[postgis-tickets] [PostGIS] #5120: ST_EstimatedExtent returns stats based extent even if index is present

[PostGIS]

#5120: ST_EstimatedExtent returns stats based extent even if index is present
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 Reporter:  strk     |      Owner:  pramsey
     Type:  defect   |     Status:  new
 Priority:  medium   |  Milestone:  PostGIS 3.3.0
Component:  postgis  |    Version:  master
 Keywords:           |
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 When a GiST index is present on a geometry column it makes no sense for
 ST_EstimatedExtent to fallback to stats-based view, if the index based
 bbox is returned as null, because that means the table is empty.

 To reproduce the problem:
   1. Create a spatial table, with an index
   2. Add some rows, ANALYZE (creates stats)
   3. Truncate the table
   4. Run ST_EstimatedExtent for the spatial column

 Note there's NO WAY to clear the stats on a truncated table, to my
 knowledge. The only way to "refresh" the stats would be to re-add some
 rows to it. Instead, in the scenario above, users are left to an
 ST_EstimatedExtent return which is plain bogus, when all the information
 would be available to the function to return an informed NULL (no rows in
 the table, according to index).

 See also #5032 for a possibly misinformed value from index query too.

 I've tested this in 3.3.0dev (master branch) but it's very likely an old
 issue.

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Ticket URL: <https://trac.osgeo.org/postgis/ticket/5120>
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