Use Case 14

Representing Structured Metadata and Data

(msdemlei)

This is probably fairly related to use cases 3, 4, and 9, but I'd like to make this explict.

In many parts of astronomy, there are sequences of complex (in the sense of not plain integers, floats, or strings) objects.

As an example, think of a photometry point, consisting of at least a flux and bandpass, plus possibly errors, all kinds of provenance-related information, etc. These subordinate objects may be complex again (e.g., error matrices) or even sequences of complex objects (e.g., source images in a stacked image).

Such objects occur both in the data (say, in a table row given both V- and I-band data in various apertures and by PSF-fit) and in the metadata (e.g., when the data is a time series and some basic photometry is given on the object observed).

A single row in a table may contain more than one object of this kind (multiple photometries, multiple STC sets, etc). The same goes for a single metadata collection.

As tables may have billions of rows, it'd be great if per-instance overhead of representing (presumably annotating) this kind of structure could be low to neglible.