Transitioning Low Earth Orbit Satellite Archive Data from Informix (Geodetic DataBlade) to PostgreSQL (PostGIS)

Presentation | Presented

  • Churngwei Chu, NASA/SSAI

The NASA Atmospheric Science Data Center (ASDC) archives approximately 2 petabytes of data from instruments on board satellites and science process systems. Currently, ASDC is using the Informix Geodetic DataBlade on a SGI server to store geospatial metadata extracted from the data files. Informix also provides a search capability on the data files to the ASDC web interface.

To reduce cost and constraints of proprietary hardware and software, 2.7 million metadata records have been transferred and tested to a Postgres/PostGIS database on a Linux server. In order to convert the metadata from Informix into PostGIS, we developed an algorithm that splits a geometry (a polygon, a bounding box or a line string) straddling the anti-meridian (+/-180 longitude) into smaller geometries. The algorithm also determines the inclusiveness of the resulting polygons.

We compared results of spatial queries from both databases. The differences of returned results are acceptable for our production system. In one of our best cases, a query in a bounding box search of over 1 million spatial records, Informix and PosgreSQL returned the same results.

In the presentation, we will talk about (1) an introduction of our data holdings, (2) the algorithms used to convert GIS data from Informix to PostGIS, (3) our sql query formulation, and (4) the comparison of returned results from both databases.

Supporting Files