Class DuckDBDialect
- Direct Known Subclasses:
GeoParquetDialect
This dialect implements the core SQL operations for DuckDB, with a focus on spatial functionality. It provides implementations for:
- Geometry handling (WKB encoding/decoding, spatial function mapping)
- SQL type conversions for geometry classes
- Filter and query translation
- Extension management (spatial, etc.)
- Optimized bounds calculations
- Geometry simplification for rendering
This base dialect is extended by format-specific dialects like GeoParquetDialect
to provide specialized
functionality for different data formats while sharing the common DuckDB handling code.
DuckDB is particularly well-suited for analytical workloads and includes excellent built-in support for spatial operations and columnar file formats like Parquet.
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Field Summary
Fields inherited from class SQLDialect
BASE_DBMS_CAPABILITIES, dataStore, forceLongitudeFirst, LOGGER, UNWRAPPER_NOT_FOUND, uwMap
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Constructor Summary
Constructors -
Method Summary
Modifier and TypeMethodDescriptionprotected 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.Creates the filter encoder to be used by the datastore when encoding query predicates.decodeGeometryEnvelope
(ResultSet rs, int column, Connection cx) Decodes the result of a spatial extent function in a SELECT statement.decodeGeometryValue
(GeometryDescriptor descriptor, ResultSet rs, String column, GeometryFactory factory, Connection cx, Hints hints) Decodes a geometry value from the result of a query.encodeColumnName
(String prefix, String raw) 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) protected void
encodeGeometryColumnInternal
(GeometryDescriptor gatt, String prefix, Hints hints, boolean forceMulti, StringBuffer sql) void
encodeGeometryColumnSimplified
(GeometryDescriptor gatt, String prefix, int srid, StringBuffer sql, Double distance) void
encodeGeometryEnvelope
(String tableName, String geometryColumn, StringBuffer sql) Encodes the spatial extent function of a geometry column in a SELECT statement.void
encodeGeometryValue
(Geometry value, int dimension, int srid, StringBuffer sql) Encodes a geometry value in an sql statement.void
Encodes anything post a column in a CREATE TABLE statement.void
encodePrimaryKey
(String column, StringBuffer sql) Encodes the primary key definition in a CREATE TABLE statement.escapeName
(String name) Surrounds a name with the SQL escape string.getGeometrySRID
(String schemaName, String tableName, String columnName, Connection cx) Returns the spatial reference system identifier (srid) for a particular geometry column.Class<?>
getMapping
(ResultSet columnMetaData, Connection cx) It is called before the mappings registered inregisterSqlTypeToClassMappings(Map)
andare used to determine the mapping. Subclasses should implement as needed, the default implementation returns {@code null}.
Returns the string used to escape names.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)boolean
includeTable
(String schemaName, String tableName, Connection cx) Determines if the specified table should be included in those published by the datastore.protected boolean
isConcreteGeometry
(Class<?> binding) boolean
Returns true if this dialect can encode both Query.getStartIndex() and Query.getMaxFeatures() into native SQL.protected ReferencedEnvelope
optimizedBounds
(SimpleFeatureType featureType, Connection cx) protected Geometry
protected Geometry
parseWKB
(GeometryFactory factory, Blob blob) void
registerClassToSqlMappings
(Map<Class<?>, Integer> mappings) void
registerSqlTypeToClassMappings
(Map<Integer, Class<?>> mappings) Appends a mapping ofTypes.STRUCT
tojava.sql.Struct.class
void
setScreenMapEnabled
(boolean screenMapEnabled) void
setSimplifyEnabled
(boolean simplifyEnabled) Methods inherited from class BasicSQLDialect
encodeValue, onDelete, onInsert, onSelect, onUpdate
Methods inherited from class SQLDialect
applyHintsOnVirtualTables, canGroupOnGeometry, canSimplifyPoints, convertValue, createCRS, createIndex, decodeGeometryValue, dropIndex, encodeColumnAlias, encodeColumnName, encodeColumnType, encodeCreateTable, encodeJoin, encodeNextSequenceValue, encodePostCreateTable, encodePostSelect, encodeSchemaName, encodeTableAlias, encodeTableName, getAggregateConverter, getDefaultVarcharSize, getDesiredTablesType, getGeometryDimension, getGeometryTypeName, getIndexes, getLastAutoGeneratedValue, getLastAutoGeneratedValue, getMapping, getNextAutoGeneratedValue, getNextSequenceValue, getPkColumnValue, getPrimaryKey, getRestrictions, getResultTypes, getSequenceForColumn, getSQLType, handleSelectHints, handleUserDefinedType, initializeConnection, isAggregatedSortSupported, isArray, isAutoCommitQuery, isGroupBySupported, lookupGeneratedValuesPostInsert, ne, postCreateAttribute, postCreateFeatureType, postCreateTable, postDropTable, preDropTable, registerAggregateFunctions, registerSqlTypeNameToClassMappings, registerSqlTypeToSqlTypeNameOverrides, splitFilter, supportsSchemaForIndex, unwrapConnection
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Constructor Details
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DuckDBDialect
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Method Details
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setScreenMapEnabled
public void setScreenMapEnabled(boolean screenMapEnabled) -
setSimplifyEnabled
public void setSimplifyEnabled(boolean simplifyEnabled) -
getDatabaseInitSql
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getNameEscape
Description copied from class:SQLDialect
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.
- Overrides:
getNameEscape
in classSQLDialect
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escapeName
Description copied from class:SQLDialect
Surrounds a name with the SQL escape string.If the name contains the SQL escape string, the SQL escape string is duplicated.
- Overrides:
escapeName
in classSQLDialect
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includeTable
Description copied from class:SQLDialect
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 returnsfalse
. Subclasses should override this method, this default implementation returnstrue
.
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.
- Overrides:
includeTable
in classSQLDialect
- Parameters:
schemaName
- The schema of the table, might benull
..tableName
- The name of the table.cx
- Database connection.- Throws:
SQLException
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addSupportedHints
Description copied from class:SQLDialect
Add hints to the JDBC Feature Source. A subclass can overridepossible hints (but not limited to)
- Overrides:
addSupportedHints
in classSQLDialect
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getMapping
It is called before the mappings registered inregisterSqlTypeToClassMappings(Map)
andare used to determine the mapping. Subclasses should implement as needed, the default implementation returns {@code null}.
- Overrides:
getMapping
in classSQLDialect
- Parameters:
columnMetaData
- The column metadatacx
- The connection used to retrieve the metadata- Returns:
- The class mapped to the to column, or
null
. - Throws:
SQLException
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registerSqlTypeToClassMappings
Appends a mapping ofTypes.STRUCT
tojava.sql.Struct.class
Support for struct is limited and results in GeoServer WMS and WFS to interpret it as a String literal. For example, a "bbox"
Struct
attribute value withSQL type name
as STRUCT(xmin FLOAT, xmax FLOAT, ymin FLOAT, ymax FLOAT) will be encoded as <bbox>{xmin=-63.005005, xmax=-63.004997, ymin=-40.81569, ymax=-40.81568}</bbox> by virtue ofDuckDBStruct.toString()
- Overrides:
registerSqlTypeToClassMappings
in classSQLDialect
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registerClassToSqlMappings
MapsGeometry
types toTypes.OTHER
andStruct
toTypes.STRUCT
Support for struct is limited and results in GeoServer WMS and WFS to interpret it as a String literal. For example, a "bbox"
Struct
attribute value withSQL type name
as STRUCT(xmin FLOAT, xmax FLOAT, ymin FLOAT, ymax FLOAT) will be encoded as <bbox>{xmin=-63.005005, xmax=-63.004997, ymin=-40.81569, ymax=-40.81568}</bbox> by virtue ofDuckDBStruct.toString()
- Overrides:
registerClassToSqlMappings
in classSQLDialect
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encodePostColumnCreateTable
Description copied from class:SQLDialect
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.
- Overrides:
encodePostColumnCreateTable
in classSQLDialect
- Parameters:
att
- The attribute corresponding to the column.
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getGeometrySRID
public Integer getGeometrySRID(String schemaName, String tableName, String columnName, Connection cx) throws SQLException Description copied from class:SQLDialect
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
.- Overrides:
getGeometrySRID
in classSQLDialect
- Parameters:
schemaName
- The database schema, could benull
.tableName
- The table, nevernull
.columnName
- The column name, nevernull
cx
- The database connection.- Throws:
SQLException
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getOptimizedBounds
public List<ReferencedEnvelope> getOptimizedBounds(String schema, SimpleFeatureType featureType, Connection cx) throws SQLException, IOException Description copied from class:SQLDialect
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)- Overrides:
getOptimizedBounds
in classSQLDialect
- Parameters:
schema
- The database schema, if any, or nullfeatureType
- 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
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optimizedBounds
protected ReferencedEnvelope optimizedBounds(SimpleFeatureType featureType, Connection cx) throws SQLException, IOException - Throws:
SQLException
IOException
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encodeGeometryEnvelope
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.- Specified by:
encodeGeometryEnvelope
in classSQLDialect
- See Also:
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decodeGeometryEnvelope
public 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
SQLDialect.encodeGeometryEnvelope(String, String, StringBuffer)
method.This method must not read any other objects from the result set other then the one referenced by column.
- Specified by:
decodeGeometryEnvelope
in classSQLDialect
- Parameters:
rs
- A result setcolumn
- Index into the result set which points at the spatial extent value.cx
- The database connection.- Throws:
SQLException
IOException
- See Also:
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encodeGeometryColumn
public void encodeGeometryColumn(GeometryDescriptor gatt, String prefix, int srid, Hints hints, StringBuffer sql) Description copied from class:SQLDialect
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
, orasWKB
when fetching a geometry.This method must also be sure to properly encode the name of the column with the
SQLDialect.encodeColumnName(String, String, StringBuffer)
function.Example:
sql.append( "asText(" ); column( gatt.getLocalName(), sql ); sql.append( ")" );
- Overrides:
encodeGeometryColumn
in classSQLDialect
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encodeGeometryColumnInternal
protected void encodeGeometryColumnInternal(GeometryDescriptor gatt, String prefix, Hints hints, boolean forceMulti, StringBuffer sql) -
encodeColumnName
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encodeGeometryColumnGeneralized
public void encodeGeometryColumnGeneralized(GeometryDescriptor gatt, String prefix, int srid, StringBuffer sql, Double distance) - Overrides:
encodeGeometryColumnGeneralized
in classSQLDialect
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encodeGeometryColumnSimplified
public void encodeGeometryColumnSimplified(GeometryDescriptor gatt, String prefix, int srid, StringBuffer sql, Double distance) - Overrides:
encodeGeometryColumnSimplified
in classSQLDialect
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decodeGeometryValue
public Geometry decodeGeometryValue(GeometryDescriptor descriptor, ResultSet rs, String column, GeometryFactory factory, Connection cx, Hints hints) throws IOException, SQLException Description copied from class:SQLDialect
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 );
null
values.The factory parameter should be used to instantiate any geometry objects.
- Specified by:
decodeGeometryValue
in classSQLDialect
- Throws:
IOException
SQLException
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parseWKB
- Throws:
SQLException
IOException
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parseWKB
- Throws:
SQLException
IOException
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encodeGeometryValue
public void encodeGeometryValue(Geometry value, int dimension, int srid, StringBuffer sql) throws IOException Description copied from class:BasicSQLDialect
Encodes a geometry value in an sql statement.An implementations should serialize value into some exchange format which will then be transported to the underlying database. For example, consider an implementation which converts a geometry into its well known text representation:
sql.append( "GeomFromText('" ); sql.append( new WKTWriter().write( value ) ); sql.append( ")" );
The srid parameter is the spatial reference system identifier of the geometry, or 0 if not known.
Attention should be paid to emtpy geometries (
g.isEmtpy() == true
) as they cannot be encoded in WKB and several databases fail to handle them property. Common treatment is to equate them to NULL- Specified by:
encodeGeometryValue
in classBasicSQLDialect
- Throws:
IOException
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isConcreteGeometry
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encodePrimaryKey
Description copied from class:SQLDialect
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" );
- Overrides:
encodePrimaryKey
in classSQLDialect
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isLimitOffsetSupported
public boolean isLimitOffsetSupported()Description copied from class:SQLDialect
Returns true if this dialect can encode both Query.getStartIndex() and Query.getMaxFeatures() into native SQL.- Overrides:
isLimitOffsetSupported
in classSQLDialect
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applyLimitOffset
Description copied from class:SQLDialect
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.- Overrides:
applyLimitOffset
in classSQLDialect
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createFilterToSQL
Description copied from class:BasicSQLDialect
Creates the filter encoder to be used by the datastore when encoding query predicates.Sublcasses can override this method to return a subclass of
FilterToSQL
if need be.- Overrides:
createFilterToSQL
in classBasicSQLDialect
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