1 files changed, 24 insertions, 1 deletions
diff --git a/lib/gitlab/database/migration_helpers.rb b/lib/gitlab/database/migration_helpers.rb
index fc445ab9483..2ebf4956a03 100644
--- a/lib/gitlab/database/migration_helpers.rb
+++ b/lib/gitlab/database/migration_helpers.rb
@@ -80,7 +80,7 @@ module Gitlab
       # here is based on Rails' foreign_key_name() method, which unfortunately
       # is private so we can't rely on it directly.
       def concurrent_foreign_key_name(table, column)
-        "fk_#{Digest::SHA256.hexdigest("#{table}_#{column}_fk").first(10)}"
+        "fk_#{Digest::SHA256.hexdigest('#{table}_#{column}_fk').first(10)}"
       end
 
       # Long-running migrations may take more than the timeout allowed by
@@ -226,6 +226,29 @@ module Gitlab
           raise error
         end
       end
+
+      # This will replace the first occurance of a string in a column with
+      # the replacement
+      # On postgresql we can use `regexp_replace` for that.
+      # On mysql we find the location of the pattern, and overwrite it
+      # with the replacement
+      def replace_sql(column, pattern, replacement)
+        quoted_pattern = Arel::Nodes::Quoted.new(pattern.to_s)
+        quoted_replacement = Arel::Nodes::Quoted.new(replacement.to_s)
+
+        if Database.mysql?
+          locate = Arel::Nodes::NamedFunction.
+            new('locate', [quoted_pattern, column])
+          insert_in_place = Arel::Nodes::NamedFunction.
+            new('insert', [column, locate, pattern.size, quoted_replacement])
+
+          Arel::Nodes::SqlLiteral.new(insert_in_place.to_sql)
+        else
+          replace = Arel::Nodes::NamedFunction.
+            new("regexp_replace", [column, quoted_pattern, quoted_replacement])
+          Arel::Nodes::SqlLiteral.new(replace.to_sql)
+        end
+      end
     end
   end
 end