PostGIS in Action

Chapter 9. Performance tuning

 

This chapter covers

• Planner basics
• Reading plans
• Common query patterns
• Geometry processing for better performance
• Influencing plans

 

When dealing with several tables at once—especially large ones—tuning queries, tables, and geometries becomes a major consideration. The way you express your queries is also important because the same logic expressed with two different SQL statements can have vastly different performance. The complexity of geometries, memory allocation, and even storage affect performance.

The query planner has many options to choose from, especially when joining tables. The planner can choose certain indexes over others, the order in which it navigates these indexes, and which navigation strategies ...