[pgrouting-users] RAM usage and pgrouting performance

Stephen V. Mather svm at clevelandmetroparks.com
Fri Dec 21 06:42:02 PST 2012

Hi Tao,
     I have been thinking about doing something similar.  Did you ever resolve this?


  Stephen V. Mather
GIS Manager
(216) 635-3243 (Work)

From: pgrouting-users-bounces at lists.osgeo.org [pgrouting-users-bounces at lists.osgeo.org] on behalf of Tao Romera Martinez [taoromera at gmail.com]
Sent: Thursday, October 11, 2012 12:26 AM
To: pgRouting users mailing list
Subject: [pgrouting-users] RAM usage and pgrouting performance

Dear all,

I have tried to put the table containing the road network as well as
all the indices related in the RAM, but have not appreciated the
slightest difference in performance when running shortest_dijkstra.
Am I doing something wrong? Has anyone tried to do the same with the
same results?

I was expecting a big speed improvement, since most of the execution
time of shortest_dijkstra goes in fetching the road data from the
table, located in the hard disk.
The way I proceeded to move the table and its indices to the RAM was
to mount a directory of the file system into the RAM and then change
the tablespaces to this directory:

* Create directory and mount
mkdir /DB_data/ram_space
sudo mount -t tmpfs -o size=3000M tmpfs /DB_data/ram_space

* Move tablespaces
CREATE TABLESPACE ram_space LOCATION '/DB_data/ram_space';
ALTER TABLE my_table SET TABLESPACE ram_space;
ALTER INDEX my_index SET TABLESPACE ram_space;

Thanks for any feedback,

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