v2.9.0

Database queries can select only the columns they need, and pooled
connections survive a database restart.

New features

• CrudDB.db_select and Pagination.execute accept a columns argument to
  select only some columns rather than every column of the table. Large
  columns a query does not use are no longer read, and computed expressions
  can be selected alongside table columns
  (database tutorial,
  #120).

Improvements and fixes

• Pooled database connections are tested when taken from the pool, so the
  connections a server dropped, for instance on a database restart or
  failover, are replaced rather than failing the next query. It is on by
  default and set by the new FLUID_DBPOOL_PRE_PING setting
  (settings,
  #120).