Archive records

Data Archive stores archive events as data records. Data records are either primary records or overflow records. Each point in the PI point database has one primary record allocated in every archive file. Primary records are stored at the very beginning of the archive file. When the primary record for a point fills up, the data for that event goes to an overflow record in the archive file. Overflow records start at the end of the archive file and are filled backwards. Each record is one kilobyte.

A point can have as many overflow records as needed. Points that receive events at a slow rate might never need to allocate an overflow record, whereas points that receive events at a fast rate might need to allocate many overflow records. Data Archive uses index records to keep track of multiple overflow data records for a point.