ST_EstimatedExtent
Name
ST_EstimatedExtent — Returns the estimated extent of a spatial table.
Synopsis
box2d
ST_EstimatedExtent
(
text
schema_name
, text
table_name
, text
geocolumn_name
, boolean
parent_only
)
;
box2d
ST_EstimatedExtent
(
text
schema_name
, text
table_name
, text
geocolumn_name
)
;
box2d
ST_EstimatedExtent
(
text
table_name
, text
geocolumn_name
)
;
Description
Returns the estimated extent of a spatial table as a box2d . The current schema is used if not specified. The estimated extent is taken from the geometry column's statistics. This is usually much faster than computing the exact extent of the table using ST_Extent or ST_3DExtent .
The default behavior is to also use statistics collected from child tables (tables
with INHERITS) if available. If
parent_only
is set to TRUE, only
statistics for the given table are used and child tables are ignored.
For PostgreSQL >= 8.0.0 statistics are gathered by VACUUM
ANALYZE and the result extent will be about 95% of the actual one.
For PostgreSQL < 8.0.0 statistics are gathered by running
update_geometry_stats()
and the result extent is exact.
In the absence of statistics (empty table or no ANALYZE called) this function returns NULL. Prior to version 1.5.4 an exception was thrown instead. |
Availability: 1.0.0
Changed: 2.1.0. Up to 2.0.x this was called ST_Estimated_Extent.
This method supports Circular Strings and Curves.