Time-series data in JSON

Question

I need to model 1,000,000+ data points in JSON. I am thinking of two ways of doing this:

a) Array of objects:

[{time:123456789,value:1432423},{time:123456790,value:1432424},....]

or

b) Nested arrays

[[123456789,1432423],[123456790,1432424],....]

Naively comparing these two approaches, it feels like the latter is faster because it uses less characters but less descriptive. Is b really faster than a ? Which one would you choose and why ?

Is there a 3rd approach ?

Answer 1

{time:[123456789,123456790,...], value:[1432423,1432424,...]}

why?

1. iterating over a primitive array is faster.
2. comparable to "JSON size" with b) but you will not lose the "column" information

this npm could be of interest: https://github.com/michaelwittig/fliptable

Answer 2

If your time series data models some continuous function, especially over regular time intervals, there could be much more efficient representation with delta compression, even if you are still using JSON:

[
    {time:10001,value:12345},
    {time:10002,value:12354},
    {time:10003,value:12354},
    {time:10010,value:12352}
]

Can be represented as:

[[10001,1,1,7],[12345,9,,-2]]

Which is a 4 times shorter representation.

The original could be reconstructed with:

[{time:a[0][0],value:a[1][0]},{time:a[0][0] + a[0][1]||1, value: a[1][0] + a[1][1]||0 ...