Merge pull request #1701 from Kobzol/update-db-instructions

Add instructions on how to remove master/try artifact data

Author: Kobzol

database/queries.md

@@ -1,7 +1,7 @@
 # Useful queries
 This document contains useful queries that should be performed manually in exceptional situations.
 
-## Remove data for an artifact from the DB
+## Remove data for a stable artifact from the DB
 This is important for situations where there is some compilation error for a stable benchmark,
 with a stable release of the compiler. While this should be rare, it happens sometimes e.g. because
 of future incompatibility lints turning into errors.
@@ -19,3 +19,17 @@ WHERE name IN ('1.69.0', '1.70.0') AND
       type = 'release';
 ```
 After executing this query, the server should automatically re-benchmark these artifacts again.
+
+## Remove data for a master/try artifact from the DB
+This is similar to removing a stable artifact, however it also has to be removed from the
+`pull_request_build` table.
+
+```sql
+DELETE FROM artifact
+WHERE name = "<sha>";
+
+DELETE FROM pull_request_build
+WHERE bors_sha = "<sha>";
+```
+After that, the server has to be restarted, or you have to send a GET request to its `/perf/onpush`
+endpoint.