The functions given below are the ones which a user of PostGIS is likely to need. There are other functions which are required support functions to the PostGIS objects which are not of use to a general user.
Returns the 3-dimensional length of the geometry if it is a linestring or multi-linestring.
Returns the 23-dimensional length of the geometry if it is a linestring or multi-linestring.
Returns the area of the geometry if it is a polygon or multi-polygon.
Returns the 3-dimensional perimeter of the geometry, if it is a polygon or multi-polygon.
Returns the 2-dimensional perimeter of the geometry, if it is a polygon or multi-polygon.
Returns true if any part of A is within the bounding box of B.
The "<&" operator returns true if A's bounding box overlaps or is to the right of B's bounding box.
The "&>" operator returns true if A's bounding box overlaps or is to the left of B's bounding box.
The "<<" operator returns true if A's bounding box is strictly to the right of B's bounding box.
The ">>" operator returns true if A's bounding box is strictly to the left of B's bounding box.
The "~=" operator is the "same as" operator. It tests actual geometric equality of two features. So if A and B are the same feature, vertex-by-vertex, the operator returns true.
The "~" operator returns true of A's bounding box is completely contained by B's bounding box.
The "&&" operator is the "overlaps" operator. If A's bounding boux overlaps B's bounding box the operator returns true.
Returns the number of points in the geometry.
If the geometry is a polygon or multi-polygon returns the number of rings.
Returns the amount of space (in bytes) the geometry takes.
Returns the number of objects stored in the geometry. This is useful for MULTI-geometries and GEOMETRYCOLLECTIONs.
Returns a text summary of the contents of the geometry.
The extent() function is an "aggregate" function in the terminology of PostgreSQL. That means that it operators on lists of data, in the same way the sum() and mean() functions do. For example, "SELECT EXTENT(GEOM) FROM GEOMTABLE" will return a BOX3D giving the maximum extend of all features in the table. Similarly, "SELECT EXTENT(GEOM) FROM GEOMTABLE GROUP BY CATEGORY" will return one extent result for each category.
Translates the geometry to a new location using the numeric parameters as offsets. Ie: translate(geom,X,Y,Z).
Forces the geometries into a "2-dimensional mode" so that all output representations will only have the X and Y coordinates. This is useful for force OGC-compliant output (since OGC only specifies 2-D geometries).
Forces the geometries into a "3-dimensional mode" so that all output representations will have the X, Y and Z coordinates.
Returns the geometry in the OGC "well-known-binary" format, using little-endian encoding. This is useful in binary cursors to pull data out of the database without converting it to a string representation.
Returns the geometry in the OGC "well-known-binary" format, using big-endian encoding. This is useful in binary cursors to pull data out of the database without converting it to a string representation.