org.geotools.data.db2.filter
Class SQLEncoderDB2

java.lang.Object
  org.geotools.filter.SQLEncoder
      org.geotools.data.db2.filter.SQLEncoderDB2

All Implemented Interfaces:

FilterVisitor

public class SQLEncoderDB2

extends SQLEncoder

implements FilterVisitor

Generate a WHERE clause for DB2 Spatial Extender based on a spatial filter.

The following spatial filter operations are supported:

• GEOMETRY_BBOX
• GEOMETRY_CONTAINS
• GEOMETRY_CROSSES
• GEOMETRY_DISJOINT
• GEOMETRY_EQUALS
• GEOMETRY_INTERSECTS
• GEOMETRY_OVERLAPS
• GEOMETRY_TOUCHES
• GEOMETRY_WITHIN
• GEOMETRY_DWITHIN

Author:

David Adler - IBM Corporation

Field Summary

Fields inherited from class org.geotools.filter.SQLEncoder

mapper, out

Constructor Summary

SQLEncoderDB2()
Construct an SQLEncoderDB2

SQLEncoderDB2(java.io.Writer out, Filter filter)
Construct an SQLEncoderDB2 that does the encoding (through superclass) directly based on the filter parameter.

Method Summary

protected FilterCapabilities	createFilterCapabilities() Sets the DB2 filter capabilities.
void	setSelectivityClause(java.lang.String string) Sets a SELECTIVITY clause that can be included with the spatial predicate to influence the query optimizer to exploit a spatial index if it exists.
void	setSRID(int srid) Set the value of the srid value to be used if a DB2 Spatial Extender geometry needs to be constructed.
void	visit(GeometryFilter filter) Generate a WHERE clause for the input GeometryFilter.
void	visit(LikeFilter filter) Writes the SQL for the Like Filter.
void	visitLiteralGeometry(LiteralExpression expression) Construct an ST_Geometry from the WKT representation of a literal expression

Methods inherited from class org.geotools.filter.SQLEncoder

encode, encode, escapeName, getCapabilities, getColnameEscape, setColnameEscape, setFIDMapper, setSqlNameEscape, visit, visit, visit, visit, visit, visit, visit, visit, visit, visit, visit

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Methods inherited from interface org.geotools.filter.FilterVisitor

visit, visit, visit, visit, visit, visit, visit, visit, visit, visit, visit

Constructor Detail

SQLEncoderDB2

public SQLEncoderDB2()

Construct an SQLEncoderDB2

SQLEncoderDB2

public SQLEncoderDB2(java.io.Writer out,
                     Filter filter)
              throws SQLEncoderException

Construct an SQLEncoderDB2 that does the encoding (through superclass) directly based on the filter parameter.

Parameters:

out - a writer object

filter - query filter to be encoded

Throws:

SQLEncoderException

Method Detail

visit

public void visit(LikeFilter filter)
           throws java.lang.RuntimeException

Writes the SQL for the Like Filter. Assumes the current java implemented wildcards for the Like Filter: . for multi and .? for single. And replaces them with the SQL % and _, respectively.

Specified by:

visit in interface FilterVisitor

Overrides:

visit in class SQLEncoder

Parameters:

filter - the Like Filter to be visited.

Throws:

java.lang.RuntimeException - if writing the expression fails.

visit

public void visit(GeometryFilter filter)
           throws java.lang.RuntimeException

Generate a WHERE clause for the input GeometryFilter.

The following spatial filter operations are supported:

• GEOMETRY_BBOX
• GEOMETRY_CONTAINS
• GEOMETRY_CROSSES
• GEOMETRY_DISJOINT
• GEOMETRY_EQUALS
• GEOMETRY_INTERSECTS
• GEOMETRY_OVERLAPS
• GEOMETRY_TOUCHES
• GEOMETRY_WITHIN
• GEOMETRY_DWITHIN
• GEOMETRY_BEYOND

Specified by:

visit in interface FilterVisitor

Overrides:

visit in class SQLEncoder

Parameters:

filter - The geometry filter to be processed.

Throws:

java.lang.RuntimeException - for IO exception

See Also:

FilterVisitor.visit(org.geotools.filter.GeometryFilter)

visitLiteralGeometry

public void visitLiteralGeometry(LiteralExpression expression)
                          throws java.io.IOException

Construct an ST_Geometry from the WKT representation of a literal expression

Overrides:

visitLiteralGeometry in class SQLEncoder

Parameters:

expression - the expression turn into an ST_Geometry.

Throws:

java.io.IOException - Passes back exception if generated by this.out.write()

setSRID

public void setSRID(int srid)

Set the value of the srid value to be used if a DB2 Spatial Extender geometry needs to be constructed.

This is specifically the DB2 Spatial Extender spatial reference system identifier and not a coordinate system identifier ala EPSG.

Parameters:

srid - Spatial reference system identifier to be used.

createFilterCapabilities

protected FilterCapabilities createFilterCapabilities()

Sets the DB2 filter capabilities.

Overrides:

createFilterCapabilities in class SQLEncoder

Returns:

FilterCapabilities for DB2

setSelectivityClause

public void setSelectivityClause(java.lang.String string)

Sets a SELECTIVITY clause that can be included with the spatial predicate to influence the query optimizer to exploit a spatial index if it exists.

The parameter should be of the form:
"SELECTIVITY 0.001"
where the numeric value is the fraction of rows that will be returned by using the index scan. This doesn't have to be true. The value 0.001 is typically used to force the use of the spatial in all cases if the spatial index exists.

Parameters:

string - a selectivity clause