[postgis-users] Nearest line from a point

Jaime Casanova jaime at 2ndquadrant.com
Sat Aug 20 22:07:38 PDT 2011

On Sat, Aug 20, 2011 at 2:58 PM, Stephen Woodbridge
<woodbri at swoodbridge.com> wrote:
> On 8/20/2011 3:34 PM, Jaime Casanova wrote:
>> On Sat, Aug 20, 2011 at 7:36 AM, Charles Galpin<cgalpin at lhsw.com>  wrote:
>>> I assume you mean it takes a long time? The key is to create a buffer
>>> around the point that is as big as you feel necessary to make a
>>> match, and then in your where clause only match lines that intersect
>>> this. That way the index is used to limit the number of
>>> candidates to get the distance for.  Something like
>>> where line&&  st_expand(myPoint, bufferSizeInYourProjectionUnits)
>> st_dwithin() doesn't do this automatically?
>> but i should admit it wasn't useful for me... it still require a seq
>> scan on the whole table
> Have you create a gist (not a btree) index on your geometry column?

Yes, I have... Here was posted my problem
and this is the EXPLAIN ANALYZE using st_dwithin() in the query

the table has a GiST index on the table transmitter_mv

Jaime Casanova         www.2ndQuadrant.com
Professional PostgreSQL: Soporte 24x7 y capacitación

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