Methods of timestamping data for storage Timestamping tables

Methods of time-stamping data for storage Time-stamping tables Methods for storing spatio-temporal data Time-stamping rows Time-stamping attributes • From a database standpoint, temporal data can be stored in three ways. • Data can be stored by time-stamping attributes, timestamping rows, or time-stamping tables. • These three methods are described here.

Time-stamping of tables Time-stamp for table Attribute table for 2001 -2 Attribute table for 2002 -3 Attribute table for 2003 -4 • Each table stores attributes for a different time period

Time-stamping of tables • Each table has its own time stamp 1 st June 05 Polygon ID Land owner Exists from Exists until 1 R. Treves Apr 2000 May 2003 1 J. Wright May 2003 Jun 2004 2 J. Wright Apr 2000 Jun 2004 5 th May 05 Polygon ID Land owner Exists from Exists until 1 R. Treves Apr 2000 May 2003 1 J. Wright May 2003 Jun 2004 2 J. Wright Apr 2000 Jun 2004

Time-stamping of rows • Each row has its own time stamp Polygon ID Land owner Exists from Exists until 1 1 R. Treves Apr 2000 May 2003 1 J. Wright May 2003 Jun 2004 2 J. Wright Apr 2000 Jun 2004 2

Time-stamping of attributes • Each attribute has its own time stamp Polygon ID AREA 1 45 2 55 1 2 Attribute Table Polygon ID 1 Land owner R. Treves Exists from Exists until Apr 2000 May 2003 1 J. Wright May 2003 Jun 2004 2 J. Wright Apr 2000 Jun 2004 Each row is one attribute

Time-stamping of attributes • Separate tables can be used for different attributes, such as land ownership and land use. Polygon ID AREA 1 45 2 55 1 2 Time-stamp for attribute Polygon ID 1 Land use Exists from Exists until Agriculture Apr 2000 Feb 2002 1 Forestry Mar 2002 Jun 2004 2 Agriculture Apr 2000 Jun 2004 Table of attributes for land use