Improve Conduit performance for custom fields
Summary:
Ref T11404. Depends on D16350.
Currently, custom fields can issue "N+1" queries in some cases, so querying 100 revisions issues 100 extra queries.
This affects all `*.search` endpoints for objects with custom fields, and some older endpoints (notably `differential.query`).
This change bulk loads "normal" custom fields, which gets rid of some of these queries. Instead of loading fields for each object, we build a big list of all fields and load them all at once.
The next change will tackle the remaining inefficient edge queries.
Test Plan:
- Configured a custom field with normal database storage in Differential.
- Ran `differential.query`, looking at custom fields in results for correctness.
- Ran `differential.revision.search`, looking at custom fields in results for correctness.
- In both cases, observed queries drop from `3N` to `2N` (all the "normal" custom field stuff got bulk loaded).
Reviewers: yelirekim, chad
Reviewed By: chad
Maniphest Tasks: T11404
Differential Revision: https://secure.phabricator.com/D16351