Spatiotemporal search indexing

Before you start indexing spatiotemporal data, you must decide how to configure the data and where to store the spatiotemporal tables and indexes.

When you start the spatiotemporal indexing process, a subtrack table is created for the time series column in the time series base table. The subtrack table contains trajectories that track where objects move, but also stores information about when objects are stationary or do not have a signal. The subtrack table is indexed and the spatiotemporal search system tables are populated with information about the subtrack table and the time series.

You set the definitions for spatiotemporal data, storage spaces, and extent sizes in the BSON parameters document when you run the STS_SubtrackCreate function. You can set default parameters for the database by running the STS_SetDefaultParameters function.

Definitions for spatiotemporal data

You can configure the data in the subtrack table by setting the following definitions:

  • Trajectories for moving objects: Regulate the size of a trajectory by setting how often to generate readings for a trajectory, the maximum duration of a trajectory, and the maximum area of the bounding box around the trajectory.
  • Stationary objects: Set the minimum length of time and the maximum distance that an object can move and still be considered stationary.
  • No data conditions: Set the minimum length of time for a no data condition.

Storage space

Make sure that you have adequate storage space before you start indexing spatiotemporal data.

You can specify storage spaces and extent sizes for each of the following subtrack objects:
  • The subtrack table, which contains a row for each trajectory, stationary period, and period without a signal for an object.
  • The geometry column from the subtrack table, which contains the trajectories. The geometry column can require large amounts of space. You can fragment the geometry column among multiple storage spaces.
  • The index on the primary keys of the subtrack table
  • The index on the end time of the trajectories in the subtrack table
  • The R-tree index on the trajectories in the geometry column
  • The optional functional index on the instance ID of the time series. This index can speed processing during spatiotemporal search queries.