org.geotools.jdbc
Class SQLDialect

Object
  SQLDialect

Direct Known Subclasses:

BasicSQLDialect, DB2SQLDialect, H2Dialect, MySQLDialect, PreparedStatementSQLDialect

public abstract class SQLDialect
extends Object

The driver used by JDBCDataStore to directly communicate with the database.

This class encapsulates all the database specific operations that JDBCDataStore needs to function. It is implemented on a per-database basis.

Type Mapping

One of the jobs of a dialect is to map sql types to java types and vice versa. This abstract implementation provides default mappings for "primitive" java types. The following mappings are provided. A '*' denotes that the mapping is the default java to sql mapping as well.

• VARCHAR -> String *
• CHAR -> String
• LONGVARCHAR -> String
• BIT -> Boolean
• BOOLEAN -> Boolean *
• SMALLINT -> Short *
• TINYINT -> Short
• INTEGER -> Integer *
• BIGINT -> Long *
• REAL -> Float *
• DOUBLE -> Double *
• FLOAT -> Double
• NUMERIC -> BigDecimal *
• DECIMAL -> BigDecimal
• DATE -> java.sql.Date *
• TIME -> java.sql.Time *
• TIMESTAMP -> java.sql.Timestmap *

Subclasses should extend (not override) the following methods to configure the mappings:

• registerSqlTypeToClassMappings(Map)
• registerSqlTypeNameToClassMappings(Map)
• registerClassToSqlMappings(Map)

This class is intended to be stateless, therefore subclasses should not maintain any internal state. If for some reason a subclass must keep some state around (not recommended), it must ensure that the state is accessed in a thread safe manner.

Author:

Justin Deoliveira, The Open Planning Project

Field Summary

static FilterCapabilities	BASE_DBMS_CAPABILITIES The basic filter capabilities all databases should have
protected JDBCDataStore	dataStore The datastore using the dialect
protected static Logger	LOGGER

Constructor Summary

protected

SQLDialect(JDBCDataStore dataStore) Creates the dialect.

Method Summary

protected void	addSupportedHints(Set<Hints.Key> hints) Add hints to the JDBC Feature Source.
void	applyLimitOffset(StringBuffer sql, int limit, int offset) Alters the query provided so that limit and offset are natively dealt with.
CoordinateReferenceSystem	createCRS(int srid, Connection cx) Turns the specified srid into a CoordinateReferenceSystem, or returns null if not possible.
abstract Envelope	decodeGeometryEnvelope(ResultSet rs, int column, Connection cx) Decodes the result of a spatial extent function in a SELECT statement.
Geometry	decodeGeometryValue(GeometryDescriptor descriptor, ResultSet rs, int column, GeometryFactory factory, Connection cx) Decodes a geometry value from the result of a query specifying the column as an index.
abstract Geometry	decodeGeometryValue(GeometryDescriptor descriptor, ResultSet rs, String column, GeometryFactory factory, Connection cx) Decodes a geometry value from the result of a query.
void	encodeColumnAlias(String raw, StringBuffer sql) Encodes the alias of a column in an sql query.
void	encodeColumnName(String raw, StringBuffer sql) Deprecated. use encodeColumnName(String, String, StringBuffer).
void	encodeColumnName(String prefix, String raw, StringBuffer sql) Encodes the name of a column in an SQL statement.
void	encodeColumnType(String sqlTypeName, StringBuffer sql) Encodes the type of a column in an SQL CREATE TABLE statement.
void	encodeGeometryColumn(GeometryDescriptor gatt, int srid, StringBuffer sql) Deprecated. use encodeGeometryColumn(GeometryDescriptor, String, int, StringBuffer)
void	encodeGeometryColumn(GeometryDescriptor gatt, String prefix, int srid, Hints hints, StringBuffer sql) Encodes the name of a geometry column in a SELECT statement.
void	encodeGeometryColumn(GeometryDescriptor gatt, String prefix, int srid, StringBuffer sql) Deprecated. use encodeGeometryColumn(GeometryDescriptor, String, int, Hints, StringBuffer)
void	encodeGeometryColumnGeneralized(GeometryDescriptor gatt, int srid, StringBuffer sql, Double distance) Deprecated. use encodeGeometryColumnGeneralized(GeometryDescriptor, String, int, StringBuffer, Double)
void	encodeGeometryColumnGeneralized(GeometryDescriptor gatt, String prefix, int srid, StringBuffer sql, Double distance)
void	encodeGeometryColumnSimplified(GeometryDescriptor gatt, int srid, StringBuffer sql, Double distance) Deprecated. use encodeGeometryColumnSimplified(GeometryDescriptor, String, int, StringBuffer, Double)
void	encodeGeometryColumnSimplified(GeometryDescriptor gatt, String prefix, int srid, StringBuffer sql, Double distance)
abstract void	encodeGeometryEnvelope(String tableName, String geometryColumn, StringBuffer sql) Encodes the spatial extent function of a geometry column in a SELECT statement.
void	encodeJoin(Join.Type joinType, StringBuffer sql) Encodes the syntax for a join between two tables.
void	encodePostColumnCreateTable(AttributeDescriptor att, StringBuffer sql) Encodes anything post a column in a CREATE TABLE statement.
void	encodePostCreateTable(String tableName, StringBuffer sql) Encodes anything post a CREATE TABLE statement.
void	encodePostSelect(SimpleFeatureType featureType, StringBuffer sql) Encodes anything after the SELECT clause and before the FROM clause.
void	encodePrimaryKey(String column, StringBuffer sql) Encodes the primary key definition in a CREATE TABLE statement.
void	encodeSchemaName(String raw, StringBuffer sql) Encodes the name of a schema in an SQL statement.
void	encodeTableAlias(String raw, StringBuffer sql) Encodes the alias of a table in an sql query.
void	encodeTableName(String raw, StringBuffer sql) Encodes the name of a table in an SQL statement.
int	getDefaultVarcharSize() Determines the default length that a varchar field should be when creating datastore tables from feature types.
Integer	getGeometrySRID(String schemaName, String tableName, String columnName, Connection cx) Returns the spatial reference system identifier (srid) for a particular geometry column.
String	getGeometryTypeName(Integer type) Returns the name of a geometric type based on its integer constant.
Object	getLastAutoGeneratedValue(String schemaName, String tableName, String columnName, Connection cx) Obtains the last value of an auto generated column.
Class<?>	getMapping(ResultSet columnMetaData, Connection cx) Determines the class mapping for a particular column of a table.
String	getNameEscape() Returns the string used to escape names.
Object	getNextAutoGeneratedValue(String schemaName, String tableName, String columnName, Connection cx) Obtains the next value of an auto generated column.
Object	getNextSequenceValue(String schemaName, String sequenceName, Connection cx) Obtains the next value of a sequence, incrementing the sequence to the next state in the process.
List<ReferencedEnvelope>	getOptimizedBounds(String schema, SimpleFeatureType featureType, Connection cx) Returns the bounds of all geometry columns in the layer using any approach that proves to be faster than the plain bounds aggregation (e.g., better than the "plain select extent(geom) from table" on PostGIS), or null if none exists or the fast method has not been enabled (e.g., if the fast method is just an estimate of the bounds you probably want the user to enable it manually)
String	getSequenceForColumn(String schemaName, String tableName, String columnName, Connection cx) Determines the name of the sequence (if any) which is used to increment generate values for a table column.
void	handleUserDefinedType(ResultSet columnMetaData, ColumnMetadata metadata, Connection cx) Handles the mapping for a user defined type.
boolean	includeTable(String schemaName, String tableName, Connection cx) Determines if the specified table should be included in those published by the datastore.
void	initializeConnection(Connection cx) Initializes a newly created database connection.
boolean	isAutoCommitQuery() Determine if a read query should be set to autocommit.
boolean	isLimitOffsetSupported() Returns true if this dialect can encode both Query.getStartIndex() and Query.getMaxFeatures() into native SQL.
boolean	lookupGeneratedValuesPostInsert() Controls whether keys are looked up post or pre insert.
protected String	ne() Quick accessor for getNameEscape().
void	postCreateAttribute(AttributeDescriptor att, String tableName, String schemaName, Connection cx) Callback which executes after an attribute descriptor has been built from a table column.
void	postCreateFeatureType(SimpleFeatureType featureType, DatabaseMetaData metadata, String schemaName, Connection cx) Callback which executes after a feature type has been built from a database table.
void	postCreateTable(String schemaName, SimpleFeatureType featureType, Connection cx) Callback to execute any additional sql statements post a create table statement.
void	registerAggregateFunctions(Map<Class<? extends FeatureVisitor>,String> aggregates) Registers the set of aggregate functions the dialect is capable of handling.
void	registerClassToSqlMappings(Map<Class<?>,Integer> mappings) Registers the java type to sql type mappings that the datastore uses when reading and writing objects to and from the database
void	registerSqlTypeNameToClassMappings(Map<String,Class<?>> mappings) Registers the sql type name to java type mappings that the dialect uses when reading and writing objects to and from the database.
void	registerSqlTypeToClassMappings(Map<Integer,Class<?>> mappings) Registers the sql type to java type mappings that the dialect uses when reading and writing objects to and from the database.
void	registerSqlTypeToSqlTypeNameOverrides(Map<Integer,String> overrides) Registers any overrides that should occur when mapping an integer sql type value to an underlying sql type name.

Methods inherited from class Object

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

Field Detail

LOGGER

protected static final Logger LOGGER

BASE_DBMS_CAPABILITIES

public static FilterCapabilities BASE_DBMS_CAPABILITIES

The basic filter capabilities all databases should have

dataStore

protected JDBCDataStore dataStore

The datastore using the dialect

Constructor Detail

SQLDialect

protected SQLDialect(JDBCDataStore dataStore)

Creates the dialect.

Parameters:

dataStore - The dataStore using the dialect.

Method Detail

initializeConnection

public void initializeConnection(Connection cx)
                          throws SQLException

Initializes a newly created database connection.

Subclasses should override this method if there is some additional action that needs to be taken when a new connection to the database is created. The default implementation does nothing.

Parameters:

cx - The new database connection.

Throws:

SQLException

includeTable

public boolean includeTable(String schemaName,
                            String tableName,
                            Connection cx)
                     throws SQLException

Determines if the specified table should be included in those published by the datastore.

This method returns true if the table should be published as a feature type, otherwise it returns false. Subclasses should override this method, this default implementation returns true.

A database connection is provided to the dialect but it should not be closed. However any statements objects or result sets that are instantiated from it must be closed.

Parameters:

schemaName - The schema of the table, might be null..

tableName - The name of the table.

cx - Database connection.

Throws:

SQLException

registerSqlTypeNameToClassMappings

public void registerSqlTypeNameToClassMappings(Map<String,Class<?>> mappings)

Registers the sql type name to java type mappings that the dialect uses when reading and writing objects to and from the database.

Subclasses should extend (not override) this method to provide additional mappings, or to override mappings provided by this implementation. This implementation provides the following mappings:

getMapping

public Class<?> getMapping(ResultSet columnMetaData,
                           Connection cx)
                    throws SQLException

Determines the class mapping for a particular column of a table.

Implementing this method is optional. It is used to allow database to perform custom type mappings based on various column metadata. It is called before the mappings registered in registerSqlTypeToClassMappings(Map) and #registerSqlTypeNameToClassMappings(Map) are used to determine the mapping. Subclasses should implement as needed, this default implementation returns null.

The columnMetaData argument is provided from {@link DatabaseMetaData#getColumns(String, String, String, String)}.

Parameters:

columnMetaData - The column metadata

The - connection used to retrieve the metadata

Returns:

The class mapped to the to column, or null.

Throws:

SQLException

handleUserDefinedType

public void handleUserDefinedType(ResultSet columnMetaData,
                                  ColumnMetadata metadata,
                                  Connection cx)
                           throws SQLException

Handles the mapping for a user defined type.

This method is called after getMapping(ResultSet, Connection) but before the rest of the type mapping heuristics are applied.

Implementing this method is optional. It is used to allow for handling user defined types or "DOMAINS". Dialects that implement this method should set the appropriate information on the metadata object to allow the column to be mapped via teh regular type mapping heuristics.

Parameters:

columnMetaData - The column metdata.

metadata - The column metadata object that collections mapping information.

cx - The database connection, not to be closed.

Throws:

SQLException

registerSqlTypeToClassMappings

public void registerSqlTypeToClassMappings(Map<Integer,Class<?>> mappings)

Registers the sql type to java type mappings that the dialect uses when reading and writing objects to and from the database.

Subclasses should extend (not override) this method to provide additional mappings, or to override mappings provided by this implementation. This implementation provides the following mappings:

registerClassToSqlMappings

public void registerClassToSqlMappings(Map<Class<?>,Integer> mappings)

Registers the java type to sql type mappings that the datastore uses when reading and writing objects to and from the database. *

Subclasses should extend (not override) this method to provide additional mappings, or to override mappings provided by this implementation. This implementation provides the following mappings:

registerSqlTypeToSqlTypeNameOverrides

public void registerSqlTypeToSqlTypeNameOverrides(Map<Integer,String> overrides)

Registers any overrides that should occur when mapping an integer sql type value to an underlying sql type name.

The default implementation of this method does nothing. Subclasses should override in cases where:

• database type metadata does not provide enough information to properly map
• to support custom types (those not in Types)

registerAggregateFunctions

public void registerAggregateFunctions(Map<Class<? extends FeatureVisitor>,String> aggregates)

Registers the set of aggregate functions the dialect is capable of handling.

Aggregate functions are handled via visitors of special types. The aggregates maps the class of the visitor to the associated function name. This base implementation handles some of the well known mappings:

• UniqueVisitor -> "unique"
• CountVisitor -> "count"
• MaxVisitor -> "max"
• MinVisitor -> "min"
• SumVisitor -> "sum"

Subclasses should extend (not override) to provide additional functions.

getNameEscape

public String getNameEscape()

Returns the string used to escape names.

This value is used to escape any name in a query. This includes columns, tables, schemas, indexes, etc... If no escape is necessary this method should return the empty string, and never return null.

This default implementation returns a single double quote ("), subclasses must override to provide a different espcape.

ne

protected final String ne()

Quick accessor for getNameEscape().

encodeColumnName

public final void encodeColumnName(String raw,
                                   StringBuffer sql)

Deprecated. use encodeColumnName(String, String, StringBuffer).

Encodes the name of a column in an SQL statement.

This method wraps raw in the character provided by getNameEscape(). Subclasses usually dont override this method and instead override getNameEscape().

encodeColumnName

public void encodeColumnName(String prefix,
                             String raw,
                             StringBuffer sql)

Encodes the name of a column in an SQL statement.

This method wraps raw in the character provided by getNameEscape(). Subclasses usually don't override this method and instead override getNameEscape().

The prefix parameter may be null so subclasses that do override must handle that case.

encodeColumnType

public void encodeColumnType(String sqlTypeName,
                             StringBuffer sql)

Encodes the type of a column in an SQL CREATE TABLE statement.

The default implementation simply outputs the sqlTypeName argument as is. Subclasses may override this method. Such cases might include:

• A type definition requires some parameter, ex: size of a varchar
• The provided attribute (att) contains some additional restrictions that can be encoded in the type, ex: field length

Parameters:

sqlTypeName -

sql -

encodeColumnAlias

public void encodeColumnAlias(String raw,
                              StringBuffer sql)

Encodes the alias of a column in an sql query.

This default implementation uses the syntax:

as "alias"

. Subclasses should override to provide a different syntax.

encodeTableAlias

public void encodeTableAlias(String raw,
                             StringBuffer sql)

Encodes the alias of a table in an sql query.

This default implementation uses the syntax:

as "alias"

. Subclasses should override to provide a different syntax.

encodeTableName

public void encodeTableName(String raw,
                            StringBuffer sql)

Encodes the name of a table in an SQL statement.

This method wraps raw in the character provided by getNameEscape(). Subclasses usually dont override this method and instead override getNameEscape().

encodeSchemaName

public void encodeSchemaName(String raw,
                             StringBuffer sql)

Encodes the name of a schema in an SQL statement.

This method wraps raw in the character provided by getNameEscape(). Subclasses usually dont override this method and instead override getNameEscape().

getGeometryTypeName

public String getGeometryTypeName(Integer type)

Returns the name of a geometric type based on its integer constant.

The constant, type, is registered in registerSqlTypeNameToClassMappings(Map).

This default implementation returns null, subclasses should override.

getGeometrySRID

public Integer getGeometrySRID(String schemaName,
                               String tableName,
                               String columnName,
                               Connection cx)
                        throws SQLException

Returns the spatial reference system identifier (srid) for a particular geometry column.

This method is given a direct connection to the database. The connection must not be closed. However any statements or result sets instantiated from the connection must be closed.

In the event that the srid cannot be determined, this method should return null.

Parameters:

schemaName - The database schema, could be null.

tableName - The table, never null.

columnName - The column name, never null

cx - The database connection.

Throws:

SQLException

createCRS

public CoordinateReferenceSystem createCRS(int srid,
                                           Connection cx)
                                    throws SQLException

Turns the specified srid into a CoordinateReferenceSystem, or returns null if not possible.

The implementation might just use CRS.decode("EPSG:" + srid), but most spatial databases will have their own SRS database that can be queried as well.

As a rule of thumb you should override this method if your spatial database uses codes that are not part of the EPSG standard database, of if for some reason you deem it preferable to use your database definition instead of an official EPSG one.

Most overrides will try out to decode the official EPSG code first, and fall back on the custom database definition otherwise

Parameters:

srid -

Returns:

Throws:

SQLException

getOptimizedBounds

public List<ReferencedEnvelope> getOptimizedBounds(String schema,
                                                   SimpleFeatureType featureType,
                                                   Connection cx)
                                            throws SQLException,
                                                   IOException

Returns the bounds of all geometry columns in the layer using any approach that proves to be faster than the plain bounds aggregation (e.g., better than the "plain select extent(geom) from table" on PostGIS), or null if none exists or the fast method has not been enabled (e.g., if the fast method is just an estimate of the bounds you probably want the user to enable it manually)

Parameters:

schema - The database schema, if any, or null

featureType - The feature type containing the geometry columns whose bounds need to computed. Mind, it may be retyped and thus contain less geometry columns than the table

cx -

Returns:

a list of referenced envelopes (some of which may be null or empty)

Throws:

SQLException

IOException

encodeGeometryEnvelope

public abstract void encodeGeometryEnvelope(String tableName,
                                            String geometryColumn,
                                            StringBuffer sql)

Encodes the spatial extent function of a geometry column in a SELECT statement.

This method must also be sure to properly encode the name of the column with the encodeColumnName(String, StringBuffer) function.

Parameters:

tableName -

decodeGeometryEnvelope

public abstract Envelope decodeGeometryEnvelope(ResultSet rs,
                                                int column,
                                                Connection cx)
                                         throws SQLException,
                                                IOException

Decodes the result of a spatial extent function in a SELECT statement.

This method is given direct access to a result set. The column parameter is the index into the result set which contains the spatial extent value. The query for this value is build with the encodeGeometryEnvelope(String, String, StringBuffer) method.

This method must not read any other objects from the result set other then the one referenced by column.

Parameters:

rs - A result set

column - Index into the result set which points at the spatial extent value.

The - database connection.

Throws:

SQLException

IOException

encodeGeometryColumn

public final void encodeGeometryColumn(GeometryDescriptor gatt,
                                       int srid,
                                       StringBuffer sql)

Deprecated. use encodeGeometryColumn(GeometryDescriptor, String, int, StringBuffer)

Encodes the name of a geometry column in a SELECT statement.

This method should wrap the column name in any functions that are used to retrieve its value. For instance, often it is necessary to use the function asText, or asWKB when fetching a geometry.

This method must also be sure to properly encode the name of the column with the encodeColumnName(String, StringBuffer) function.

Example:

   
   sql.append( "asText(" );
   column( gatt.getLocalName(), sql );
   sql.append( ")" );
   
 

This default implementation simply uses the column name without any wrapping function, subclasses must override.

encodeGeometryColumn

public void encodeGeometryColumn(GeometryDescriptor gatt,
                                 String prefix,
                                 int srid,
                                 StringBuffer sql)

Deprecated. use encodeGeometryColumn(GeometryDescriptor, String, int, Hints, StringBuffer)

Encodes the name of a geometry column in a SELECT statement.

This method should wrap the column name in any functions that are used to retrieve its value. For instance, often it is necessary to use the function asText, or asWKB when fetching a geometry.

This method must also be sure to properly encode the name of the column with the encodeColumnName(String, String, StringBuffer) function.

Example:

   
   sql.append( "asText(" );
   column( gatt.getLocalName(), sql );
   sql.append( ")" );
   
 

This default implementation simply uses the column name without any wrapping function, subclasses must override.

encodeGeometryColumn

public void encodeGeometryColumn(GeometryDescriptor gatt,
                                 String prefix,
                                 int srid,
                                 Hints hints,
                                 StringBuffer sql)

Encodes the name of a geometry column in a SELECT statement.

This method should wrap the column name in any functions that are used to retrieve its value. For instance, often it is necessary to use the function asText, or asWKB when fetching a geometry.

This method must also be sure to properly encode the name of the column with the encodeColumnName(String, String, StringBuffer) function.

Example:

   
   sql.append( "asText(" );
   column( gatt.getLocalName(), sql );
   sql.append( ")" );
   
 

This default implementation calls the deprecated encodeGeometryColumn(GeometryDescriptor, String, int, StringBuffer) version of this method for backward compatibility reasons.

encodeGeometryColumnGeneralized

public final void encodeGeometryColumnGeneralized(GeometryDescriptor gatt,
                                                  int srid,
                                                  StringBuffer sql,
                                                  Double distance)

Deprecated. use encodeGeometryColumnGeneralized(GeometryDescriptor, String, int, StringBuffer, Double)

Encodes a generalized geometry using a DB provided SQL function if available If not supported, subclasses should not implement Only called if is supported Example:

   
   sql.append( "asText(generalize(" );
   column( gatt.getLocalName(), sql );
   sql.append( "," );
   sql.append(distance);
   sql.append( "))" );
   
 

encodeGeometryColumnGeneralized

public void encodeGeometryColumnGeneralized(GeometryDescriptor gatt,
                                            String prefix,
                                            int srid,
                                            StringBuffer sql,
                                            Double distance)

encodeGeometryColumnSimplified

public void encodeGeometryColumnSimplified(GeometryDescriptor gatt,
                                           int srid,
                                           StringBuffer sql,
                                           Double distance)

Deprecated. use encodeGeometryColumnSimplified(GeometryDescriptor, String, int, StringBuffer, Double)

Encodes a simplified geometry using a DB provided SQL function if available If not supported, subclasses should not implement Only called if is supported

See Also:

SQLDialect#encodeGeometryColumnGeneralized(GeometryDescriptor, StringBuffer, Double)

encodeGeometryColumnSimplified

public void encodeGeometryColumnSimplified(GeometryDescriptor gatt,
                                           String prefix,
                                           int srid,
                                           StringBuffer sql,
                                           Double distance)

decodeGeometryValue

public abstract Geometry decodeGeometryValue(GeometryDescriptor descriptor,
                                             ResultSet rs,
                                             String column,
                                             GeometryFactory factory,
                                             Connection cx)
                                      throws IOException,
                                             SQLException

Decodes a geometry value from the result of a query.

This method is given direct access to a result set. The column parameter is the index into the result set which contains the geometric value.

An implementation should deserialize the value provided by the result set into Geometry object. For example, consider an implementation which deserializes from well known text:

   String wkt = rs.getString( column );
   if ( wkt == null ) {
     return null;
   }
   return new WKTReader(factory).read( wkt );
   

Note that implementations must handle null values.

The factory parameter should be used to instantiate any geometry objects.

Throws:

IOException

SQLException

decodeGeometryValue

public Geometry decodeGeometryValue(GeometryDescriptor descriptor,
                                    ResultSet rs,
                                    int column,
                                    GeometryFactory factory,
                                    Connection cx)
                             throws IOException,
                                    SQLException

Decodes a geometry value from the result of a query specifying the column as an index.

See #decodeGeometryValue(GeometryDescriptor, ResultSet, String, GeometryFactory) for a more in depth description.

Throws:

IOException

SQLException

See Also:

#decodeGeometryValue(GeometryDescriptor, ResultSet, String, GeometryFactory)}.

encodePrimaryKey

public void encodePrimaryKey(String column,
                             StringBuffer sql)

Encodes the primary key definition in a CREATE TABLE statement.

Subclasses should override this method if need be, the default implementation does the following:

   
   encodeColumnName( column, sql );
   sql.append( " int PRIMARY KEY" );
   
 

encodeJoin

public void encodeJoin(Join.Type joinType,
                       StringBuffer sql)

Encodes the syntax for a join between two tables.

encodePostColumnCreateTable

public void encodePostColumnCreateTable(AttributeDescriptor att,
                                        StringBuffer sql)

Encodes anything post a column in a CREATE TABLE statement.

This is appended after the column name and type. Subclasses may choose to override this method, the default implementation does nothing.

Parameters:

att - The attribute corresponding to the column.

encodePostCreateTable

public void encodePostCreateTable(String tableName,
                                  StringBuffer sql)

Encodes anything post a CREATE TABLE statement.

This is appended to a CREATE TABLE statement after the column definitions. This default implementation does nothing, subclasses should override as need be.

encodePostSelect

public void encodePostSelect(SimpleFeatureType featureType,
                             StringBuffer sql)

Encodes anything after the SELECT clause and before the FROM clause.

This method does not nothing, subclass may override to add additional columns.

Parameters:

featureType - The feature type being queried.

postCreateTable

public void postCreateTable(String schemaName,
                            SimpleFeatureType featureType,
                            Connection cx)
                     throws SQLException,
                            IOException

Callback to execute any additional sql statements post a create table statement.

This method should be implemented by subclasses that need to do some post processing on the database after a table has been created. Examples might include:

• Creating a sequence for a primary key
• Registering geometry column metadata
• Creating a spatial index

A common case is creating an auto incrementing sequence for the primary key of a table. It should be noted that all tables created through the datastore use the column "fid" as the primary key.

A direct connection to the database is provided (cx). This connection must not be closed, however any statements or result sets instantiated from the connection must be closed.

Parameters:

schemaName - The name of the schema, may be null.

featureType - The feature type that has just been created on the database.

cx - Database connection.

Throws:

SQLException

IOException

postCreateAttribute

public void postCreateAttribute(AttributeDescriptor att,
                                String tableName,
                                String schemaName,
                                Connection cx)
                         throws SQLException

Callback which executes after an attribute descriptor has been built from a table column.

The result set columnMetadata should not be modified in any way (including scrolling) , it should only be read from.

This base implementation does nothing, subclasses should override as need be.

Parameters:

att - The built attribute descriptor.

tableName - The name of the table containing the column

schemaName - The name of the database scheam containing the table containing the column

cx - The database connection.

Throws:

SQLException

postCreateFeatureType

public void postCreateFeatureType(SimpleFeatureType featureType,
                                  DatabaseMetaData metadata,
                                  String schemaName,
                                  Connection cx)
                           throws SQLException

Callback which executes after a feature type has been built from a database table.

This base implementation does nothing, subclasses should override as need be.

Parameters:

featureType - The build feature type.

metadata - The database metadata.

schemaName - The name of the database scheam containing the table containing the column

cx - The database connection.

Throws:

SQLException

lookupGeneratedValuesPostInsert

public boolean lookupGeneratedValuesPostInsert()

Controls whether keys are looked up post or pre insert.

When a row is inserted into a table, and a key is automatically generated it can be looked up before the insert occurs, or after the insert has been made. Returning false will cause the lookup to occur before the insert via getNextAutoGeneratedValue(String, String, String, Connection). Returning true will cause the lookup to occur after the insert via getLastAutoGeneratedValue(String, String, String, Connection).

Subclasses returning false should implement:

• getNextAutoGeneratedValue(String, String, String, Connection)

Subclasses returning true should implement:

• getLastAutoGeneratedValue(String, String, String, Connection)

getNextAutoGeneratedValue

public Object getNextAutoGeneratedValue(String schemaName,
                                        String tableName,
                                        String columnName,
                                        Connection cx)
                                 throws SQLException

Obtains the next value of an auto generated column.

Implementations should determine the next value of a column for which values are automatically generated by the database.

This method is given a direct connection to the database, but this connection should never be closed. However any statements or result sets instantiated from the connection must be closed.

Implementations should handle the case where schemaName is null.

Parameters:

schemaName - The schema name, this might be null.

tableName - The name of the table.

columnName - The column.

cx - The database connection.

Returns:

The next value of the column, or null.

Throws:

SQLException

getLastAutoGeneratedValue

public Object getLastAutoGeneratedValue(String schemaName,
                                        String tableName,
                                        String columnName,
                                        Connection cx)
                                 throws SQLException

Obtains the last value of an auto generated column.

This method is only called when lookupGeneratedValuesPostInsert() returns true. Implementations should determine the previous value of a column for which was automatically generated by the database.

This method is given a direct connection to the database, but this connection should never be closed. However any statements or result sets instantiated from the connection must be closed.

Implementations should handle the case where schemaName is null.

Parameters:

schemaName - The schema name, this might be null.

tableName - The name of the table.

columnName - The column.

cx - The database connection.

Returns:

The previous value of the column, or null.

Throws:

SQLException

getSequenceForColumn

public String getSequenceForColumn(String schemaName,
                                   String tableName,
                                   String columnName,
                                   Connection cx)
                            throws SQLException

Determines the name of the sequence (if any) which is used to increment generate values for a table column.

This method should return null if no such sequence exists.

This method is given a direct connection to the database, but this connection should never be closed. However any statements or result sets instantiated from the connection must be closed.

Parameters:

schemaName - The schema name, this might be null.

tableName - The table name.

columnName - The column name.

cx - The database connection.

Throws:

SQLException

getNextSequenceValue

public Object getNextSequenceValue(String schemaName,
                                   String sequenceName,
                                   Connection cx)
                            throws SQLException

Obtains the next value of a sequence, incrementing the sequence to the next state in the process.

Implementations should determine the next value of a column for which values are automatically generated by the database.

This method is given a direct connection to the database, but this connection should never be closed. However any statements or result sets instantiated from the connection must be closed.

Implementations should handle the case where schemaName is null.

Parameters:

schemaName - The schema name, this might be null.

sequenceName - The name of the sequence.

cx - The database connection.

Returns:

The next value of the sequence, or null.

Throws:

SQLException

isLimitOffsetSupported

public boolean isLimitOffsetSupported()

Returns true if this dialect can encode both Query.getStartIndex() and Query.getMaxFeatures() into native SQL.

Returns:

applyLimitOffset

public void applyLimitOffset(StringBuffer sql,
                             int limit,
                             int offset)

Alters the query provided so that limit and offset are natively dealt with. This might mean simply appending some extra directive to the query, or wrapping it into a bigger one.

Parameters:

sql -

limit -

offset -

addSupportedHints

protected void addSupportedHints(Set<Hints.Key> hints)

Add hints to the JDBC Feature Source. A subclass can override possible hints (but not limited to) Hints.GEOMETRY_GENERALIZATION Hints.GEOMETRY_SIMPLIFICATION

Parameters:

hints -

getDefaultVarcharSize

public int getDefaultVarcharSize()

Determines the default length that a varchar field should be when creating datastore tables from feature types.

Some dialects allow no length to be specified for varchar fields (PostGIS for example) however others require a maximum length to be set.

Subclasses can override this method and either return -1 to specify that no length is required, or otherwise return an appropriate default length for varchars of that dialect.

isAutoCommitQuery

public boolean isAutoCommitQuery()

Determine if a read query should be set to autocommit.

Some databases (like postgres) want this enabled to respect fetch size. The default implementation is to return false.

Returns:

true if read queries should remain autocommit, false otherwise