Inline task_states for better performance

src/task-stream.js

@@ -12,38 +12,33 @@ const pipe = require("@promistream/pipe");
 
 const createMutationAPIWrapper = require("./mutation-api/wrapper");
 
+// FIXME: Revert inlining of task_states once switched to PostgreSQL 12+, which can do this automatically using NOT MATERIALIZED
 let query = `
 	WITH
 		dependency_tasks AS (
 			SELECT * FROM
 				json_to_recordset(:dependencyTaskDefinitions) AS x(task text, task_version text)
 		),
-		task_states AS (
+		matching_items AS (
 			SELECT
-				*,
+				DISTINCT ON (items.id)
+				items.*,
+				results.updated_at AS result_date,
+				results.task_version,
 				(
-					is_successful = TRUE
+					results.is_successful = TRUE
 					AND (
-						expires_at < NOW()
+						results.expires_at < NOW()
-						OR is_invalidated = TRUE
+						OR results.is_invalidated = TRUE
 					)
 				) AS is_candidate
-			FROM task_results
-		),
-		matching_items AS (
-			SELECT
-				DISTINCT ON (items.id)
-				items.*,
-				states.updated_at AS result_date,
-				states.is_candidate,
-				states.task_version
 			FROM items
 				INNER JOIN tags
 					ON tags.item_id = items.id
 					AND tags.name = ANY(:tags)
-				LEFT JOIN task_states AS states
+				LEFT JOIN task_results AS results
-					ON states.item_id = items.id
+					ON results.item_id = items.id
-					AND states.task = :task
+					AND results.task = :task
 				WHERE
 					NOT EXISTS (
 						SELECT FROM tasks_in_progress AS pr WHERE pr.item_id = items.id
@@ -65,15 +60,21 @@ let query = `
 		WHERE
 			NOT EXISTS (
 				SELECT
-					task_states.*
+					results.*
 				FROM dependency_tasks
-					LEFT JOIN task_states
+					LEFT JOIN task_results AS results
-						ON dependency_tasks.task = task_states.task
+						ON dependency_tasks.task = results.task
-						AND dependency_tasks.task_version = task_states.task_version
+						AND dependency_tasks.task_version = results.task_version
-						AND task_states.item_id = candidates.id
+						AND results.item_id = candidates.id
 				WHERE
-					task_states.is_candidate IS NULL
+					results.is_successful IS NULL
-					OR task_states.is_candidate = TRUE
+					OR (
+						results.is_successful = TRUE
+						AND (
+							results.expires_at < NOW()
+							OR results.is_invalidated = TRUE
+						)
+					)
 			)
 	) LIMIT :resultLimit;
 `;