[postgis-tickets] [PostGIS] #3598: "&&" missing

PostGIS trac at osgeo.org
Tue Jul 12 03:59:59 PDT 2016


#3598: "&&" missing
---------------------------+---------------------------
 Reporter:  jidanni        |      Owner:  robe
     Type:  defect         |     Status:  new
 Priority:  medium         |  Milestone:  PostGIS 2.2.3
Component:  documentation  |    Version:  2.2.x
 Keywords:                 |
---------------------------+---------------------------
 In file:///usr/share/doc/postgis-doc/postgis.html#idm2251
 we see:
 ----
 ''We can avoid this by using the && operator to reduce the number of
 distance calculations required:''

 {{{
 SELECT the_geom
 FROM geom_table
 WHERE ST_DWithin(the_geom,  ST_MakeEnvelope(90900, 190900, 100100,
 200100,312), 100)
 }}}
 ''This query selects the same geometries, but it does it in a more
 efficient way. Assuming there is a GiST index on the_geom, the query
 planner will recognize that it can use the index to reduce the number of
 rows before calculating the result of the ST_distance() function. Notice
 that the ST_MakeEnvelope geometry which is used in the && operation is a
 200 unit square box centered on the original point - this is our "query
 box". The && operator uses the index to quickly reduce the result set
 down to only those geometries which have bounding boxes that overlap the
 "query box". Assuming that our query box is much smaller than the
 extents of the entire geometry table, this will drastically reduce the
 number of distance calculations that need to be done.''
 ------
 But there is no "&&".

--
Ticket URL: <https://trac.osgeo.org/postgis/ticket/3598>
PostGIS <http://trac.osgeo.org/postgis/>
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