Make Question chains easily extractible from BigQuery Event Store

[thclark]

Feature request

Use Case

We want to be able to extract the sequence of all events that were triggered throughout the process of a grandparent question being executed.

Current db

Proposed Solution

This means we have to maintain a linked list so that a grandchild's events can be associated with a grandparent's questions.

Defining terms

• Originator: refers to the ultimate service or question which triggered the entire tree of questions (and the corresponding sequence of events from each). Synonymous with "ultimate ancestor/parent".

Implementation

• If each event has a parent_question_uuid and a question_uuid then we have a linked list that we can traverse
• We probably should also require an originator_question_uuid (for subscription purposes and for eliminating the need to recurse queries to resolve the linked list in some query scenarios).
• Rename the current originator column to parent
• Make a new column called originator to record the originator service
• Update get_events function
• Consider updating to ordering by datetime for events (keep the order column for now, we may require it later). This is to allow proper ordering of all events in a question chain.
• Update cloud function
• Redeploy cloud function where needed
• Update and redeploy bigquery table where needed
• Test with example service
• Write test of question chaining
• Update documentation
• Test with existing service