Fix another timeout when searching for pipelines

When we consider 'all' pipelines for MRs, we now mean: 1. The last 10,000 commits (unordered). 2. From the last 100 MR versions (newest first). This seems to fix the MRs that time out on GitLab.com.

Fix another timeout when searching for pipelines
ec73ecb0 · Sean McGivern · 65faebb9 · ec73ecb0 · ec73ecb0
Commit ec73ecb0 authored Nov 10, 2017 by Sean McGivern
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merge_request.rb app/models/merge_request.rb +13 -1

fix-502-mrs-with-lots-of-versions.yml changelogs/unreleased/fix-502-mrs-with-lots-of-versions.yml +6 -0

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--- a/app/models/merge_request.rb
+++ b/app/models/merge_request.rb
@@ -865,7 +865,19 @@ class MergeRequest < ActiveRecord::Base
  #
  def all_commit_shas
    if persisted?
-      column_shas = MergeRequestDiffCommit.where(merge_request_diff: merge_request_diffs).limit(10_000).pluck('sha')
+      # MySQL doesn't support LIMIT in a subquery.
+      diffs_relation =
+        if Gitlab::Database.postgresql?
+          merge_request_diffs.order(id: :desc).limit(100)
+        else
+          merge_request_diffs
+        end
+
+      column_shas = MergeRequestDiffCommit
+                      .where(merge_request_diff: diffs_relation)
+                      .limit(10_000)
+                      .pluck('sha')
+
      serialised_shas = merge_request_diffs.where.not(st_commits: nil).flat_map(&:commit_shas)

      (column_shas + serialised_shas).uniq

--- a/changelogs/unreleased/fix-502-mrs-with-lots-of-versions.yml
+++ b/changelogs/unreleased/fix-502-mrs-with-lots-of-versions.yml
+---
+title: Ensure merge requests with lots of version don't time out when searching for
+  pipelines
+merge_request:
+author:
+type: performance