Diskussion:HSR Texas Geo Database Benchmark: Unterschied zwischen den Versionen

Version vom 15. Januar 2010, 14:34 Uhr

Feel free to discusss 'HSR Texas Spatial Database Benchmark' issues here! Stefan 18:39, 22. Dez. 2009 (CET)

ToDo

• standardise data and input process (circumvent or minimize floating point problem)
• define the variables (@bbox and @point)
  • should we take an average of multiple runs with different values?
• should we vary the queries' result sizes? (see observations below)
• should we vary the shape and alignment of the query window? (see observations below)

Observations

General:

• MS SQL Server representatives report that geography types are 20-30% slower than geometry types.
• About PostGIS 1.5 there was said, that geography types are somewhat faster (see http://blog.cleverelephant.ca/)
• Secondary index optimization makes performance about 50% faster (from: MS SQL Server discussion)
• The number of points of a query window is important for a secondary filter overhead.

Data and queries per se:

• These queries return quite large percent of the data overall (50%-100% for points and polygons)
• The Number of points for a query windows is very small.
• The query windows are "aligned bounding boxes" which may put in favor RTree (e.g. Postgres) or spatial grid (SQL Server) index, depending on a position of the window. If the window is aligned with the grid, performance can be much faster than when it's slightly off.

Discussion Points

Typically the bbox variable is "grid aligned" - What's the impact? Is this typical?

tdb.