-- Ported from the SQLite migration of the same number.
-- What a request went through, beside what it cost: which replica answered,
-- how long it queued in admission, and how long the first token took. Without
-- them "why was my request slow" had no answer — the queue time went out in a
-- response header and nowhere else.
--
-- request_id is the id the client sent or the gateway made, echoed in the
-- X-Request-Id header and the access log, so one request can be followed from
-- the client's error to the replica that served it.
ALTER TABLE usage ADD COLUMN request_id TEXT NOT NULL DEFAULT '';
ALTER TABLE usage ADD COLUMN replica TEXT NOT NULL DEFAULT '';
ALTER TABLE usage ADD COLUMN queue_ms BIGINT NOT NULL DEFAULT 0;
ALTER TABLE usage ADD COLUMN ttft_ms BIGINT NOT NULL DEFAULT 0;
CREATE INDEX usage_by_request ON usage(request_id) WHERE request_id <> '';