4 Loading Spatial Data

This chapter describes how to load spatial data into a database, including storing the data in a table with a column of type SDO_GEOMETRY. After you have loaded spatial data, you can create a spatial index for it and perform queries on it, as described in Chapter 5.

The process of loading data can be classified into two categories:

Bulk loading of data (see Section 4.1)

This process is used to load large volumes of data into the database and uses the SQL*Loader utility to load the data.
Transactional insert operations (see Section 4.2)

This process is typically used to insert relatively small amounts of data into the database using the INSERT statement in SQL.

Recommendations for loading and validating spatial data are described in Section 4.3.

4.1 Bulk Loading

Bulk loading can import large amounts of data into an Oracle database. Bulk loading is accomplished with the SQL*Loader utility. (For information about SQL*Loader, see Oracle Database Utilities.)

4.1.1 Bulk Loading SDO_GEOMETRY Objects

Example 4-1 is the SQL*Loader control file for loading four geometries. When this control file is used with SQL*Loader, it loads the same cola market geometries that are inserted using SQL statements in Example 2-1 in Section 2.1.

Example 4-1 Control File for a Bulk Load of Cola Market Geometries

LOAD DATA
INFILE *
TRUNCATE
CONTINUEIF NEXT(1:1) = '#'
INTO TABLE COLA_MARKETS
FIELDS TERMINATED BY '|'
TRAILING NULLCOLS (
mkt_id INTEGER EXTERNAL,
name CHAR,
shape COLUMN OBJECT
(
SDO_GTYPE INTEGER EXTERNAL,
SDO_ELEM_INFO VARRAY TERMINATED BY '|/'
(elements FLOAT EXTERNAL),
SDO_ORDINATES VARRAY TERMINATED BY '|/'
(ordinates FLOAT EXTERNAL)
)
)
begindata
 1|cola_a|
#2003|1|1003|3|/
#1|1|5|7|/
 2|cola_b|
#2003|1|1003|1|/
#5|1|8|1|8|6|5|7|5|1|/
 3|cola_c|
#2003|1|1003|1|/
#3|3|6|3|6|5|4|5|3|3|/
 4|cola_d|
#2003|1|1003|4|/
#8|7|10|9|8|11|/

Notes on Example 4-1:

The EXTERNAL keyword in the definition mkt_id INTEGER EXTERNAL means that each value to be inserted into the MKT_ID column (1, 2, 3, and 4 in this example) is an integer in human-readable form, not binary format.
In the data after begindata, each MKT_ID value is preceded by one space, because the CONTINUEIF NEXT(1:1) = '#' specification causes the first position of each data line to be ignored unless it is the number sign (#) continuation character.

Example 4-2 assumes that a table named POLY_4PT was created as follows:

CREATE TABLE POLY_4PT (GID VARCHAR2(32),
                       GEOMETRY SDO_GEOMETRY);

Assume that the ASCII data consists of a file with delimited columns and separate rows fixed by the limits of the table with the following format:

geometry rows:    GID, GEOMETRY

The coordinates in the GEOMETRY column represent polygons. Example 4-2 shows the control file for loading the data.

Example 4-2 Control File for a Bulk Load of Polygons

LOAD DATA 
 INFILE *
 TRUNCATE
 CONTINUEIF NEXT(1:1) = '#'
 INTO TABLE POLY_4PT
 FIELDS TERMINATED BY '|'
 TRAILING NULLCOLS (
  GID  INTEGER EXTERNAL,
  GEOMETRY COLUMN OBJECT 
   (
     SDO_GTYPE       INTEGER EXTERNAL, 
     SDO_ELEM_INFO   VARRAY TERMINATED BY '|/' 
       (elements     FLOAT EXTERNAL), 
     SDO_ORDINATES   VARRAY TERMINATED BY '|/' 
       (ordinates    FLOAT EXTERNAL) 
   )
)
begindata
 1|2003|1|1003|1|/
#-122.4215|37.7862|-122.422|37.7869|-122.421|37.789|-122.42|37.7866|
#-122.4215|37.7862|/
 2|2003|1|1003|1|/
#-122.4019|37.8052|-122.4027|37.8055|-122.4031|37.806|-122.4012|37.8052|
#-122.4019|37.8052|/
 3|2003|1|1003|1|/
#-122.426|37.803|-122.4242|37.8053|-122.42355|37.8044|-122.4235|37.8025|
#-122.426|37.803|/

4.1.2 Bulk Loading Point-Only Data in SDO_GEOMETRY Objects

Example 4-3 shows a control file for loading a table with point data.

Example 4-3 Control File for a Bulk Load of Point-Only Data

LOAD DATA 
 INFILE *
 TRUNCATE
 CONTINUEIF NEXT(1:1) = '#'
 INTO TABLE POINT
 FIELDS TERMINATED BY '|'
 TRAILING NULLCOLS (
  GID      INTEGER EXTERNAL,
  GEOMETRY COLUMN OBJECT 
   (
     SDO_GTYPE       INTEGER EXTERNAL, 
     SDO_POINT COLUMN OBJECT
       (X            FLOAT EXTERNAL, 
        Y            FLOAT EXTERNAL)
   )
)

BEGINDATA
 1| 2001| -122.4215| 37.7862|
 2| 2001| -122.4019| 37.8052|
 3| 2001| -122.426| 37.803|
 4| 2001| -122.4171| 37.8034|
 5| 2001| -122.416151| 37.8027228|

4.2 Transactional Insert Operations Using SQL

Oracle Spatial uses standard Oracle tables that can be accessed or loaded with standard SQL syntax. This section contains examples of transactional insertions into columns of type SDO_GEOMETRY. This process is typically used to add relatively small amounts of data into the database.

The INSERT statement in Oracle SQL has a limit of 999 arguments. Therefore, you cannot create a variable-length array of more than 999 elements using the SDO_GEOMETRY constructor inside a transactional INSERT statement; however, you can insert a geometry using a host variable, and the host variable can be built using the SDO_GEOMETRY constructor with more than 999 values in the SDO_ORDINATE_ARRAY specification. (The host variable is an OCI, PL/SQL, or Java program variable.)

To perform transactional insertions of geometries, you can create a procedure to insert a geometry, and then invoke that procedure on each geometry to be inserted. Example 4-4 creates a procedure to perform the insert operation.

Example 4-4 Procedure to Perform a Transactional Insert Operation

CREATE OR REPLACE PROCEDURE
        INSERT_GEOM(GEOM SDO_GEOMETRY)
IS

BEGIN
  INSERT INTO TEST_1 VALUES (GEOM);
  COMMIT;
END;
/

Using the procedure created in Example 4-4, you can insert data by using a PL/SQL block, such as the one in Example 4-5, which loads a geometry into the variable named geom and then invokes the INSERT_GEOM procedure to insert that geometry.

Example 4-5 PL/SQL Block Invoking a Procedure to Insert a Geometry

DECLARE
geom SDO_geometry :=
  SDO_geometry (2003, null, null,
          SDO_elem_info_array (1,1003,3),
          SDO_ordinate_array (-109,37,-102,40));
BEGIN
  INSERT_GEOM(geom);
  COMMIT;
END;
/

For additional examples with various geometry types, see the following:

Rectangle: Example 2-6 in Section 2.7.1
Polygon with a hole: Example 2-7 in Section 2.7.2
Compound line string: Example 2-8 in Section 2.7.3
Compound polygon: Example 2-9 in Section 2.7.4
Point: Example 2-10 and Example 2-11 in Section 2.7.5
Oriented point: Example 2-12 in Section 2.7.6
Type 0 (zero) element: Example 2-14 in Section 2.7.7

4.3 Recommendations for Loading and Validating Spatial Data

The recommended procedure for loading and validating spatial data is as follows:

Load the data, using a method described in Section 4.1 or Section 4.2.
Use the SDO_GEOM.VALIDATE_GEOMETRY_WITH_CONTEXT function or the SDO_GEOM.VALIDATE_LAYER_WITH_CONTEXT procedure on all spatial data loaded into the database.
For any geometries with the wrong orientation or an invalid ETYPE or GTYPE value, use SDO_MIGRATE.TO_CURRENT on these invalid geometries to fix them.
For any geometries that are invalid for other reasons, use SDO_UTIL.RECTIFY_GEOMETRY to fix these geometries.

For detailed information about using any of these subprograms, see the usage notes in its reference information section.