[pgrouting-dev] Non-scheduled Routing algorithm

Kishore Kumar justjkk at gmail.com
Mon Jun 13 13:28:32 EDT 2011


I am facing the following issues in the prototype code[1]:

1. As I am internally calling Dijkstra function and the Dijkstra
implementation assumes that vertex id and edge id are integers but
according to GTFS, stop id and route id can be text also. This can be
solved by:
 a. Generating a new table that maps Auto-generated integers to Stop
 b. Modifying Dijkstra implementation to accept vertex id of type text

2. Since the non-scheduling algorithm is not directly doing any lower
level calculations, I implemented the prototype using PL/pgSQL
language. Is rewriting the same logic in c is required and does it
provide any significant performance boost? According to a post in
pgsql-performance list[2], "I wouldn't expect the queries called by
the pl/pgsql function to be much faster if called through SPI from C
instead.". Hence, my current thought is to give real-life data as
input and check for performance problems and if performance is bad,
write the code in c.

Thanks & Regards,
J Kishore kumar.

[1] - https://github.com/pgRouting/pgrouting/blob/gsoc-multimodal/extra/transit/sql/nonscheduled.sql
[2] - http://archives.postgresql.org/pgsql-performance/2010-05/msg00199.php

On Sun, Jun 12, 2011 at 1:30 PM, Anton Patrushev
<anton.patrushev at georepublic.de> wrote:
> Hi Kishore,
> Ah, now I got it. Well, here in Russia some bus routes also don't have
> fixed schedule and are regulated by number of buses/trips. Thus I
> think the idea makes sense.
> Anton.
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