Optimizing queries

We already used some techniques to speed up queries, although we have a lot more possibilities in tuning queries for faster results. To get the most out of our database, let's see how queries work. First of all, in RDBMS jargon, tables, views, and other similar data structures are called relations. Relation data is stored in files consisting of static-sized blocks (pages). In PostgreSQL, each page takes 8 KB of disk space by default. These pages contain rows (also called tuples). A page can hold multiple tuples, but a tuple cannot span multiple pages. These tuples can be stored quite randomly through different pages; therefore, PostgreSQL has to scan through every page if we do not optimize the given relation. One of the optimization methods is using indexes on columns just like the geometry columns, other data types can be also indexed using the appropriate...