Detect loops when going through page tree structure

Sometimes, the ancestors table gets out of synch and that can generate infinite loops when trying to generate the breadcrumbs or generating a page tree. This can lead to OutOfMemory and StackOverflow errors affecting the stability of Confluence.

We should be able to detect these loops and point the user to rebuild the ancestors table (or even rebuild it automatically).

Workaround #1 (if only ancestors table is corrupted)

If you are facing this kind of problems try Rebuilding the Ancestor Table.

Workaround #2 (if both content and ancestors table are corrupted)

• Disable tree macro (if eill make instance unusable in few minutes if enabled and loop exist)
• Find loop in db using

  SELECT *
  FROM content as parent
  LEFT JOIN content AS child
  ON child.parentid = parent.contentid
  WHERE parent.parentid = child.contentid
  

  query

• Fix parent<->child relation
• Rebuild the Ancestor Table
• Enable tree macro