Project: Persist content graph in MySQL

[larsyencken]

Problem

• During baking, we currently construct a just-in-time content graph, which is expensive due to parsing
• During grapher chart edits, we also have to search for chart references in posts, which is expensive

Proposed solution

Materialise the relationships between charts and articles or other pieces of content in MySQL for fast querying. We should also be able to add SDG references and explorer references here.

Alternative solutions

Not so clear. Persisting to redis has been suggested, baking to static files has been suggested.

Scope

• [ ] #1194
• [ ] #1353
• [ ] #1466

Context

• #1448 (similar concerns of surfacing back-references)