I do call the query for each neighbour node to find which one is better in building my path.
I think I will try the first way you mentioned. I also found some references using BTREE indexes:
CREATE INDEX nodes_tags_btree_historic_idx on nodes USING BTREE ((tags ? 'historic'));
CREATE INDEX nodes_tags_btree_tourist_idx on nodes USING BTREE ((tags ? 'tourist));
Do you think this could make a difference?
On Mon, Jul 8, 2013 at 1:27 PM, Richard Huxton <dev@archonet.com> wrote:
On 08/07/13 10:20, Radu-Stefan Zugravu wrote:
Any improvement is welcomed. The overall performance of the application is not very good. It takes about 200 seconds to compute a path for not so far star and end points.
So you have to call this query 1000 times with different start and end points?
> I want to improve this query as much as I can.
There's only two ways I can see to get this much below 20ms. This will only work if you want a very restricted range of tags.
Drop the tag index and create multiple geometry indexes instead:
CREATE INDEX node_geo_tourist_idx <index details> WHERE tags ? 'tourist'; CREATE INDEX node_geo_tourist_idx <index details> WHERE tags ? 'history'; etc.
This will only work if you have a literal WHERE clause that checks the tag. It should be fast though.
The second way would be to delete all the nodes that aren't tagged tourist or history. That assumes you are never interested in them of course.
How exactly should I post the explain without the index? Do I have to drop all created indexes for the tags column? It takes some time to create them back.
