Avoid triggering N+1 on index page

[luizkowalski]

I noticed a couple of N+1, namely:

• recent_occurrence is being computed but never used
• occurrences.size is not being computed, triggers N+1

To test it, I created a couple of exceptions locally

Queries before:

web        |   SolidErrors::Error Load (2.0ms)  SELECT "solid_errors".*, MAX("solid_errors_occurrences"."created_at") AS recent_occurrence FROM "solid_errors" INNER JOIN "solid_errors_occurrences" ON "solid_errors_occurrences"."error_id" = "solid_errors"."id" WHERE "solid_errors"."resolved_at" IS NULL GROUP BY "solid_errors"."id" ORDER BY "recent_occurrence" DESC
web        |   SolidErrors::Occurrence Count (0.6ms)  SELECT COUNT(*) FROM "solid_errors_occurrences" WHERE "solid_errors_occurrences"."error_id" = $1  [["error_id", 4]]
web        |   SolidErrors::Occurrence Maximum (0.2ms)  SELECT MAX("solid_errors_occurrences"."created_at") FROM "solid_errors_occurrences" WHERE "solid_errors_occurrences"."error_id" = $1  [["error_id", 4]]
web        |   SolidErrors::Occurrence Count (0.2ms)  SELECT COUNT(*) FROM "solid_errors_occurrences" WHERE "solid_errors_occurrences"."error_id" = $1  [["error_id", 3]]
web        |   SolidErrors::Occurrence Maximum (0.2ms)  SELECT MAX("solid_errors_occurrences"."created_at") FROM "solid_errors_occurrences" WHERE "solid_errors_occurrences"."error_id" = $1  [["error_id", 3]]
web        |   SolidErrors::Occurrence Count (0.3ms)  SELECT COUNT(*) FROM "solid_errors_occurrences" WHERE "solid_errors_occurrences"."error_id" = $1  [["error_id", 2]]
web        |   SolidErrors::Occurrence Maximum (0.2ms)  SELECT MAX("solid_errors_occurrences"."created_at") FROM "solid_errors_occurrences" WHERE "solid_errors_occurrences"."error_id" = $1  [["error_id", 2]]
web        |   SolidErrors::Occurrence Count (0.3ms)  SELECT COUNT(*) FROM "solid_errors_occurrences" WHERE "solid_errors_occurrences"."error_id" = $1  [["error_id", 1]]
web        |   SolidErrors::Occurrence Maximum (0.1ms)  SELECT MAX("solid_errors_occurrences"."created_at") FROM "solid_errors_occurrences" WHERE "solid_errors_occurrences"."error_id" = $1  [["error_id", 1]]

after:

web        |   SolidErrors::Error Load (0.5ms)  SELECT "solid_errors".*, MAX("solid_errors_occurrences"."created_at") AS recent_occurrence, COUNT("solid_errors_occurrences"."id") AS occurrences_count FROM "solid_errors" INNER JOIN "solid_errors_occurrences" ON "solid_errors_occurrences"."error_id" = "solid_errors"."id" WHERE "solid_errors"."resolved_at" IS NULL GROUP BY "solid_errors"."id" ORDER BY "recent_occurrence" DESC

[fractaledmind]

Great catch. And great PR. Thank you