SQLDialect (Geotools modules 27-SNAPSHOT API)

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:
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

Fields
Modifier and Type	Field and Description
`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

Constructors
Modifier Constructor and Description

protected SQLDialect(JDBCDataStore dataStore)
Creates the dialect.

Constructors
Modifier	Constructor and Description
`protected`	`SQLDialect(JDBCDataStore dataStore)` Creates the dialect.

Method Summary

All Methods Instance Methods Abstract Methods Concrete Methods
Modifier and Type	Method and Description
`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.
`boolean`	`canGroupOnGeometry()` Returns true if this database can "group by" on a Geometry column.
`boolean`	`canSimplifyPoints()` Returns if points can be returned in simplified form (e.g reduced precision, like TWKB encoding)
`Object`	`convertValue(Object value, AttributeDescriptor ad)` Convertes the given value to the target type.
`CoordinateReferenceSystem`	`createCRS(int srid, Connection cx)` Turns the specified srid into a `CoordinateReferenceSystem`, or returns `null` if not possible.
`void`	`createIndex(Connection cx, SimpleFeatureType schema, String databaseSchema, Index index)` Performs the class "create [unique] indexName on tableName(att1, att2, ..., attN)" call.
`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, Hints hints)` 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, Hints hints)` Decodes a geometry value from the result of a query.
`void`	`dropIndex(Connection cx, SimpleFeatureType schema, String databaseSchema, String indexName)` Drop the index.
`void`	`encodeColumnAlias(String raw, StringBuffer sql)` Encodes the alias of a column in an sql query.
`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`	`encodeCreateTable(StringBuffer sql)` Encodes the CREATE TABLE statement.
`void`	`encodeGeometryColumn(GeometryDescriptor gatt, String prefix, int srid, Hints hints, StringBuffer sql)` Encodes the name of a geometry column in a SELECT statement.
`void`	`encodeGeometryColumnGeneralized(GeometryDescriptor gatt, String prefix, int srid, StringBuffer sql, Double distance)`
`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.
`String`	`encodeNextSequenceValue(String schemaName, String sequenceName)` Encodes how to get the next sequence value from the DB.
`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.
`String`	`escapeName(String name)` Surrounds a name with the SQL escape string.
`Function<Object,Object>`	`getAggregateConverter(FeatureVisitor visitor, SimpleFeatureType featureType)` Returns a converter used to transform the results of an aggregation, for the given visitor and feature type.
`int`	`getDefaultVarcharSize()` Determines the default length that a varchar field should be when creating datastore tables from feature types.
`String[]`	`getDesiredTablesType()`
`int`	`getGeometryDimension(String schemaName, String tableName, String columnName, Connection cx)` Returns the dimension of the coordinates in the geometry.
`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.
`List<Index>`	`getIndexes(Connection cx, String databaseSchema, String typeName)` Returns the list of indexes for a certain table.
`Object`	`getLastAutoGeneratedValue(String schemaName, String tableName, String columnName, Connection cx)` Obtains the last value of an auto generated column.
`Object`	`getLastAutoGeneratedValue(String schemaName, String tableName, String columnName, Connection cx, Statement st)` 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`	`getPkColumnValue(ResultSet rs, PrimaryKeyColumn pkey, int columnIdx)` Reads a primary key column value.
`protected PrimaryKey`	`getPrimaryKey(String typeName)`
`Filter`	`getRestrictions(ResultSet columnMetaData, Connection cx)` Allows the dialect to setup restrictions for attribute at hand
`protected Optional<List<Class>>`	`getResultTypes(FeatureVisitor visitor, SimpleFeatureType featureType)` Returns the list of aggregation output types for the given visitor and feature type (or an empty Optional if could not determine it)
`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.
`Integer`	`getSQLType(AttributeDescriptor ad)` Gives an opportunity to the dialect to do its own custom type mapping, based on the full description of the attribute.
`void`	`handleSelectHints(StringBuffer sql, SimpleFeatureType featureType, Query query)` Used to apply search hints on the fully generated SQL (complete of select, from, where, sort, limit/offset)
`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`	`isAggregatedSortSupported(String function)` Returns true if this dialect supports sorting together with the given aggregation function.
`boolean`	`isArray(AttributeDescriptor att)` Returns true if the attribute in question is an array.
`boolean`	`isAutoCommitQuery()` Determine if a read query should be set to autocommit.
`boolean`	`isGroupBySupported()` Returns true if this dialect supports group by clause.
`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`	`postDropTable(String schemaName, SimpleFeatureType featureType, Connection cx)` Callback which executes after a table has been dropped.
`void`	`preDropTable(String schemaName, SimpleFeatureType featureType, Connection cx)` Callback which executes before a table is about to be dropped.
`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. * Subclasses should extend (not override) this method to provide additional mappings, or to override mappings provided by this implementation.
`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.
`Filter[]`	`splitFilter(Filter filter, SimpleFeatureType schema)` Splits the filter into two parts, an encodable one, and a non encodable one.
`protected boolean`	`supportsSchemaForIndex()` Return `true` if the database supports individual schemas for indices.

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 cx - The connection used to retrieve the metadata Returns: The class mapped to the to column, or null. Throws: SQLException getRestrictions public Filter getRestrictions(ResultSet columnMetaData, Connection cx) throws SQLException Allows the dialect to setup restrictions for attribute at hand Parameters: columnMetaData - The column metadata cx - The connection used to retrieve the metadata Returns: The restriction, or null if no restriction applies 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 the 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" AverageVisitor -> "avg" StandardDeviationVisitor -> "stddev_pop" 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(). escapeName public String escapeName(String name) Surrounds a name with the SQL escape string. If the name contains the SQL escape string, the SQL escape string is duplicated. encodeColumnName public void encodeColumnName(String prefix, String raw, StringBuffer sql) Encodes the name of a column in an SQL statement. This method escapes raw using method escapeName(String). 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 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 escapes raw using method escapeName(String). 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 escapes raw using method escapeName(String). 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 getGeometryDimension public int getGeometryDimension(String schemaName, String tableName, String columnName, Connection cx) throws SQLException Returns the dimension of the coordinates in the geometry. Defaults to 2, subclasses can override it. 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 dimension cannot be determined, this method should return 2 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 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 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. 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. cx - The database connection. Throws: SQLException IOException 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( ")" ); encodeGeometryColumnGeneralized public void encodeGeometryColumnGeneralized(GeometryDescriptor gatt, String prefix, int srid, StringBuffer sql, Double distance) 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, Hints hints) 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, Hints hints) 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. encodeCreateTable public void encodeCreateTable(StringBuffer sql) Encodes the CREATE TABLE statement. Default implementation adds "CREATE TABLE" to the sql buffer. Subclasses may choose to override to handle db specific syntax. 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 preDropTable public void preDropTable(String schemaName, SimpleFeatureType featureType, Connection cx) throws SQLException Callback which executes before a table is about to be dropped. This base implementation does nothing, subclasses should override as need be. Parameters: schemaName - The database schema containing the table. featureType - The featureType/table being dropped. cx - The database connection. Throws: SQLException postDropTable public void postDropTable(String schemaName, SimpleFeatureType featureType, Connection cx) throws SQLException Callback which executes after a table has been dropped. This base implementation does nothing, subclasses should override as need be. Parameters: schemaName - The database schema containing the table. featureType - The featureType/table being dropped. 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, Statement st) 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. st - The statement used for the insert Returns: The previous 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 encodeNextSequenceValue public String encodeNextSequenceValue(String schemaName, String sequenceName) Encodes how to get the next sequence value from the DB. Implementations should handle the case where schemaName is null. isLimitOffsetSupported public boolean isLimitOffsetSupported() Returns true if this dialect can encode both Query.getStartIndex() and Query.getMaxFeatures() into native SQL. isAggregatedSortSupported public boolean isAggregatedSortSupported(String function) Returns true if this dialect supports sorting together with the given aggregation function. isGroupBySupported public boolean isGroupBySupported() Returns true if this dialect supports group by clause. 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. 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 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 supportsSchemaForIndex protected boolean supportsSchemaForIndex() Return true if the database supports individual schemas for indices. The SQL encoding would be CREATE INDEX SCHEMANAME.INDEXNAME ON .... The default is false and the encoding is CREATE INDEX INDEXNAME ON .... Returns: true or false createIndex public void createIndex(Connection cx, SimpleFeatureType schema, String databaseSchema, Index index) throws SQLException Performs the class "create [unique] indexName on tableName(att1, att2, ..., attN)" call. Subclasses can override to handle special indexes (like spatial ones) and/or the hints Throws: SQLException dropIndex public void dropIndex(Connection cx, SimpleFeatureType schema, String databaseSchema, String indexName) throws SQLException Drop the index. Subclasses can override to handle extra syntax or db specific situations Throws: SQLException getIndexes public List<Index> getIndexes(Connection cx, String databaseSchema, String typeName) throws SQLException Returns the list of indexes for a certain table. Subclasses can override to add support for db specific hints Throws: SQLException handleSelectHints public void handleSelectHints(StringBuffer sql, SimpleFeatureType featureType, Query query) Used to apply search hints on the fully generated SQL (complete of select, from, where, sort, limit/offset) getDesiredTablesType public String[] getDesiredTablesType() Returns: Table types filtered from jdbc DatabaseMetaData splitFilter public Filter[] splitFilter(Filter filter, SimpleFeatureType schema) Splits the filter into two parts, an encodable one, and a non encodable one. The default implementation uses the filter capabilities to split the filter, subclasses can implement their own logic if need be. getPrimaryKey protected PrimaryKey getPrimaryKey(String typeName) throws IOException Throws: IOException getPkColumnValue public String getPkColumnValue(ResultSet rs, PrimaryKeyColumn pkey, int columnIdx) throws SQLException Reads a primary key column value. By default uses ResultSet.getString(int), subclasses can use a more efficient way should they wish to Throws: SQLException canSimplifyPoints public boolean canSimplifyPoints() Returns if points can be returned in simplified form (e.g reduced precision, like TWKB encoding) getResultTypes protected Optional<List<Class>> getResultTypes(FeatureVisitor visitor, SimpleFeatureType featureType) Returns the list of aggregation output types for the given visitor and feature type (or an empty Optional if could not determine it) getAggregateConverter public Function<Object,Object> getAggregateConverter(FeatureVisitor visitor, SimpleFeatureType featureType) Returns a converter used to transform the results of an aggregation, for the given visitor and feature type. The default implementation returns an identify function, databases with type system limitations can use it to convert the result to the desired type. Implementations overriding this method might use getResultTypes(FeatureVisitor, SimpleFeatureType) to compute the expected result type of the aggregation expressions. Parameters: visitor - featureType - Returns: getSQLType public Integer getSQLType(AttributeDescriptor ad) Gives an opportunity to the dialect to do its own custom type mapping, based on the full description of the attribute. Defaults to return null, subclasses can override Parameters: ad - The attribute descriptor Returns: A SQL type from Types, or null if customization is needed isArray public boolean isArray(AttributeDescriptor att) Returns true if the attribute in question is an array. By default comparers the JDBCDataStore.JDBC_NATIVE_TYPE stored in the attribute user data with Types.ARRAY, but subclasses can override to use a different approach. convertValue public Object convertValue(Object value, AttributeDescriptor ad) Convertes the given value to the target type. The default implementation uses converters to match the attribute descriptor binding, subclasses can override. canGroupOnGeometry public boolean canGroupOnGeometry() Returns true if this database can "group by" on a Geometry column. Defaults to false, specific implementations with this capability should override

Class SQLDialect

Type Mapping

Field Summary

Constructor Summary

Method Summary

Methods inherited from class Object

Field Detail

LOGGER

BASE_DBMS_CAPABILITIES

dataStore

Constructor Detail

SQLDialect

Method Detail

initializeConnection

includeTable

registerSqlTypeNameToClassMappings

getMapping

getRestrictions

handleUserDefinedType

registerSqlTypeToClassMappings

registerClassToSqlMappings

registerSqlTypeToSqlTypeNameOverrides

registerAggregateFunctions

getNameEscape

ne

escapeName

encodeColumnName

encodeColumnType

encodeColumnAlias

encodeTableAlias

encodeTableName

encodeSchemaName

getGeometryTypeName

getGeometrySRID

getGeometryDimension

createCRS

getOptimizedBounds

encodeGeometryEnvelope

decodeGeometryEnvelope

encodeGeometryColumn

encodeGeometryColumnGeneralized

encodeGeometryColumnSimplified

decodeGeometryValue

decodeGeometryValue

encodePrimaryKey

encodeJoin

encodeCreateTable

encodePostColumnCreateTable

encodePostCreateTable

encodePostSelect

postCreateTable

postCreateAttribute

postCreateFeatureType

preDropTable

postDropTable

lookupGeneratedValuesPostInsert

getNextAutoGeneratedValue

getLastAutoGeneratedValue

getLastAutoGeneratedValue

getSequenceForColumn

getNextSequenceValue

encodeNextSequenceValue

isLimitOffsetSupported

isAggregatedSortSupported

isGroupBySupported

applyLimitOffset

addSupportedHints

getDefaultVarcharSize

isAutoCommitQuery

supportsSchemaForIndex

createIndex

dropIndex

getIndexes

handleSelectHints

getDesiredTablesType

splitFilter

getPrimaryKey

getPkColumnValue

canSimplifyPoints

getResultTypes