Hierarchically organized STAC APIs

[moradology]

In the most recent release of the STAC API specification (i.e. v1.0.0-beta.5), two features have been added which imply a hierarchical representation of of STAC documents within STAC APIs: children and browseable. A recently added draft on stac_fastapi implements these features with an in memory representation of the hierarchy which defines behavior for both of these features.

In this draft, the hierarchy is specified separately from the ingested contents of the database. For instance, the data which defines the Joplin collection and its various related items is supplied via a json file and an environment variable which tells the server where a valid hierarchy definition can be located.

Assuming this structure is sufficient and desiring a more robust implementation which leverages the performance and benefits for implementers of other STAC libraries which might lean on pgstac, it would be great to push this information and associated behaviors down to postgres.

Below are some TODOs in the stac_fastapi draft which are next to functions/behavior which could likely find its home in pgstac

[moradology]

Function to look up catalog from the new catalogs table: https://github.com/stac-utils/stac-fastapi/pull/336/files#diff-1976a4ae1097a62eeb3fcf5486db05da340c8187aa529bb246488e6b5237d9c5R41-R42

[moradology]

Functions for ingesting hierarchy to table of catalogs: https://github.com/stac-utils/stac-fastapi/pull/336/files#diff-1976a4ae1097a62eeb3fcf5486db05da340c8187aa529bb246488e6b5237d9c5R180

[moradology]

Generate partially completed link json in postgres to avoid pulling all data from collections and catalogs: https://github.com/stac-utils/stac-fastapi/pull/336/files#diff-48c3b9c11c264e04cde80885bcab3d58d0a21f0e3e245e52c51e7893ee969ec7R103

[moradology]

Add optional catalog argument to determine which collections should be included in search: https://github.com/stac-utils/stac-fastapi/pull/336/files#diff-48c3b9c11c264e04cde80885bcab3d58d0a21f0e3e245e52c51e7893ee969ec7R310-R311

[moradology]

Add function to return all collection children (or simply all children?) for a given catalog: https://github.com/stac-utils/stac-fastapi/pull/336/files#diff-48c3b9c11c264e04cde80885bcab3d58d0a21f0e3e245e52c51e7893ee969ec7R375-R376