[PostGIS] #5734: Wrong ST_EstimatedExtent result for geography column

PostGIS trac at osgeo.org
Wed May 22 04:26:33 PDT 2024


#5734: Wrong ST_EstimatedExtent result for geography column
----------------------+---------------------------
  Reporter:  strk     |      Owner:  pramsey
      Type:  defect   |     Status:  new
  Priority:  medium   |  Milestone:  PostGIS 3.4.3
 Component:  postgis  |    Version:  3.4.x
Resolution:           |   Keywords:
----------------------+---------------------------
Comment (by strk):

 The estimate itself seems off:
 {{{
 DEBUG:  analyzing "public.qgis_issue_30294"
 DEBUG:  "qgis_issue_30294": scanned 1 of 1 pages, containing 2 live rows
 and 0 dead rows; 2 rows in sample, 2 estimated total rows
 DEBUG:  [gserialized_estimate.c:compute_gserialized_stats_mode:1419]
 compute_gserialized_stats called
 DEBUG:  [gserialized_estimate.c:compute_gserialized_stats_mode:1420]  #
 sample_rows: 2
 DEBUG:  [gserialized_estimate.c:compute_gserialized_stats_mode:1421]
 estimate of total_rows: 2
 DEBUG:  [gserialized_estimate.c:nd_box_from_gbox:602]
 GBOX((0.96984631,-0.17101008,0),(0.96984637,-0.17101006,0))
 DEBUG:  [gserialized_estimate.c:nd_box_from_gbox:602]
 GBOX((0.81379765,0.29619813,0),(0.81379771,0.29619816,0))
 }}}

 I don't see how the above matches the actual boxes:
 {{{
 strk=# select g::geometry::box2d from qgis_issue_30294;
           g
 ----------------------
  BOX(-10 -10,-10 -10)
  BOX(20 30,20 30)
 (2 rows)
 }}}
-- 
Ticket URL: <https://trac.osgeo.org/postgis/ticket/5734#comment:3>
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