The commit 9f4dcea30135d1e36d1c452d631fc8b8743b3995 introduces frozen
chunks. Checking whether a chunk is frozen or not has been done so far
in the query planner. If it is not possible to determine which chunks
are affected by a query in the planner (e.g., due to a cast in the WHERE
condition), all chunks are checked. This leads (1) to an increased
planning time and (2) to the situation that a single frozen chunk could
reject queries, even if the frozen chunk is not addressed by the query.
380464df9b