Re: How to properly index hstore tags column to faster search for keys

On 07/07/13 08:28, Radu-Stefan Zugravu wrote:

Each node has a geometry column called geom and a hstore column
called tags. I need to extract nodes along a line that have certain
keys in the tags column. To do that I use the following query:

SELECT id, tags
FROM nodes
WHERE ST_DWithin(nodes.geom, ST_MakeLine('{$geom1}', '{$geom2}'), 0.001)
AND tags ? '{$type}';

CREATE  INDEX  nodes_tags_idx ON nodes USING GIN(tags);

After creating the index I searched again for nodes using the same first
query but there is no change in performance.

How can I properly use GIN and GIST to index tags column so I can faster
search for nodes that have a certain key in tags column?

Your index definition looks OK. Try showing the output of EXPLAIN ANALYSE for your query - that way we'll see if the index is being used. You can always paste explain output to: http://explain.depesz.com/ if it's too long for the email.

--
  Richard Huxton
  Archonet Ltd