Oracle7 Spatial Data Option User's Guide and Reference

Window Functions

The SDO_WINDOW functions are used to create temporary geometric objects to be used in comparisons with stored geometries. You can create query windows with any number of coordinates.

This chapter contains descriptions of the following window functions:

Table 7¯1 Window Functions

Function Description
BUILD_WINDOW

Builds a query window geometric object.

BUILD_WINDOW_FIXED

Builds a query window using fixed-size tiles.

CLEAN_WINDOW

Drops the tables used for a query window.

CREATE_WINDOW_LAYER

Creates the tables needed for a query window layer.

SDO_WINDOW.BUILD_WINDOW

Purpose

This function builds the window for the query and returns an SDO_GID which serves as a handle. The window is tessellated into variable-sized tiles.

Syntax

SDO_WINDOW.BUILD_WINDOW(comp_name, layername, SDO_ETYPE, SDO_NUMTILES, X1, Y1, [...Xn, Yn])

Keywords and Parameters

comp_name

Specifies the name of the user who compiled this package. This user must have appropriate privileges to read and write into the database. Datatype is VARCHAR2.

layername

Specifies the name of the window layer into which the coordinates will be inserted. Datatype is VARCHAR2.

SDO_ETYPE

Specifies the type of geometric element. Datatype is INTEGER, corresponding to the following constants:
1 SDO_GEOM.POINT_TYPE
2 SDO_GEOM.LINESTRING_TYPE
3 SDO_GEOM.POLYGON_TYPE

SDO_NUMTILES

Specifies the number of tiles the window should be tessellated into. Datatype is NUMBER.

X ordinateN,
Y ordinateN

Specifies the X and Y values of a vertex (coordinate pair) in a geometry. Up to 125 pairs may be added in a single call. Datatype is NUMBER.

Returns

This function returns the SDO_GID of the new geometry. Datatype is NUMBER.

Usage Notes

This function inserts the coordinates into the <layername>_SDOGEOM table, tessellates the geometry (creates the index), and returns a unique SDO_GID corresponding to the geometry.

You do not need special privileges to execute this function. However, the user who compiles it does need appropriate privileges to read and write into the database.

Related Topics

SDO_WINDOW.BUILD_WINDOW_FIXED() function

SDO_WINDOW.BUILD_WINDOW_FIXED

Purpose

This function builds the window for the query and returns an SDO_GID which serves as a handle. The window is tessellated into fixed-size tiles.

Syntax

SDO_WINDOW.BUILD_WINDOW_FIXED (comp_name, layername, SDO_ETYPE, SDO_TILESIZE, X1, Y1, [...Xn, Yn])

Keywords and Parameters

comp_name

Specifies the name of the user who compiled this package. This user must have appropriate privileges to read and write into the database. Datatype is VARCHAR2.

layername

Specifies the name of the window layer into which the coordinates will be inserted. Datatype is VARCHAR2.

SDO_ETYPE

Specifies the type of geometric element. Datatype is INTEGER, corresponding to the following constants:
1 SDO_GEOM.POINT_TYPE
2 SDO_GEOM.LINESTRING_TYPE
3 SDO_GEOM.POLYGON_TYPE

SDO_TILESIZE

Specifies a fixed size for the tiles the window will be tessellated into. Datatype is NUMBER.

X ordinateN,
Y ordinateN

Specifies the X and Y values of a vertex (coordinate pair) in a geometry. Up to 125 pairs may be added in a single call. Datatype is NUMBER.

Returns

This function returns the SDO_GID of the new geometry. Datatype is NUMBER.

Usage Notes

Note The syntax and usage of this procedure is likely to change in a future release of Spatial Data Option.

This function inserts the coordinates into the <layername>_SDOGEOM table, tessellates the geometry (creates the index), and returns a unique SDO_GID corresponding to the geometry.

You do not need special privileges to execute this function. However, the user who compiles it does need appropriate privileges to read and write into the database.

Related Topics

SDO_WINDOW.CLEAN_WINDOW

Purpose

This procedure drops the four tables created in the layer for the query window.

Syntax

SDO_WINDOW.CLEAN_WINDOW (layername);

Keywords and Parameters

layername

Specifies the name of the window layer that needs to be dropped. Datatype is VARCHAR2.

Returns

Usage Notes

Typically, you would build a layer once, and then build multiple windows and perform multiple queries using that layer. After finishing all queries, you can execute the SDO_WINDOW.CLEAN_WINDOW procedure to drop the tables.

Related Topics

SDO_WINDOW.CREATE_WINDOW_LAYER

Purpose

This procedure creates the necessary tables which constitute a layer used for defining a query window.

Syntax

SDO_WINDOW.CREATE_WINDOW_LAYER (SDO_DIMNUM1, SDO_LB1, SDO_UB1, SDO_TOLERANCE1, SDO_DIMNAME, SDO_DIMNUM2, SDO_LB2, SDO_UB2, SDO_TOLERANCE2, SDO_DIMNAME2)

Keywords and Parameters

layername

Specifies the name of the window layer to be created. The layername is used to construct the for tables associated with the layer. Datatype is VARCHAR2.

SDO_LB1, SDO_UB1

Specifies the lower and upper bounds of this dimension. Datatype is NUMBER.

SDO_TOLERANCE1, SDO_TOLERANCE2

Specifies the allowable variance of ordinate values within each dimension. Datatype is NUMBER.

SDO_DIMNAME1, SDO_DIMNAME2

Specifies the name of the dimension. Datatype is VARCHAR2.

Returns

Usage Notes

Because the <layername>_SDODIM table is initialized with the dimension and the bound information, only those queries which are in the same dimension should be queried against this layer. If you wish to issue a query with respect to a different dimension, you must create a new layer.

Related Topics

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