[postgis-tickets] [PostGIS] #3011: ST_EstimatedExtent return a incorrect extent value

[PostGIS]

#3011: ST_EstimatedExtent return a incorrect extent value
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 Reporter:  rockyc              |       Owner:  pramsey
     Type:  defect              |      Status:  new    
 Priority:  medium              |   Milestone:         
Component:  postgis             |     Version:  2.1.x  
 Keywords:  ST_EstimatedExtent  |  
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Comment(by rockyc):

 Replying to [comment:3 pramsey]:
 > The estimate is based on a sample. Changing the rows changes which
 subset gets picked for the sample, getting a smaller box is not
 unreasonable.

 You means, its results is only based on a sample, and can be changed
 dramatically dependent on the picked sample.

 If I understand correctly, does it mean, sometimes, the return box is
 smaller than the value return from ST_Extent, and sometimes is larger, and
 also, the difference between ST_EstimatedExtent and ST_Extent can be a big
 value, right?

 If it is true, do you have some guidance on when,where and how to use
 ST_EstimatedExtent.

 Thanks

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Ticket URL: <http://trac.osgeo.org/postgis/ticket/3011#comment:4>
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