[pgrouting-users] What is the architecture of pgRouting and how can
I make it work faster?
martinchlee at gmail.com
Wed Aug 3 08:03:19 EDT 2011
[Small note: The author of this question is familiar with PostGIS, but is
not familiar with C language]
I have a 'ways' table in PostGIS consisting of about 90,000 ways. When I do
a pgRouting shortest path query it takes about 2,5 seconds to get the
I was pretty unsatisfied with it (I would like it to be about 1 second for
my imagined user) so I tried to do a 'select * from ways' query in psql with
\timing enabled. It took 3 seconds to respond. When I did 'select name,
length, x1, y1, x2, y2 from ways' (that is all needed to build a graph in my
opinion) it took even more - 4 seconds to respond.
Based on that, I assume that pgRouting's SQL queries are somehow optimized.
1. Is it possible to improve the speed of pgRouting queries?
2. How is the actual shortest path calculation done? Is it anything like the
- Load the whole ways/edges table into memory with one 'select * from ways';
- Build a graph from that;
- Apply a C-based shortest path algorithm to the graph;
- Return a result into psql server?
Can any of these steps be improved anyhow?
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