Returns a binary string that is a linear hash of the geometry.
geometry-expression.ST_LinearHash()
BINARY(32) Returns a binary string that is a linear hash of the geometry.
The spatial index support uses a linear hash for geometries that maps the geometries
in a table into a linear order in a B-Tree index.
The ST_LinearHash method exposes this mapping by returning a binary string that gives the
ordering of the rows in the B-Tree index.
The hash string provides the following property: if geometry
A covers geometry B,
then
A.ST_LinearHash() >= B.ST_LinearHash()
.
The linear hash can be used in an ORDER BY clause. For example, when unloading data from a SELECT statement, ST_LinearHash can be used to generate a data file that matches the clustering of a spatial index.
SQL/MM (ISO/IEC 13249-3: 2006) Vendor extension
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