The NOvA Database Interface allows one to set "tolerances" on specific columns, such that data for a channel are only written to the database if a column is out of tolerance with the "latest" entry for that channel. Tolerances allow one to minimize the size of a table and speed up queries.

Note that only absolute differences are compared, relative differences are not supported. If no column tolerances are set (eg, table->SetTolerance("column_name",value);), then the followingdefaults are used when writing to the web server:
  • the default tolerance for "double" column types is 1.e-10
  • the default tolerance for "float" column types is 1.e-5
  • the default tolerance for integer types is 0
  • strings must always exactly match