specify that a frame should contain range-encoded, integer values (as opposed to equality-encoded bitmaps achieved with SetBit()), and a way to define a schema (list of fields) for the range frame.

Modify the create frame HTTP endpoint:

/index/i/frame/f" -d '{"options":{"rangeEnabled": true}, "fields": [{"name": "age", "type": "int", "min": 1, "max": 120}, {"name": "salary", "type": "int", "min": 10000, "max": 1000000}]}}'

The above command should create a frame with a schema containing two fields: age and salary. Because the rangeEncoded option is provided and set to true, this frame is considered a range frame and as such the following options must be forced to:

• inverseEnabled = false
• cacheType = "none" (this may need to be set to "lru" since we don't currently support "none". that is tracked in implement frame cache type "None" #399)
• cacheSize = 0

The schema needs to be in memory, available to all nodes in the cluster as part of the frame struct. It also needs to be stored on disk in data-dir/index/frame/.schema.

One thing to note about this schema is that it effectively needs to maintain the mapping of fields to rows. So in our example above, rows would be assigned like below:

rowID	represents
0	age: not-null
1	age: component 1
2	age: component 2
3	age: component 3
4	age: component 4
5	age: component 5
6	age: component 6
7	age: component 7
8	salary: not-null
9	salary: component 1
10	salary: component 2
11	salary: component 3
12	salary: component 4
13	salary: component 5
14	salary: component 6
15	salary: component 7
16	salary: component 8
17	salary: component 9
18	salary: component 10
19	salary: component 11
20	salary: component 12
21	salary: component 13
22	salary: component 14
23	salary: component 15
24	salary: component 16
25	salary: component 17
26	salary: component 18
26	salary: component 19
27	salary: component 20

Additionally, we need to maintain the offset of the range. In our salary example, the offset is 10,000 (the min value). By doing this, we can support ranges that don't necessarily start at 0. In theory, we could also support ranges that contain negative numbers.