Merge branch 'remove-mr-diff-serialised-columns' into 'master'

Remove serialised diff and commit columns

Closes #39533

See merge request gitlab-org/gitlab-ce!15582

2 files changed, 49 insertions, 2 deletions

diff --git a/db/migrate/20171121135738_clean_up_from_merge_request_diffs_and_commits.rb b/db/migrate/20171121135738_clean_up_from_merge_request_diffs_and_commits.rb
new file mode 100644
index 00000000000..30cf08b29fc
--- /dev/null
+++ b/db/migrate/20171121135738_clean_up_from_merge_request_diffs_and_commits.rb
@@ -0,0 +1,36 @@
+class CleanUpFromMergeRequestDiffsAndCommits < ActiveRecord::Migration
+  include Gitlab::Database::MigrationHelpers
+
+  DOWNTIME = false
+
+  class MergeRequestDiff < ActiveRecord::Base
+    self.table_name = 'merge_request_diffs'
+
+    include ::EachBatch
+  end
+
+  disable_ddl_transaction!
+
+  def up
+    Gitlab::BackgroundMigration.steal('DeserializeMergeRequestDiffsAndCommits')
+
+    # The literal '--- []\n' value is created by the import process and treated
+    # as null by the application, so we can ignore those - even if we were
+    # migrating, it wouldn't create any rows.
+    literal_prefix = Gitlab::Database.postgresql? ? 'E' : ''
+    non_empty = "
+      (st_commits IS NOT NULL AND st_commits != #{literal_prefix}'--- []\n')
+      OR
+      (st_diffs IS NOT NULL AND st_diffs != #{literal_prefix}'--- []\n')
+    ".squish
+
+    MergeRequestDiff.where(non_empty).each_batch(of: 500) do |relation, index|
+      range = relation.pluck('MIN(id)', 'MAX(id)').first
+
+      Gitlab::BackgroundMigration::DeserializeMergeRequestDiffsAndCommits.new.perform(*range)
+    end
+  end
+
+  def down
+  end
+end
diff --git a/db/migrate/limits_to_mysql.rb b/db/migrate/limits_to_mysql.rb
index 5cd9f3198e3..8f8d8f27410 100644
--- a/db/migrate/limits_to_mysql.rb
+++ b/db/migrate/limits_to_mysql.rb
@@ -3,8 +3,19 @@ class LimitsToMysql < ActiveRecord::Migration
   def up
     return unless ActiveRecord::Base.configurations[Rails.env]['adapter'] =~ /^mysql/
 
-    change_column :merge_request_diffs, :st_commits, :text, limit: 2147483647
-    change_column :merge_request_diffs, :st_diffs, :text, limit: 2147483647
+    # These columns were removed in 10.3, but this is called from two places:
+    # 1. A migration run after they were added, but before they were removed.
+    # 2. A rake task which can be run at any time.
+    #
+    # Because of item 2, we need these checks.
+    if column_exists?(:merge_request_diffs, :st_commits)
+      change_column :merge_request_diffs, :st_commits, :text, limit: 2147483647
+    end
+
+    if column_exists?(:merge_request_diffs, :st_diffs)
+      change_column :merge_request_diffs, :st_diffs, :text, limit: 2147483647
+    end
+
     change_column :snippets, :content, :text, limit: 2147483647
     change_column :notes, :st_diff, :text, limit: 2147483647
   end