/*
* Hibernate, Relational Persistence for Idiomatic Java
*
* Copyright (c) 2010, Red Hat Inc. or third-party contributors as
* indicated by the @author tags or express copyright attribution
* statements applied by the authors. All third-party contributions are
* distributed under license by Red Hat Inc.
*
* This copyrighted material is made available to anyone wishing to use, modify,
* copy, or redistribute it subject to the terms and conditions of the GNU
* Lesser General Public License, as published by the Free Software Foundation.
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY
* or FITNESS FOR A PARTICULAR PURPOSE. See the GNU Lesser General Public License
* for more details.
*
* You should have received a copy of the GNU Lesser General Public License
* along with this distribution; if not, write to:
* Free Software Foundation, Inc.
* 51 Franklin Street, Fifth Floor
* Boston, MA 02110-1301 USA
*/
package org.hibernate.dialect;
//import java.io.InputStream;
//import java.io.OutputStream;
//import java.sql.Blob;
import java.sql.CallableStatement;
//import java.sql.Clob;
//import java.sql.NClob;
import java.sql.Connection;
import java.sql.ResultSet;
import java.sql.SQLException;
import java.sql.Types;
import java.util.HashMap;
import java.util.HashSet;
import java.util.Iterator;
import java.util.List;
import java.util.Map;
import java.util.Properties;
import java.util.Set;
import org.hibernate.HibernateException;
import org.hibernate.LockMode;
import org.hibernate.LockOptions;
import org.hibernate.MappingException;
import org.hibernate.NullPrecedence;
import org.hibernate.ScrollMode;
//import org.hibernate.cfg.Environment;
//import org.hibernate.dialect.lock.LockingStrategy;
//import org.hibernate.dialect.lock.OptimisticForceIncrementLockingStrategy;
//import org.hibernate.dialect.lock.OptimisticLockingStrategy;
//import org.hibernate.dialect.lock.PessimisticForceIncrementLockingStrategy;
//import org.hibernate.dialect.lock.PessimisticReadSelectLockingStrategy;
//import org.hibernate.dialect.lock.PessimisticWriteSelectLockingStrategy;
//import org.hibernate.dialect.lock.SelectLockingStrategy;
//import org.hibernate.dialect.pagination.LegacyLimitHandler;
//import org.hibernate.dialect.pagination.LimitHandler;
//import org.hibernate.engine.jdbc.LobCreator;
//import org.hibernate.engine.spi.RowSelection;
//import org.hibernate.engine.spi.SessionImplementor;
//import org.hibernate.exception.spi.ConversionContext;
//import org.hibernate.exception.spi.SQLExceptionConversionDelegate;
//import org.hibernate.exception.spi.SQLExceptionConverter;
//import org.hibernate.exception.spi.ViolatedConstraintNameExtracter;
//import org.hibernate.id.IdentityGenerator;
//import org.hibernate.id.SequenceGenerator;
//import org.hibernate.id.TableHiLoGenerator;
//import org.hibernate.internal.CoreMessageLogger;
import org.hibernate.cfg.AvailableSettings;
import org.hibernate.cfg.Environment;
import org.hibernate.internal.util.ReflectHelper;
import org.hibernate.internal.util.StringHelper;
//import org.hibernate.internal.util.collections.ArrayHelper;
//import org.hibernate.internal.util.io.StreamCopier;
//import org.hibernate.mapping.Column;
//import org.hibernate.metamodel.spi.TypeContributions;
//import org.hibernate.persister.entity.Lockable;
//import org.hibernate.procedure.internal.StandardCallableStatementSupport;
//import org.hibernate.procedure.spi.CallableStatementSupport;
//import org.hibernate.service.ServiceRegistry;
//import org.hibernate.sql.ANSICaseFragment;
//import org.hibernate.sql.ANSIJoinFragment;
//import org.hibernate.sql.CaseFragment;
//import org.hibernate.sql.ForUpdateFragment;
//import org.hibernate.sql.JoinFragment;
//import org.hibernate.type.StandardBasicTypes;
//import org.hibernate.type.descriptor.sql.ClobTypeDescriptor;
//import org.hibernate.type.descriptor.sql.SqlTypeDescriptor;
//import org.jboss.logging.Logger;
/**
* Represents a dialect of SQL implemented by a particular RDBMS. Subclasses implement Hibernate compatibility
* with different systems. Subclasses should provide a public default constructor that register a set of type
* mappings and default Hibernate properties. Subclasses should be immutable.
*
* @author Gavin King, David Channon
*/
@SuppressWarnings("deprecation")
public abstract class Dialect /*implements ConversionContext */ {
// private static final CoreMessageLogger LOG = Logger.getMessageLogger(
// CoreMessageLogger.class,
// Dialect.class.getName()
// );
protected static Map<String, Dialect> driverClass2Dialect = new HashMap<String, Dialect>();
/**
* Defines a default batch size constant
*/
public static final String DEFAULT_BATCH_SIZE = "15";
/**
* Defines a "no batching" batch size constant
*/
public static final String NO_BATCH = "0";
/**
* Characters used as opening for quoting SQL identifiers
*/
public static final String QUOTE = "`\"[";
/**
* Characters used as closing for quoting SQL identifiers
*/
public static final String CLOSED_QUOTE = "`\"]";
private final TypeNames typeNames = new TypeNames();
// private final TypeNames hibernateTypeNames = new TypeNames();
private final Properties properties = new Properties();
// private final Map<String, SQLFunction> sqlFunctions = new HashMap<String, SQLFunction>();
private final Set<String> sqlKeywords = new HashSet<String>();
// constructors and factory methods ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
protected Dialect() {
registerColumnType( Types.BIT, "bit" );
registerColumnType( Types.BOOLEAN, "boolean" );
registerColumnType( Types.TINYINT, "tinyint" );
registerColumnType( Types.SMALLINT, "smallint" );
registerColumnType( Types.INTEGER, "integer" );
registerColumnType( Types.BIGINT, "bigint" );
registerColumnType( Types.FLOAT, "float($p)" );
registerColumnType( Types.DOUBLE, "double precision" );
registerColumnType( Types.NUMERIC, "numeric($p,$s)" );
registerColumnType( Types.REAL, "real" );
registerColumnType( Types.DATE, "date" );
registerColumnType( Types.TIME, "time" );
registerColumnType( Types.TIMESTAMP, "timestamp" );
registerColumnType( Types.VARBINARY, "bit varying($l)" );
registerColumnType( Types.LONGVARBINARY, "bit varying($l)" );
registerColumnType( Types.BLOB, "blob" );
registerColumnType( Types.CHAR, "char($l)" );
registerColumnType( Types.VARCHAR, "varchar($l)" );
registerColumnType( Types.LONGVARCHAR, "varchar($l)" );
registerColumnType( Types.CLOB, "clob" );
registerColumnType( Types.NCHAR, "nchar($l)" );
registerColumnType( Types.NVARCHAR, "nvarchar($l)" );
registerColumnType( Types.LONGNVARCHAR, "nvarchar($l)" );
registerColumnType( Types.NCLOB, "nclob" );
}
/**
* Get an instance of the dialect specified by the current <tt>System</tt> properties.
*
* @return The specified Dialect
* @throws HibernateException If no dialect was specified, or if it could not be instantiated.
*/
public static Dialect getDialect(Connection conn) throws HibernateException {
return instantiateDialect( Environment.getProperties().getProperty( AvailableSettings.DIALECT ) );
}
// /**
// * Get an instance of the dialect specified by the given properties or by
// * the current <tt>System</tt> properties.
// *
// * @param props The properties to use for finding the dialect class to use.
// * @return The specified Dialect
// * @throws HibernateException If no dialect was specified, or if it could not be instantiated.
// */
// public static Dialect getDialect(Properties props) throws HibernateException {
// final String dialectName = props.getProperty( Environment.DIALECT );
// if ( dialectName == null ) {
// return getDialect();
// }
// return instantiateDialect( dialectName );
// }
private static Dialect instantiateDialect(String dialectName) throws HibernateException {
if ( dialectName == null ) {
throw new HibernateException( "The dialect was not set. Set the property hibernate.dialect." );
}
try {
return (Dialect) ReflectHelper.classForName( dialectName ).newInstance();
}
catch ( ClassNotFoundException cnfe ) {
throw new HibernateException( "Dialect class not found: " + dialectName );
}
catch ( Exception e ) {
throw new HibernateException( "Could not instantiate given dialect class: " + dialectName, e );
}
}
/**
* Retrieve a set of default Hibernate properties for this database.
*
* @return a set of Hibernate properties
*/
public final Properties getDefaultProperties() {
return properties;
}
@Override
public String toString() {
return getClass().getName();
}
// database type mapping support ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
// /**
// * Allows the Dialect to contribute additional types
// *
// * @param typeContributions Callback to contribute the types
// * @param serviceRegistry The service registry
// */
// public void contributeTypes(TypeContributions typeContributions, ServiceRegistry serviceRegistry) {
// // by default, nothing to do
// }
/**
* Get the name of the database type associated with the given
* {@link java.sql.Types} typecode.
*
* @param code The {@link java.sql.Types} typecode
* @return the database type name
* @throws HibernateException If no mapping was specified for that type.
*/
public String getTypeName(int code) throws HibernateException {
final String result = typeNames.get( code );
if ( result == null ) {
throw new HibernateException( "No default type mapping for (java.sql.Types) " + code );
}
return result;
}
/**
* Get the name of the database type associated with the given
* {@link java.sql.Types} typecode with the given storage specification
* parameters.
*
* @param code The {@link java.sql.Types} typecode
* @param length The datatype length
* @param precision The datatype precision
* @param scale The datatype scale
* @return the database type name
* @throws HibernateException If no mapping was specified for that type.
*/
public String getTypeName(int code, long length, int precision, int scale) throws HibernateException {
final String result = typeNames.get( code, length, precision, scale );
if ( result == null ) {
throw new HibernateException(
String.format( "No type mapping for java.sql.Types code: %s, length: %s", code, length )
);
}
return result;
}
// /**
// * Get the name of the database type appropriate for casting operations
// * (via the CAST() SQL function) for the given {@link java.sql.Types} typecode.
// *
// * @param code The {@link java.sql.Types} typecode
// * @return The database type name
// */
// public String getCastTypeName(int code) {
// return getTypeName( code, Column.DEFAULT_LENGTH, Column.DEFAULT_PRECISION, Column.DEFAULT_SCALE );
// }
/**
* Return an expression casting the value to the specified type
*
* @param value The value to cast
* @param jdbcTypeCode The JDBC type code to cast to
* @param length The type length
* @param precision The type precision
* @param scale The type scale
*
* @return The cast expression
*/
public String cast(String value, int jdbcTypeCode, int length, int precision, int scale) {
if ( jdbcTypeCode == Types.CHAR ) {
return "cast(" + value + " as char(" + length + "))";
}
else {
return "cast(" + value + "as " + getTypeName( jdbcTypeCode, length, precision, scale ) + ")";
}
}
//
// /**
// * Return an expression casting the value to the specified type. Simply calls
// * {@link #cast(String, int, int, int, int)} passing {@link Column#DEFAULT_PRECISION} and
// * {@link Column#DEFAULT_SCALE} as the precision/scale.
// *
// * @param value The value to cast
// * @param jdbcTypeCode The JDBC type code to cast to
// * @param length The type length
// *
// * @return The cast expression
// */
// public String cast(String value, int jdbcTypeCode, int length) {
// return cast( value, jdbcTypeCode, length, Column.DEFAULT_PRECISION, Column.DEFAULT_SCALE );
// }
// /**
// * Return an expression casting the value to the specified type. Simply calls
// * {@link #cast(String, int, int, int, int)} passing {@link Column#DEFAULT_LENGTH} as the length
// *
// * @param value The value to cast
// * @param jdbcTypeCode The JDBC type code to cast to
// * @param precision The type precision
// * @param scale The type scale
// *
// * @return The cast expression
// */
// public String cast(String value, int jdbcTypeCode, int precision, int scale) {
// return cast( value, jdbcTypeCode, Column.DEFAULT_LENGTH, precision, scale );
// }
/**
* Subclasses register a type name for the given type code and maximum
* column length. <tt>$l</tt> in the type name with be replaced by the
* column length (if appropriate).
*
* @param code The {@link java.sql.Types} typecode
* @param capacity The maximum length of database type
* @param name The database type name
*/
protected void registerColumnType(int code, long capacity, String name) {
typeNames.put( code, capacity, name );
}
/**
* Subclasses register a type name for the given type code. <tt>$l</tt> in
* the type name with be replaced by the column length (if appropriate).
*
* @param code The {@link java.sql.Types} typecode
* @param name The database type name
*/
protected void registerColumnType(int code, String name) {
typeNames.put( code, name );
}
//
// /**
// * Allows the dialect to override a {@link SqlTypeDescriptor}.
// * <p/>
// * If the passed {@code sqlTypeDescriptor} allows itself to be remapped (per
// * {@link org.hibernate.type.descriptor.sql.SqlTypeDescriptor#canBeRemapped()}), then this method uses
// * {@link #getSqlTypeDescriptorOverride} to get an optional override based on the SQL code returned by
// * {@link SqlTypeDescriptor#getSqlType()}.
// * <p/>
// * If this dialect does not provide an override or if the {@code sqlTypeDescriptor} doe not allow itself to be
// * remapped, then this method simply returns the original passed {@code sqlTypeDescriptor}
// *
// * @param sqlTypeDescriptor The {@link SqlTypeDescriptor} to override
// * @return The {@link SqlTypeDescriptor} that should be used for this dialect;
// * if there is no override, then original {@code sqlTypeDescriptor} is returned.
// * @throws IllegalArgumentException if {@code sqlTypeDescriptor} is null.
// *
// * @see #getSqlTypeDescriptorOverride
// */
// public SqlTypeDescriptor remapSqlTypeDescriptor(SqlTypeDescriptor sqlTypeDescriptor) {
// if ( sqlTypeDescriptor == null ) {
// throw new IllegalArgumentException( "sqlTypeDescriptor is null" );
// }
// if ( ! sqlTypeDescriptor.canBeRemapped() ) {
// return sqlTypeDescriptor;
// }
//
// final SqlTypeDescriptor overridden = getSqlTypeDescriptorOverride( sqlTypeDescriptor.getSqlType() );
// return overridden == null ? sqlTypeDescriptor : overridden;
// }
// /**
// * Returns the {@link SqlTypeDescriptor} that should be used to handle the given JDBC type code. Returns
// * {@code null} if there is no override.
// *
// * @param sqlCode A {@link Types} constant indicating the SQL column type
// * @return The {@link SqlTypeDescriptor} to use as an override, or {@code null} if there is no override.
// */
// protected SqlTypeDescriptor getSqlTypeDescriptorOverride(int sqlCode) {
// SqlTypeDescriptor descriptor;
// switch ( sqlCode ) {
// case Types.CLOB: {
// descriptor = useInputStreamToInsertBlob() ? ClobTypeDescriptor.STREAM_BINDING : null;
// break;
// }
// default: {
// descriptor = null;
// break;
// }
// }
// return descriptor;
// }
//
// /**
// * The legacy behavior of Hibernate. LOBs are not processed by merge
// */
// @SuppressWarnings( {"UnusedDeclaration"})
// protected static final LobMergeStrategy LEGACY_LOB_MERGE_STRATEGY = new LobMergeStrategy() {
// @Override
// public Blob mergeBlob(Blob original, Blob target, SessionImplementor session) {
// return target;
// }
//
// @Override
// public Clob mergeClob(Clob original, Clob target, SessionImplementor session) {
// return target;
// }
//
// @Override
// public NClob mergeNClob(NClob original, NClob target, SessionImplementor session) {
// return target;
// }
// };
//
// /**
// * Merge strategy based on transferring contents based on streams.
// */
// @SuppressWarnings( {"UnusedDeclaration"})
// protected static final LobMergeStrategy STREAM_XFER_LOB_MERGE_STRATEGY = new LobMergeStrategy() {
// @Override
// public Blob mergeBlob(Blob original, Blob target, SessionImplementor session) {
// if ( original != target ) {
// try {
// // the BLOB just read during the load phase of merge
// final OutputStream connectedStream = target.setBinaryStream( 1L );
// // the BLOB from the detached state
// final InputStream detachedStream = original.getBinaryStream();
// StreamCopier.copy( detachedStream, connectedStream );
// return target;
// }
// catch (SQLException e ) {
// throw session.getFactory().getSQLExceptionHelper().convert( e, "unable to merge BLOB data" );
// }
// }
// else {
// return NEW_LOCATOR_LOB_MERGE_STRATEGY.mergeBlob( original, target, session );
// }
// }
//
// @Override
// public Clob mergeClob(Clob original, Clob target, SessionImplementor session) {
// if ( original != target ) {
// try {
// // the CLOB just read during the load phase of merge
// final OutputStream connectedStream = target.setAsciiStream( 1L );
// // the CLOB from the detached state
// final InputStream detachedStream = original.getAsciiStream();
// StreamCopier.copy( detachedStream, connectedStream );
// return target;
// }
// catch (SQLException e ) {
// throw session.getFactory().getSQLExceptionHelper().convert( e, "unable to merge CLOB data" );
// }
// }
// else {
// return NEW_LOCATOR_LOB_MERGE_STRATEGY.mergeClob( original, target, session );
// }
// }
//
// @Override
// public NClob mergeNClob(NClob original, NClob target, SessionImplementor session) {
// if ( original != target ) {
// try {
// // the NCLOB just read during the load phase of merge
// final OutputStream connectedStream = target.setAsciiStream( 1L );
// // the NCLOB from the detached state
// final InputStream detachedStream = original.getAsciiStream();
// StreamCopier.copy( detachedStream, connectedStream );
// return target;
// }
// catch (SQLException e ) {
// throw session.getFactory().getSQLExceptionHelper().convert( e, "unable to merge NCLOB data" );
// }
// }
// else {
// return NEW_LOCATOR_LOB_MERGE_STRATEGY.mergeNClob( original, target, session );
// }
// }
// };
//
// /**
// * Merge strategy based on creating a new LOB locator.
// */
// protected static final LobMergeStrategy NEW_LOCATOR_LOB_MERGE_STRATEGY = new LobMergeStrategy() {
// @Override
// public Blob mergeBlob(Blob original, Blob target, SessionImplementor session) {
// if ( original == null && target == null ) {
// return null;
// }
// try {
// final LobCreator lobCreator = session.getFactory().getJdbcServices().getLobCreator( session );
// return original == null
// ? lobCreator.createBlob( ArrayHelper.EMPTY_BYTE_ARRAY )
// : lobCreator.createBlob( original.getBinaryStream(), original.length() );
// }
// catch (SQLException e) {
// throw session.getFactory().getSQLExceptionHelper().convert( e, "unable to merge BLOB data" );
// }
// }
//
// @Override
// public Clob mergeClob(Clob original, Clob target, SessionImplementor session) {
// if ( original == null && target == null ) {
// return null;
// }
// try {
// final LobCreator lobCreator = session.getFactory().getJdbcServices().getLobCreator( session );
// return original == null
// ? lobCreator.createClob( "" )
// : lobCreator.createClob( original.getCharacterStream(), original.length() );
// }
// catch (SQLException e) {
// throw session.getFactory().getSQLExceptionHelper().convert( e, "unable to merge CLOB data" );
// }
// }
//
// @Override
// public NClob mergeNClob(NClob original, NClob target, SessionImplementor session) {
// if ( original == null && target == null ) {
// return null;
// }
// try {
// final LobCreator lobCreator = session.getFactory().getJdbcServices().getLobCreator( session );
// return original == null
// ? lobCreator.createNClob( "" )
// : lobCreator.createNClob( original.getCharacterStream(), original.length() );
// }
// catch (SQLException e) {
// throw session.getFactory().getSQLExceptionHelper().convert( e, "unable to merge NCLOB data" );
// }
// }
// };
//
// public LobMergeStrategy getLobMergeStrategy() {
// return NEW_LOCATOR_LOB_MERGE_STRATEGY;
// }
// // hibernate type mapping support ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
//
// /**
// * Get the name of the Hibernate {@link org.hibernate.type.Type} associated with the given
// * {@link java.sql.Types} type code.
// *
// * @param code The {@link java.sql.Types} type code
// * @return The Hibernate {@link org.hibernate.type.Type} name.
// * @throws HibernateException If no mapping was specified for that type.
// */
// @SuppressWarnings( {"UnusedDeclaration"})
// public String getHibernateTypeName(int code) throws HibernateException {
// final String result = hibernateTypeNames.get( code );
// if ( result == null ) {
// throw new HibernateException( "No Hibernate type mapping for java.sql.Types code: " + code );
// }
// return result;
// }
//
// /**
// * Get the name of the Hibernate {@link org.hibernate.type.Type} associated
// * with the given {@link java.sql.Types} typecode with the given storage
// * specification parameters.
// *
// * @param code The {@link java.sql.Types} typecode
// * @param length The datatype length
// * @param precision The datatype precision
// * @param scale The datatype scale
// * @return The Hibernate {@link org.hibernate.type.Type} name.
// * @throws HibernateException If no mapping was specified for that type.
// */
// public String getHibernateTypeName(int code, int length, int precision, int scale) throws HibernateException {
// final String result = hibernateTypeNames.get( code, length, precision, scale );
// if ( result == null ) {
// throw new HibernateException(
// String.format(
// "No Hibernate type mapping for type [code=%s, length=%s]",
// code,
// length
// )
// );
// }
// return result;
// }
//
// /**
// * Registers a Hibernate {@link org.hibernate.type.Type} name for the given
// * {@link java.sql.Types} type code and maximum column length.
// *
// * @param code The {@link java.sql.Types} typecode
// * @param capacity The maximum length of database type
// * @param name The Hibernate {@link org.hibernate.type.Type} name
// */
// protected void registerHibernateType(int code, long capacity, String name) {
// hibernateTypeNames.put( code, capacity, name);
// }
//
// /**
// * Registers a Hibernate {@link org.hibernate.type.Type} name for the given
// * {@link java.sql.Types} type code.
// *
// * @param code The {@link java.sql.Types} typecode
// * @param name The Hibernate {@link org.hibernate.type.Type} name
// */
// protected void registerHibernateType(int code, String name) {
// hibernateTypeNames.put( code, name);
// }
//
//
// // function support ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
//
// protected void registerFunction(String name, SQLFunction function) {
// // HHH-7721: SQLFunctionRegistry expects all lowercase. Enforce,
// // just in case a user's customer dialect uses mixed cases.
// sqlFunctions.put( name.toLowerCase(), function );
// }
//
// /**
// * Retrieves a map of the dialect's registered functions
// * (functionName => {@link org.hibernate.dialect.function.SQLFunction}).
// *
// * @return The map of registered functions.
// */
// public final Map<String, SQLFunction> getFunctions() {
// return sqlFunctions;
// }
// keyword support ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
protected void registerKeyword(String word) {
sqlKeywords.add( word );
}
public Set<String> getKeywords() {
return sqlKeywords;
}
// native identifier generation ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
//
// /**
// * The class (which implements {@link org.hibernate.id.IdentifierGenerator})
// * which acts as this dialects native generation strategy.
// * <p/>
// * Comes into play whenever the user specifies the native generator.
// *
// * @return The native generator class.
// */
// public Class getNativeIdentifierGeneratorClass() {
// if ( supportsIdentityColumns() ) {
// return IdentityGenerator.class;
// }
// else if ( supportsSequences() ) {
// return SequenceGenerator.class;
// }
// else {
// return TableHiLoGenerator.class;
// }
// }
// IDENTITY support ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
/**
* Does this dialect support identity column key generation?
*
* @return True if IDENTITY columns are supported; false otherwise.
*/
public boolean supportsIdentityColumns() {
return false;
}
/**
* Does the dialect support some form of inserting and selecting
* the generated IDENTITY value all in the same statement.
*
* @return True if the dialect supports selecting the just
* generated IDENTITY in the insert statement.
*/
public boolean supportsInsertSelectIdentity() {
return false;
}
/**
* Whether this dialect have an Identity clause added to the data type or a
* completely separate identity data type
*
* @return boolean
*/
public boolean hasDataTypeInIdentityColumn() {
return true;
}
/**
* Provided we {@link #supportsInsertSelectIdentity}, then attach the
* "select identity" clause to the insert statement.
* <p/>
* Note, if {@link #supportsInsertSelectIdentity} == false then
* the insert-string should be returned without modification.
*
* @param insertString The insert command
* @return The insert command with any necessary identity select
* clause attached.
*/
public String appendIdentitySelectToInsert(String insertString) {
return insertString;
}
/**
* Get the select command to use to retrieve the last generated IDENTITY
* value for a particular table
*
* @param table The table into which the insert was done
* @param column The PK column.
* @param type The {@link java.sql.Types} type code.
* @return The appropriate select command
* @throws MappingException If IDENTITY generation is not supported.
*/
public String getIdentitySelectString(String table, String column, int type) throws MappingException {
return getIdentitySelectString();
}
/**
* Get the select command to use to retrieve the last generated IDENTITY
* value.
*
* @return The appropriate select command
* @throws MappingException If IDENTITY generation is not supported.
*/
protected String getIdentitySelectString() throws MappingException {
throw new MappingException( getClass().getName() + " does not support identity key generation" );
}
/**
* The syntax used during DDL to define a column as being an IDENTITY of
* a particular type.
*
* @param type The {@link java.sql.Types} type code.
* @return The appropriate DDL fragment.
* @throws MappingException If IDENTITY generation is not supported.
*/
public String getIdentityColumnString(int type) throws MappingException {
return getIdentityColumnString();
}
/**
* The syntax used during DDL to define a column as being an IDENTITY.
*
* @return The appropriate DDL fragment.
* @throws MappingException If IDENTITY generation is not supported.
*/
protected String getIdentityColumnString() throws MappingException {
throw new MappingException( getClass().getName() + " does not support identity key generation" );
}
/**
* The keyword used to insert a generated value into an identity column (or null).
* Need if the dialect does not support inserts that specify no column values.
*
* @return The appropriate keyword.
*/
public String getIdentityInsertString() {
return null;
}
// SEQUENCE support ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
/**
* Does this dialect support sequences?
*
* @return True if sequences supported; false otherwise.
*/
public boolean supportsSequences() {
return false;
}
/**
* Does this dialect support "pooled" sequences. Not aware of a better
* name for this. Essentially can we specify the initial and increment values?
*
* @return True if such "pooled" sequences are supported; false otherwise.
* @see #getCreateSequenceStrings(String, int, int)
* @see #getCreateSequenceString(String, int, int)
*/
public boolean supportsPooledSequences() {
return false;
}
/**
* Generate the appropriate select statement to to retrieve the next value
* of a sequence.
* <p/>
* This should be a "stand alone" select statement.
*
* @param sequenceName the name of the sequence
* @return String The "nextval" select string.
* @throws MappingException If sequences are not supported.
*/
public String getSequenceNextValString(String sequenceName) throws MappingException {
throw new MappingException( getClass().getName() + " does not support sequences" );
}
/**
* Generate the select expression fragment that will retrieve the next
* value of a sequence as part of another (typically DML) statement.
* <p/>
* This differs from {@link #getSequenceNextValString(String)} in that this
* should return an expression usable within another statement.
*
* @param sequenceName the name of the sequence
* @return The "nextval" fragment.
* @throws MappingException If sequences are not supported.
*/
public String getSelectSequenceNextValString(String sequenceName) throws MappingException {
throw new MappingException( getClass().getName() + " does not support sequences" );
}
/**
* The multiline script used to create a sequence.
*
* @param sequenceName The name of the sequence
* @return The sequence creation commands
* @throws MappingException If sequences are not supported.
* @deprecated Use {@link #getCreateSequenceString(String, int, int)} instead
*/
@Deprecated
public String[] getCreateSequenceStrings(String sequenceName) throws MappingException {
return new String[] { getCreateSequenceString( sequenceName ) };
}
/**
* An optional multi-line form for databases which {@link #supportsPooledSequences()}.
*
* @param sequenceName The name of the sequence
* @param initialValue The initial value to apply to 'create sequence' statement
* @param incrementSize The increment value to apply to 'create sequence' statement
* @return The sequence creation commands
* @throws MappingException If sequences are not supported.
*/
public String[] getCreateSequenceStrings(String sequenceName, int initialValue, int incrementSize) throws MappingException {
return new String[] { getCreateSequenceString( sequenceName, initialValue, incrementSize ) };
}
/**
* Typically dialects which support sequences can create a sequence
* with a single command. This is convenience form of
* {@link #getCreateSequenceStrings} to help facilitate that.
* <p/>
* Dialects which support sequences and can create a sequence in a
* single command need *only* override this method. Dialects
* which support sequences but require multiple commands to create
* a sequence should instead override {@link #getCreateSequenceStrings}.
*
* @param sequenceName The name of the sequence
* @return The sequence creation command
* @throws MappingException If sequences are not supported.
*/
protected String getCreateSequenceString(String sequenceName) throws MappingException {
throw new MappingException( getClass().getName() + " does not support sequences" );
}
/**
* Overloaded form of {@link #getCreateSequenceString(String)}, additionally
* taking the initial value and increment size to be applied to the sequence
* definition.
* </p>
* The default definition is to suffix {@link #getCreateSequenceString(String)}
* with the string: " start with {initialValue} increment by {incrementSize}" where
* {initialValue} and {incrementSize} are replacement placeholders. Generally
* dialects should only need to override this method if different key phrases
* are used to apply the allocation information.
*
* @param sequenceName The name of the sequence
* @param initialValue The initial value to apply to 'create sequence' statement
* @param incrementSize The increment value to apply to 'create sequence' statement
* @return The sequence creation command
* @throws MappingException If sequences are not supported.
*/
protected String getCreateSequenceString(String sequenceName, int initialValue, int incrementSize) throws MappingException {
if ( supportsPooledSequences() ) {
return getCreateSequenceString( sequenceName ) + " start with " + initialValue + " increment by " + incrementSize;
}
throw new MappingException( getClass().getName() + " does not support pooled sequences" );
}
/**
* The multiline script used to drop a sequence.
*
* @param sequenceName The name of the sequence
* @return The sequence drop commands
* @throws MappingException If sequences are not supported.
*/
public String[] getDropSequenceStrings(String sequenceName) throws MappingException {
return new String[]{getDropSequenceString( sequenceName )};
}
/**
* Typically dialects which support sequences can drop a sequence
* with a single command. This is convenience form of
* {@link #getDropSequenceStrings} to help facilitate that.
* <p/>
* Dialects which support sequences and can drop a sequence in a
* single command need *only* override this method. Dialects
* which support sequences but require multiple commands to drop
* a sequence should instead override {@link #getDropSequenceStrings}.
*
* @param sequenceName The name of the sequence
* @return The sequence drop commands
* @throws MappingException If sequences are not supported.
*/
protected String getDropSequenceString(String sequenceName) throws MappingException {
throw new MappingException( getClass().getName() + " does not support sequences" );
}
/**
* Get the select command used retrieve the names of all sequences.
*
* @return The select command; or null if sequences are not supported.
* @see org.hibernate.tool.hbm2ddl.SchemaUpdate
*/
public String getQuerySequencesString() {
return null;
}
// GUID support ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
/**
* Get the command used to select a GUID from the underlying database.
* <p/>
* Optional operation.
*
* @return The appropriate command.
*/
public String getSelectGUIDString() {
throw new UnsupportedOperationException( getClass().getName() + " does not support GUIDs" );
}
// limit/offset support ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
/**
* Does this dialect support some form of limiting query results
* via a SQL clause?
*
* @return True if this dialect supports some form of LIMIT.
* @deprecated {@link #buildLimitHandler(String, RowSelection)} should be overridden instead.
*/
@Deprecated
public boolean supportsLimit() {
return false;
}
/**
* Does this dialect's LIMIT support (if any) additionally
* support specifying an offset?
*
* @return True if the dialect supports an offset within the limit support.
* @deprecated {@link #buildLimitHandler(String, RowSelection)} should be overridden instead.
*/
@Deprecated
public boolean supportsLimitOffset() {
return supportsLimit();
}
/**
* Does this dialect support bind variables (i.e., prepared statement
* parameters) for its limit/offset?
*
* @return True if bind variables can be used; false otherwise.
* @deprecated {@link #buildLimitHandler(String, RowSelection)} should be overridden instead.
*/
@Deprecated
public boolean supportsVariableLimit() {
return supportsLimit();
}
/**
* ANSI SQL defines the LIMIT clause to be in the form LIMIT offset, limit.
* Does this dialect require us to bind the parameters in reverse order?
*
* @return true if the correct order is limit, offset
* @deprecated {@link #buildLimitHandler(String, RowSelection)} should be overridden instead.
*/
@Deprecated
public boolean bindLimitParametersInReverseOrder() {
return false;
}
/**
* Does the <tt>LIMIT</tt> clause come at the start of the
* <tt>SELECT</tt> statement, rather than at the end?
*
* @return true if limit parameters should come before other parameters
* @deprecated {@link #buildLimitHandler(String, RowSelection)} should be overridden instead.
*/
@Deprecated
public boolean bindLimitParametersFirst() {
return false;
}
/**
* Does the <tt>LIMIT</tt> clause take a "maximum" row number instead
* of a total number of returned rows?
* <p/>
* This is easiest understood via an example. Consider you have a table
* with 20 rows, but you only want to retrieve rows number 11 through 20.
* Generally, a limit with offset would say that the offset = 11 and the
* limit = 10 (we only want 10 rows at a time); this is specifying the
* total number of returned rows. Some dialects require that we instead
* specify offset = 11 and limit = 20, where 20 is the "last" row we want
* relative to offset (i.e. total number of rows = 20 - 11 = 9)
* <p/>
* So essentially, is limit relative from offset? Or is limit absolute?
*
* @return True if limit is relative from offset; false otherwise.
* @deprecated {@link #buildLimitHandler(String, RowSelection)} should be overridden instead.
*/
@Deprecated
public boolean useMaxForLimit() {
return false;
}
/**
* Generally, if there is no limit applied to a Hibernate query we do not apply any limits
* to the SQL query. This option forces that the limit be written to the SQL query.
*
* @return True to force limit into SQL query even if none specified in Hibernate query; false otherwise.
* @deprecated {@link #buildLimitHandler(String, RowSelection)} should be overridden instead.
*/
@Deprecated
public boolean forceLimitUsage() {
return false;
}
/**
* Given a limit and an offset, apply the limit clause to the query.
*
* @param query The query to which to apply the limit.
* @param offset The offset of the limit
* @param limit The limit of the limit ;)
* @return The modified query statement with the limit applied.
* @deprecated {@link #buildLimitHandler(String, RowSelection)} should be overridden instead.
*/
@Deprecated
public String getLimitString(String query, int offset, int limit) {
return getLimitString( query, ( offset > 0 || forceLimitUsage() ) );
}
/**
* Apply s limit clause to the query.
* <p/>
* Typically dialects utilize {@link #supportsVariableLimit() variable}
* limit clauses when they support limits. Thus, when building the
* select command we do not actually need to know the limit or the offest
* since we will just be using placeholders.
* <p/>
* Here we do still pass along whether or not an offset was specified
* so that dialects not supporting offsets can generate proper exceptions.
* In general, dialects will override one or the other of this method and
* {@link #getLimitString(String, int, int)}.
*
* @param query The query to which to apply the limit.
* @param hasOffset Is the query requesting an offset?
* @return the modified SQL
* @deprecated {@link #buildLimitHandler(String, RowSelection)} should be overridden instead.
*/
@Deprecated
protected String getLimitString(String query, boolean hasOffset) {
throw new UnsupportedOperationException( "Paged queries not supported by " + getClass().getName());
}
/**
* Hibernate APIs explicitly state that setFirstResult() should be a zero-based offset. Here we allow the
* Dialect a chance to convert that value based on what the underlying db or driver will expect.
* <p/>
* NOTE: what gets passed into {@link #getLimitString(String,int,int)} is the zero-based offset. Dialects which
* do not {@link #supportsVariableLimit} should take care to perform any needed first-row-conversion calls prior
* to injecting the limit values into the SQL string.
*
* @param zeroBasedFirstResult The user-supplied, zero-based first row offset.
* @return The corresponding db/dialect specific offset.
* @see org.hibernate.Query#setFirstResult
* @see org.hibernate.Criteria#setFirstResult
* @deprecated {@link #buildLimitHandler(String, RowSelection)} should be overridden instead.
*/
@Deprecated
public int convertToFirstRowValue(int zeroBasedFirstResult) {
return zeroBasedFirstResult;
}
// /**
// * Build delegate managing LIMIT clause.
// *
// * @param sql SQL query.
// * @param selection Selection criteria. {@code null} in case of unlimited number of rows.
// * @return LIMIT clause delegate.
// */
// public LimitHandler buildLimitHandler(String sql, RowSelection selection) {
// return new LegacyLimitHandler( this, sql, selection );
// }
// lock acquisition support ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
/**
* Informational metadata about whether this dialect is known to support
* specifying timeouts for requested lock acquisitions.
*
* @return True is this dialect supports specifying lock timeouts.
*/
public boolean supportsLockTimeouts() {
return true;
}
/**
* If this dialect supports specifying lock timeouts, are those timeouts
* rendered into the <tt>SQL</tt> string as parameters. The implication
* is that Hibernate will need to bind the timeout value as a parameter
* in the {@link java.sql.PreparedStatement}. If true, the param position
* is always handled as the last parameter; if the dialect specifies the
* lock timeout elsewhere in the <tt>SQL</tt> statement then the timeout
* value should be directly rendered into the statement and this method
* should return false.
*
* @return True if the lock timeout is rendered into the <tt>SQL</tt>
* string as a parameter; false otherwise.
*/
public boolean isLockTimeoutParameterized() {
return false;
}
// /**
// * Get a strategy instance which knows how to acquire a database-level lock
// * of the specified mode for this dialect.
// *
// * @param lockable The persister for the entity to be locked.
// * @param lockMode The type of lock to be acquired.
// * @return The appropriate locking strategy.
// * @since 3.2
// */
// public LockingStrategy getLockingStrategy(Lockable lockable, LockMode lockMode) {
// switch ( lockMode ) {
// case PESSIMISTIC_FORCE_INCREMENT:
// return new PessimisticForceIncrementLockingStrategy( lockable, lockMode );
// case PESSIMISTIC_WRITE:
// return new PessimisticWriteSelectLockingStrategy( lockable, lockMode );
// case PESSIMISTIC_READ:
// return new PessimisticReadSelectLockingStrategy( lockable, lockMode );
// case OPTIMISTIC:
// return new OptimisticLockingStrategy( lockable, lockMode );
// case OPTIMISTIC_FORCE_INCREMENT:
// return new OptimisticForceIncrementLockingStrategy( lockable, lockMode );
// default:
// return new SelectLockingStrategy( lockable, lockMode );
// }
// }
/**
* Given LockOptions (lockMode, timeout), determine the appropriate for update fragment to use.
*
* @param lockOptions contains the lock mode to apply.
* @return The appropriate for update fragment.
*/
public String getForUpdateString(LockOptions lockOptions) {
final LockMode lockMode = lockOptions.getLockMode();
return getForUpdateString( lockMode, lockOptions.getTimeOut() );
}
@SuppressWarnings( {"deprecation"})
private String getForUpdateString(LockMode lockMode, int timeout){
switch ( lockMode ) {
case UPGRADE:
return getForUpdateString();
case PESSIMISTIC_READ:
return getReadLockString( timeout );
case PESSIMISTIC_WRITE:
return getWriteLockString( timeout );
case UPGRADE_NOWAIT:
case FORCE:
case PESSIMISTIC_FORCE_INCREMENT:
return getForUpdateNowaitString();
case UPGRADE_SKIPLOCKED:
return getForUpdateSkipLockedString();
default:
return "";
}
}
/**
* Given a lock mode, determine the appropriate for update fragment to use.
*
* @param lockMode The lock mode to apply.
* @return The appropriate for update fragment.
*/
public String getForUpdateString(LockMode lockMode) {
return getForUpdateString( lockMode, LockOptions.WAIT_FOREVER );
}
/**
* Get the string to append to SELECT statements to acquire locks
* for this dialect.
*
* @return The appropriate <tt>FOR UPDATE</tt> clause string.
*/
public String getForUpdateString() {
return " for update";
}
/**
* Get the string to append to SELECT statements to acquire WRITE locks
* for this dialect. Location of the of the returned string is treated
* the same as getForUpdateString.
*
* @param timeout in milliseconds, -1 for indefinite wait and 0 for no wait.
* @return The appropriate <tt>LOCK</tt> clause string.
*/
public String getWriteLockString(int timeout) {
return getForUpdateString();
}
/**
* Get the string to append to SELECT statements to acquire WRITE locks
* for this dialect. Location of the of the returned string is treated
* the same as getForUpdateString.
*
* @param timeout in milliseconds, -1 for indefinite wait and 0 for no wait.
* @return The appropriate <tt>LOCK</tt> clause string.
*/
public String getReadLockString(int timeout) {
return getForUpdateString();
}
/**
* Is <tt>FOR UPDATE OF</tt> syntax supported?
*
* @return True if the database supports <tt>FOR UPDATE OF</tt> syntax;
* false otherwise.
*/
public boolean forUpdateOfColumns() {
// by default we report no support
return false;
}
/**
* Does this dialect support <tt>FOR UPDATE</tt> in conjunction with
* outer joined rows?
*
* @return True if outer joined rows can be locked via <tt>FOR UPDATE</tt>.
*/
public boolean supportsOuterJoinForUpdate() {
return true;
}
/**
* Get the <tt>FOR UPDATE OF column_list</tt> fragment appropriate for this
* dialect given the aliases of the columns to be write locked.
*
* @param aliases The columns to be write locked.
* @return The appropriate <tt>FOR UPDATE OF column_list</tt> clause string.
*/
public String getForUpdateString(String aliases) {
// by default we simply return the getForUpdateString() result since
// the default is to say no support for "FOR UPDATE OF ..."
return getForUpdateString();
}
/**
* Get the <tt>FOR UPDATE OF column_list</tt> fragment appropriate for this
* dialect given the aliases of the columns to be write locked.
*
* @param aliases The columns to be write locked.
* @param lockOptions the lock options to apply
* @return The appropriate <tt>FOR UPDATE OF column_list</tt> clause string.
*/
@SuppressWarnings({"unchecked", "UnusedParameters"})
public String getForUpdateString(String aliases, LockOptions lockOptions) {
LockMode lockMode = lockOptions.getLockMode();
final Iterator<Map.Entry<String, LockMode>> itr = lockOptions.getAliasLockIterator();
while ( itr.hasNext() ) {
// seek the highest lock mode
final Map.Entry<String, LockMode>entry = itr.next();
final LockMode lm = entry.getValue();
if ( lm.greaterThan( lockMode ) ) {
lockMode = lm;
}
}
lockOptions.setLockMode( lockMode );
return getForUpdateString( lockOptions );
}
/**
* Retrieves the <tt>FOR UPDATE NOWAIT</tt> syntax specific to this dialect.
*
* @return The appropriate <tt>FOR UPDATE NOWAIT</tt> clause string.
*/
public String getForUpdateNowaitString() {
// by default we report no support for NOWAIT lock semantics
return getForUpdateString();
}
/**
* Retrieves the <tt>FOR UPDATE SKIP LOCKED</tt> syntax specific to this dialect.
*
* @return The appropriate <tt>FOR UPDATE SKIP LOCKED</tt> clause string.
*/
public String getForUpdateSkipLockedString() {
// by default we report no support for SKIP_LOCKED lock semantics
return getForUpdateString();
}
/**
* Get the <tt>FOR UPDATE OF column_list NOWAIT</tt> fragment appropriate
* for this dialect given the aliases of the columns to be write locked.
*
* @param aliases The columns to be write locked.
* @return The appropriate <tt>FOR UPDATE OF colunm_list NOWAIT</tt> clause string.
*/
public String getForUpdateNowaitString(String aliases) {
return getForUpdateString( aliases );
}
/**
* Get the <tt>FOR UPDATE OF column_list SKIP LOCKED</tt> fragment appropriate
* for this dialect given the aliases of the columns to be write locked.
*
* @param aliases The columns to be write locked.
* @return The appropriate <tt>FOR UPDATE colunm_list SKIP LOCKED</tt> clause string.
*/
public String getForUpdateSkipLockedString(String aliases) {
return getForUpdateString( aliases );
}
/**
* Some dialects support an alternative means to <tt>SELECT FOR UPDATE</tt>,
* whereby a "lock hint" is appends to the table name in the from clause.
* <p/>
* contributed by <a href="http://sourceforge.net/users/heschulz">Helge Schulz</a>
*
* @param mode The lock mode to apply
* @param tableName The name of the table to which to apply the lock hint.
* @return The table with any required lock hints.
* @deprecated use {@code appendLockHint(LockOptions,String)} instead
*/
@Deprecated
public String appendLockHint(LockMode mode, String tableName) {
return appendLockHint( new LockOptions( mode ), tableName );
}
/**
* Some dialects support an alternative means to <tt>SELECT FOR UPDATE</tt>,
* whereby a "lock hint" is appends to the table name in the from clause.
* <p/>
* contributed by <a href="http://sourceforge.net/users/heschulz">Helge Schulz</a>
*
* @param lockOptions The lock options to apply
* @param tableName The name of the table to which to apply the lock hint.
* @return The table with any required lock hints.
*/
public String appendLockHint(LockOptions lockOptions, String tableName){
return tableName;
}
//
// /**
// * Modifies the given SQL by applying the appropriate updates for the specified
// * lock modes and key columns.
// * <p/>
// * The behavior here is that of an ANSI SQL <tt>SELECT FOR UPDATE</tt>. This
// * method is really intended to allow dialects which do not support
// * <tt>SELECT FOR UPDATE</tt> to achieve this in their own fashion.
// *
// * @param sql the SQL string to modify
// * @param aliasedLockOptions lock options indexed by aliased table names.
// * @param keyColumnNames a map of key columns indexed by aliased table names.
// * @return the modified SQL string.
// */
// public String applyLocksToSql(String sql, LockOptions aliasedLockOptions, Map<String, String[]> keyColumnNames) {
// return sql + new ForUpdateFragment( this, aliasedLockOptions, keyColumnNames ).toFragmentString();
// }
// table support ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
/**
* Command used to create a table.
*
* @return The command used to create a table.
*/
public String getCreateTableString() {
return "create table";
}
/**
* Slight variation on {@link #getCreateTableString}. Here, we have the
* command used to create a table when there is no primary key and
* duplicate rows are expected.
* <p/>
* Most databases do not care about the distinction; originally added for
* Teradata support which does care.
*
* @return The command used to create a multiset table.
*/
public String getCreateMultisetTableString() {
return getCreateTableString();
}
// temporary table support ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
/**
* Does this dialect support temporary tables?
*
* @return True if temp tables are supported; false otherwise.
*/
public boolean supportsTemporaryTables() {
return false;
}
/**
* Generate a temporary table name given the base table.
*
* @param baseTableName The table name from which to base the temp table name.
* @return The generated temp table name.
*/
public String generateTemporaryTableName(String baseTableName) {
return "HT_" + baseTableName;
}
/**
* Command used to create a temporary table.
*
* @return The command used to create a temporary table.
*/
public String getCreateTemporaryTableString() {
return "create table";
}
/**
* Get any fragments needing to be postfixed to the command for
* temporary table creation.
*
* @return Any required postfix.
*/
public String getCreateTemporaryTablePostfix() {
return "";
}
/**
* Command used to drop a temporary table.
*
* @return The command used to drop a temporary table.
*/
public String getDropTemporaryTableString() {
return "drop table";
}
/**
* Does the dialect require that temporary table DDL statements occur in
* isolation from other statements? This would be the case if the creation
* would cause any current transaction to get committed implicitly.
* <p/>
* JDBC defines a standard way to query for this information via the
* {@link java.sql.DatabaseMetaData#dataDefinitionCausesTransactionCommit()}
* method. However, that does not distinguish between temporary table
* DDL and other forms of DDL; MySQL, for example, reports DDL causing a
* transaction commit via its driver, even though that is not the case for
* temporary table DDL.
* <p/>
* Possible return values and their meanings:<ul>
* <li>{@link Boolean#TRUE} - Unequivocally, perform the temporary table DDL
* in isolation.</li>
* <li>{@link Boolean#FALSE} - Unequivocally, do <b>not</b> perform the
* temporary table DDL in isolation.</li>
* <li><i>null</i> - defer to the JDBC driver response in regards to
* {@link java.sql.DatabaseMetaData#dataDefinitionCausesTransactionCommit()}</li>
* </ul>
*
* @return see the result matrix above.
*/
public Boolean performTemporaryTableDDLInIsolation() {
return null;
}
/**
* Do we need to drop the temporary table after use?
*
* @return True if the table should be dropped.
*/
public boolean dropTemporaryTableAfterUse() {
return true;
}
// callable statement support ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
/**
* Registers a parameter (either OUT, or the new REF_CURSOR param type available in Java 8) capable of
* returning {@link java.sql.ResultSet} *by position*. Pre-Java 8, registering such ResultSet-returning
* parameters varied greatly across database and drivers; hence its inclusion as part of the Dialect contract.
*
* @param statement The callable statement.
* @param position The bind position at which to register the output param.
*
* @return The number of (contiguous) bind positions used.
*
* @throws SQLException Indicates problems registering the param.
*/
public int registerResultSetOutParameter(CallableStatement statement, int position) throws SQLException {
throw new UnsupportedOperationException(
getClass().getName() +
" does not support resultsets via stored procedures"
);
}
/**
* Registers a parameter (either OUT, or the new REF_CURSOR param type available in Java 8) capable of
* returning {@link java.sql.ResultSet} *by name*. Pre-Java 8, registering such ResultSet-returning
* parameters varied greatly across database and drivers; hence its inclusion as part of the Dialect contract.
*
* @param statement The callable statement.
* @param name The parameter name (for drivers which support named parameters).
*
* @return The number of (contiguous) bind positions used.
*
* @throws SQLException Indicates problems registering the param.
*/
@SuppressWarnings("UnusedParameters")
public int registerResultSetOutParameter(CallableStatement statement, String name) throws SQLException {
throw new UnsupportedOperationException(
getClass().getName() +
" does not support resultsets via stored procedures"
);
}
/**
* Given a callable statement previously processed by {@link #registerResultSetOutParameter},
* extract the {@link java.sql.ResultSet} from the OUT parameter.
*
* @param statement The callable statement.
* @return The extracted result set.
* @throws SQLException Indicates problems extracting the result set.
*/
public ResultSet getResultSet(CallableStatement statement) throws SQLException {
throw new UnsupportedOperationException(
getClass().getName() + " does not support resultsets via stored procedures"
);
}
/**
* Given a callable statement previously processed by {@link #registerResultSetOutParameter},
* extract the {@link java.sql.ResultSet}.
*
* @param statement The callable statement.
* @param position The bind position at which to register the output param.
*
* @return The extracted result set.
*
* @throws SQLException Indicates problems extracting the result set.
*/
@SuppressWarnings("UnusedParameters")
public ResultSet getResultSet(CallableStatement statement, int position) throws SQLException {
throw new UnsupportedOperationException(
getClass().getName() + " does not support resultsets via stored procedures"
);
}
/**
* Given a callable statement previously processed by {@link #registerResultSetOutParameter},
* extract the {@link java.sql.ResultSet} from the OUT parameter.
*
* @param statement The callable statement.
* @param name The parameter name (for drivers which support named parameters).
*
* @return The extracted result set.
*
* @throws SQLException Indicates problems extracting the result set.
*/
@SuppressWarnings("UnusedParameters")
public ResultSet getResultSet(CallableStatement statement, String name) throws SQLException {
throw new UnsupportedOperationException(
getClass().getName() + " does not support resultsets via stored procedures"
);
}
// current timestamp support ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
/**
* Does this dialect support a way to retrieve the database's current
* timestamp value?
*
* @return True if the current timestamp can be retrieved; false otherwise.
*/
public boolean supportsCurrentTimestampSelection() {
return false;
}
/**
* Should the value returned by {@link #getCurrentTimestampSelectString}
* be treated as callable. Typically this indicates that JDBC escape
* syntax is being used...
*
* @return True if the {@link #getCurrentTimestampSelectString} return
* is callable; false otherwise.
*/
public boolean isCurrentTimestampSelectStringCallable() {
throw new UnsupportedOperationException( "Database not known to define a current timestamp function" );
}
/**
* Retrieve the command used to retrieve the current timestamp from the
* database.
*
* @return The command.
*/
public String getCurrentTimestampSelectString() {
throw new UnsupportedOperationException( "Database not known to define a current timestamp function" );
}
/**
* The name of the database-specific SQL function for retrieving the
* current timestamp.
*
* @return The function name.
*/
public String getCurrentTimestampSQLFunctionName() {
// the standard SQL function name is current_timestamp...
return "current_timestamp";
}
//
// /**
// * Build an instance of a {@link SQLExceptionConversionDelegate} for
// * interpreting dialect-specific error or SQLState codes.
// * <p/>
// * When {@link #buildSQLExceptionConverter} returns null, the default
// * {@link SQLExceptionConverter} is used to interpret SQLState and
// * error codes. If this method is overridden to return a non-null value,
// * the default {@link SQLExceptionConverter} will use the returned
// * {@link SQLExceptionConversionDelegate} in addition to the following
// * standard delegates:
// * <ol>
// * <li>a "static" delegate based on the JDBC 4 defined SQLException hierarchy;</li>
// * <li>a delegate that interprets SQLState codes for either X/Open or SQL-2003 codes,
// * depending on java.sql.DatabaseMetaData#getSQLStateType</li>
// * </ol>
// * <p/>
// * It is strongly recommended that specific Dialect implementations override this
// * method, since interpretation of a SQL error is much more accurate when based on
// * the a vendor-specific ErrorCode rather than the SQLState.
// * <p/>
// * Specific Dialects may override to return whatever is most appropriate for that vendor.
// *
// * @return The SQLExceptionConversionDelegate for this dialect
// */
// public SQLExceptionConversionDelegate buildSQLExceptionConversionDelegate() {
// return null;
// }
//
// private static final ViolatedConstraintNameExtracter EXTRACTER = new ViolatedConstraintNameExtracter() {
// public String extractConstraintName(SQLException sqle) {
// return null;
// }
// };
//
// public ViolatedConstraintNameExtracter getViolatedConstraintNameExtracter() {
// return EXTRACTER;
// }
// union subclass support ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
/**
* Given a {@link java.sql.Types} type code, determine an appropriate
* null value to use in a select clause.
* <p/>
* One thing to consider here is that certain databases might
* require proper casting for the nulls here since the select here
* will be part of a UNION/UNION ALL.
*
* @param sqlType The {@link java.sql.Types} type code.
* @return The appropriate select clause value fragment.
*/
public String getSelectClauseNullString(int sqlType) {
return "null";
}
/**
* Does this dialect support UNION ALL, which is generally a faster
* variant of UNION?
*
* @return True if UNION ALL is supported; false otherwise.
*/
public boolean supportsUnionAll() {
return false;
}
// miscellaneous support ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
//
// /**
// * Create a {@link org.hibernate.sql.JoinFragment} strategy responsible
// * for handling this dialect's variations in how joins are handled.
// *
// * @return This dialect's {@link org.hibernate.sql.JoinFragment} strategy.
// */
// public JoinFragment createOuterJoinFragment() {
// return new ANSIJoinFragment();
// }
//
// /**
// * Create a {@link org.hibernate.sql.CaseFragment} strategy responsible
// * for handling this dialect's variations in how CASE statements are
// * handled.
// *
// * @return This dialect's {@link org.hibernate.sql.CaseFragment} strategy.
// */
// public CaseFragment createCaseFragment() {
// return new ANSICaseFragment();
// }
/**
* The fragment used to insert a row without specifying any column values.
* This is not possible on some databases.
*
* @return The appropriate empty values clause.
*/
public String getNoColumnsInsertString() {
return "values ( )";
}
/**
* The name of the SQL function that transforms a string to
* lowercase
*
* @return The dialect-specific lowercase function.
*/
public String getLowercaseFunction() {
return "lower";
}
/**
* The name of the SQL function that can do case insensitive <b>like</b> comparison.
*
* @return The dialect-specific "case insensitive" like function.
*/
public String getCaseInsensitiveLike(){
return "like";
}
/**
* Does this dialect support case insensitive LIKE restrictions?
*
* @return {@code true} if the underlying database supports case insensitive like comparison,
* {@code false} otherwise. The default is {@code false}.
*/
public boolean supportsCaseInsensitiveLike(){
return false;
}
/**
* Meant as a means for end users to affect the select strings being sent
* to the database and perhaps manipulate them in some fashion.
* <p/>
* The recommend approach is to instead use
* {@link org.hibernate.Interceptor#onPrepareStatement(String)}.
*
* @param select The select command
* @return The mutated select command, or the same as was passed in.
*/
public String transformSelectString(String select) {
return select;
}
/**
* What is the maximum length Hibernate can use for generated aliases?
* <p/>
* The maximum here should account for the fact that Hibernate often needs to append "uniqueing" information
* to the end of generated aliases. That "uniqueing" information will be added to the end of a identifier
* generated to the length specified here; so be sure to leave some room (generally speaking 5 positions will
* suffice).
*
* @return The maximum length.
*/
public int getMaxAliasLength() {
return 10;
}
/**
* The SQL literal value to which this database maps boolean values.
*
* @param bool The boolean value
* @return The appropriate SQL literal.
*/
public String toBooleanValueString(boolean bool) {
return bool ? "1" : "0";
}
// identifier quoting support ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
/**
* The character specific to this dialect used to begin a quoted identifier.
*
* @return The dialect's specific open quote character.
*/
public char openQuote() {
return '"';
}
/**
* The character specific to this dialect used to close a quoted identifier.
*
* @return The dialect's specific close quote character.
*/
public char closeQuote() {
return '"';
}
/**
* Apply dialect-specific quoting.
* <p/>
* By default, the incoming value is checked to see if its first character
* is the back-tick (`). If so, the dialect specific quoting is applied.
*
* @param name The value to be quoted.
* @return The quoted (or unmodified, if not starting with back-tick) value.
* @see #openQuote()
* @see #closeQuote()
*/
public final String quote(String name) {
if ( name == null ) {
return null;
}
if ( name.charAt( 0 ) == '`' ) {
return openQuote() + name.substring( 1, name.length() - 1 ) + closeQuote();
}
else {
return name;
}
}
// DDL support ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
/**
* Get the SQL command used to create the named schema
*
* @param schemaName The name of the schema to be created.
*
* @return The creation command
*/
public String getCreateSchemaCommand(String schemaName) {
return "create schema " + schemaName;
}
/**
* Get the SQL command used to drop the named schema
*
* @param schemaName The name of the schema to be dropped.
*
* @return The drop command
*/
public String getDropSchemaCommand(String schemaName) {
return "drop schema " + schemaName;
}
/**
* Does this dialect support the <tt>ALTER TABLE</tt> syntax?
*
* @return True if we support altering of tables; false otherwise.
*/
public boolean hasAlterTable() {
return true;
}
/**
* Do we need to drop constraints before dropping tables in this dialect?
*
* @return True if constraints must be dropped prior to dropping
* the table; false otherwise.
*/
public boolean dropConstraints() {
return true;
}
/**
* Do we need to qualify index names with the schema name?
*
* @return boolean
*/
public boolean qualifyIndexName() {
return true;
}
/**
* The syntax used to add a column to a table (optional).
*
* @return The "add column" fragment.
*/
public String getAddColumnString() {
throw new UnsupportedOperationException( "No add column syntax supported by " + getClass().getName() );
}
/**
* The syntax for the suffix used to add a column to a table (optional).
*
* @return The suffix "add column" fragment.
*/
public String getAddColumnSuffixString() {
return "";
}
public String getDropForeignKeyString() {
return " drop constraint ";
}
public String getTableTypeString() {
// grrr... for differentiation of mysql storage engines
return "";
}
/**
* The syntax used to add a foreign key constraint to a table.
*
* @param constraintName The FK constraint name.
* @param foreignKey The names of the columns comprising the FK
* @param referencedTable The table referenced by the FK
* @param primaryKey The explicit columns in the referencedTable referenced
* by this FK.
* @param referencesPrimaryKey if false, constraint should be
* explicit about which column names the constraint refers to
*
* @return the "add FK" fragment
*/
public String getAddForeignKeyConstraintString(
String constraintName,
String[] foreignKey,
String referencedTable,
String[] primaryKey,
boolean referencesPrimaryKey) {
final StringBuilder res = new StringBuilder( 30 );
res.append( " add constraint " )
.append( quote( constraintName ) )
.append( " foreign key (" )
.append( StringHelper.join( ", ", foreignKey ) )
.append( ") references " )
.append( referencedTable );
if ( !referencesPrimaryKey ) {
res.append( " (" )
.append( StringHelper.join( ", ", primaryKey ) )
.append( ')' );
}
return res.toString();
}
/**
* The syntax used to add a primary key constraint to a table.
*
* @param constraintName The name of the PK constraint.
* @return The "add PK" fragment
*/
public String getAddPrimaryKeyConstraintString(String constraintName) {
return " add constraint " + constraintName + " primary key ";
}
/**
* Does the database/driver have bug in deleting rows that refer to other rows being deleted in the same query?
*
* @return {@code true} if the database/driver has this bug
*/
public boolean hasSelfReferentialForeignKeyBug() {
return false;
}
/**
* The keyword used to specify a nullable column.
*
* @return String
*/
public String getNullColumnString() {
return "";
}
/**
* Does this dialect/database support commenting on tables, columns, etc?
*
* @return {@code true} if commenting is supported
*/
public boolean supportsCommentOn() {
return false;
}
/**
* Get the comment into a form supported for table definition.
*
* @param comment The comment to apply
*
* @return The comment fragment
*/
public String getTableComment(String comment) {
return "";
}
/**
* Get the comment into a form supported for column definition.
*
* @param comment The comment to apply
*
* @return The comment fragment
*/
public String getColumnComment(String comment) {
return "";
}
/**
* For dropping a table, can the phrase "if exists" be applied before the table name?
* <p/>
* NOTE : Only one or the other (or neither) of this and {@link #supportsIfExistsAfterTableName} should return true
*
* @return {@code true} if the "if exists" can be applied before the table name
*/
public boolean supportsIfExistsBeforeTableName() {
return false;
}
/**
* For dropping a table, can the phrase "if exists" be applied after the table name?
* <p/>
* NOTE : Only one or the other (or neither) of this and {@link #supportsIfExistsBeforeTableName} should return true
*
* @return {@code true} if the "if exists" can be applied after the table name
*/
public boolean supportsIfExistsAfterTableName() {
return false;
}
/**
* For dropping a constraint with an "alter table", can the phrase "if exists" be applied before the constraint name?
* <p/>
* NOTE : Only one or the other (or neither) of this and {@link #supportsIfExistsAfterConstraintName} should return true
*
* @return {@code true} if the "if exists" can be applied before the constraint name
*/
public boolean supportsIfExistsBeforeConstraintName() {
return false;
}
/**
* For dropping a constraint with an "alter table", can the phrase "if exists" be applied after the constraint name?
* <p/>
* NOTE : Only one or the other (or neither) of this and {@link #supportsIfExistsBeforeConstraintName} should return true
*
* @return {@code true} if the "if exists" can be applied after the constraint name
*/
public boolean supportsIfExistsAfterConstraintName() {
return false;
}
/**
* Generate a DROP TABLE statement
*
* @param tableName The name of the table to drop
*
* @return The DROP TABLE command
*/
public String getDropTableString(String tableName) {
final StringBuilder buf = new StringBuilder( "drop table " );
if ( supportsIfExistsBeforeTableName() ) {
buf.append( "if exists " );
}
buf.append( tableName ).append( getCascadeConstraintsString() );
if ( supportsIfExistsAfterTableName() ) {
buf.append( " if exists" );
}
return buf.toString();
}
/**
* Does this dialect support column-level check constraints?
*
* @return True if column-level CHECK constraints are supported; false
* otherwise.
*/
public boolean supportsColumnCheck() {
return true;
}
/**
* Does this dialect support table-level check constraints?
*
* @return True if table-level CHECK constraints are supported; false
* otherwise.
*/
public boolean supportsTableCheck() {
return true;
}
/**
* Does this dialect support cascaded delete on foreign key definitions?
*
* @return {@code true} indicates that the dialect does support cascaded delete on foreign keys.
*/
public boolean supportsCascadeDelete() {
return true;
}
/**
* Completely optional cascading drop clause
*
* @return String
*/
public String getCascadeConstraintsString() {
return "";
}
/**
* Returns the separator to use for defining cross joins when translating HQL queries.
* <p/>
* Typically this will be either [<tt> cross join </tt>] or [<tt>, </tt>]
* <p/>
* Note that the spaces are important!
*
* @return The cross join separator
*/
public String getCrossJoinSeparator() {
return " cross join ";
}
public ColumnAliasExtractor getColumnAliasExtractor() {
return ColumnAliasExtractor.COLUMN_LABEL_EXTRACTOR;
}
// Informational metadata ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
/**
* Does this dialect support empty IN lists?
* <p/>
* For example, is [where XYZ in ()] a supported construct?
*
* @return True if empty in lists are supported; false otherwise.
* @since 3.2
*/
public boolean supportsEmptyInList() {
return true;
}
/**
* Are string comparisons implicitly case insensitive.
* <p/>
* In other words, does [where 'XYZ' = 'xyz'] resolve to true?
*
* @return True if comparisons are case insensitive.
* @since 3.2
*/
public boolean areStringComparisonsCaseInsensitive() {
return false;
}
/**
* Is this dialect known to support what ANSI-SQL terms "row value
* constructor" syntax; sometimes called tuple syntax.
* <p/>
* Basically, does it support syntax like
* "... where (FIRST_NAME, LAST_NAME) = ('Steve', 'Ebersole') ...".
*
* @return True if this SQL dialect is known to support "row value
* constructor" syntax; false otherwise.
* @since 3.2
*/
public boolean supportsRowValueConstructorSyntax() {
// return false here, as most databases do not properly support this construct...
return false;
}
/**
* If the dialect supports {@link #supportsRowValueConstructorSyntax() row values},
* does it offer such support in IN lists as well?
* <p/>
* For example, "... where (FIRST_NAME, LAST_NAME) IN ( (?, ?), (?, ?) ) ..."
*
* @return True if this SQL dialect is known to support "row value
* constructor" syntax in the IN list; false otherwise.
* @since 3.2
*/
public boolean supportsRowValueConstructorSyntaxInInList() {
return false;
}
/**
* Should LOBs (both BLOB and CLOB) be bound using stream operations (i.e.
* {@link java.sql.PreparedStatement#setBinaryStream}).
*
* @return True if BLOBs and CLOBs should be bound using stream operations.
* @since 3.2
*/
public boolean useInputStreamToInsertBlob() {
return true;
}
/**
* Does this dialect support parameters within the <tt>SELECT</tt> clause of
* <tt>INSERT ... SELECT ...</tt> statements?
*
* @return True if this is supported; false otherwise.
* @since 3.2
*/
public boolean supportsParametersInInsertSelect() {
return true;
}
/**
* Does this dialect require that references to result variables
* (i.e, select expresssion aliases) in an ORDER BY clause be
* replaced by column positions (1-origin) as defined
* by the select clause?
* @return true if result variable references in the ORDER BY
* clause should be replaced by column positions;
* false otherwise.
*/
public boolean replaceResultVariableInOrderByClauseWithPosition() {
return false;
}
/**
* Renders an ordering fragment
*
* @param expression The SQL order expression. In case of {@code @OrderBy} annotation user receives property placeholder
* (e.g. attribute name enclosed in '{' and '}' signs).
* @param collation Collation string in format {@code collate IDENTIFIER}, or {@code null}
* if expression has not been explicitly specified.
* @param order Order direction. Possible values: {@code asc}, {@code desc}, or {@code null}
* if expression has not been explicitly specified.
* @param nulls Nulls precedence. Default value: {@link NullPrecedence#NONE}.
* @return Renders single element of {@code ORDER BY} clause.
*/
public String renderOrderByElement(String expression, String collation, String order, NullPrecedence nulls) {
final StringBuilder orderByElement = new StringBuilder( expression );
if ( collation != null ) {
orderByElement.append( " " ).append( collation );
}
if ( order != null ) {
orderByElement.append( " " ).append( order );
}
if ( nulls != NullPrecedence.NONE ) {
orderByElement.append( " nulls " ).append( nulls.name().toLowerCase() );
}
return orderByElement.toString();
}
/**
* Does this dialect require that parameters appearing in the <tt>SELECT</tt> clause be wrapped in <tt>cast()</tt>
* calls to tell the db parser the expected type.
*
* @return True if select clause parameter must be cast()ed
* @since 3.2
*/
public boolean requiresCastingOfParametersInSelectClause() {
return false;
}
/**
* Does this dialect support asking the result set its positioning
* information on forward only cursors. Specifically, in the case of
* scrolling fetches, Hibernate needs to use
* {@link java.sql.ResultSet#isAfterLast} and
* {@link java.sql.ResultSet#isBeforeFirst}. Certain drivers do not
* allow access to these methods for forward only cursors.
* <p/>
* NOTE : this is highly driver dependent!
*
* @return True if methods like {@link java.sql.ResultSet#isAfterLast} and
* {@link java.sql.ResultSet#isBeforeFirst} are supported for forward
* only cursors; false otherwise.
* @since 3.2
*/
public boolean supportsResultSetPositionQueryMethodsOnForwardOnlyCursor() {
return true;
}
/**
* Does this dialect support definition of cascade delete constraints
* which can cause circular chains?
*
* @return True if circular cascade delete constraints are supported; false
* otherwise.
* @since 3.2
*/
public boolean supportsCircularCascadeDeleteConstraints() {
return true;
}
/**
* Are subselects supported as the left-hand-side (LHS) of
* IN-predicates.
* <p/>
* In other words, is syntax like "... <subquery> IN (1, 2, 3) ..." supported?
*
* @return True if subselects can appear as the LHS of an in-predicate;
* false otherwise.
* @since 3.2
*/
public boolean supportsSubselectAsInPredicateLHS() {
return true;
}
/**
* Expected LOB usage pattern is such that I can perform an insert
* via prepared statement with a parameter binding for a LOB value
* without crazy casting to JDBC driver implementation-specific classes...
* <p/>
* Part of the trickiness here is the fact that this is largely
* driver dependent. For example, Oracle (which is notoriously bad with
* LOB support in their drivers historically) actually does a pretty good
* job with LOB support as of the 10.2.x versions of their drivers...
*
* @return True if normal LOB usage patterns can be used with this driver;
* false if driver-specific hookiness needs to be applied.
* @since 3.2
*/
public boolean supportsExpectedLobUsagePattern() {
return true;
}
/**
* Does the dialect support propagating changes to LOB
* values back to the database? Talking about mutating the
* internal value of the locator as opposed to supplying a new
* locator instance...
* <p/>
* For BLOBs, the internal value might be changed by:
* {@link java.sql.Blob#setBinaryStream},
* {@link java.sql.Blob#setBytes(long, byte[])},
* {@link java.sql.Blob#setBytes(long, byte[], int, int)},
* or {@link java.sql.Blob#truncate(long)}.
* <p/>
* For CLOBs, the internal value might be changed by:
* {@link java.sql.Clob#setAsciiStream(long)},
* {@link java.sql.Clob#setCharacterStream(long)},
* {@link java.sql.Clob#setString(long, String)},
* {@link java.sql.Clob#setString(long, String, int, int)},
* or {@link java.sql.Clob#truncate(long)}.
* <p/>
* NOTE : I do not know the correct answer currently for
* databases which (1) are not part of the cruise control process
* or (2) do not {@link #supportsExpectedLobUsagePattern}.
*
* @return True if the changes are propagated back to the
* database; false otherwise.
* @since 3.2
*/
public boolean supportsLobValueChangePropogation() {
// todo : pretty sure this is the same as the java.sql.DatabaseMetaData.locatorsUpdateCopy method added in JDBC 4, see HHH-6046
return true;
}
/**
* Is it supported to materialize a LOB locator outside the transaction in
* which it was created?
* <p/>
* Again, part of the trickiness here is the fact that this is largely
* driver dependent.
* <p/>
* NOTE: all database I have tested which {@link #supportsExpectedLobUsagePattern()}
* also support the ability to materialize a LOB outside the owning transaction...
*
* @return True if unbounded materialization is supported; false otherwise.
* @since 3.2
*/
public boolean supportsUnboundedLobLocatorMaterialization() {
return true;
}
/**
* Does this dialect support referencing the table being mutated in
* a subquery. The "table being mutated" is the table referenced in
* an UPDATE or a DELETE query. And so can that table then be
* referenced in a subquery of said UPDATE/DELETE query.
* <p/>
* For example, would the following two syntaxes be supported:<ul>
* <li>delete from TABLE_A where ID not in ( select ID from TABLE_A )</li>
* <li>update TABLE_A set NON_ID = 'something' where ID in ( select ID from TABLE_A)</li>
* </ul>
*
* @return True if this dialect allows references the mutating table from
* a subquery.
*/
public boolean supportsSubqueryOnMutatingTable() {
return true;
}
/**
* Does the dialect support an exists statement in the select clause?
*
* @return True if exists checks are allowed in the select clause; false otherwise.
*/
public boolean supportsExistsInSelect() {
return true;
}
/**
* For the underlying database, is READ_COMMITTED isolation implemented by
* forcing readers to wait for write locks to be released?
*
* @return True if writers block readers to achieve READ_COMMITTED; false otherwise.
*/
public boolean doesReadCommittedCauseWritersToBlockReaders() {
return false;
}
/**
* For the underlying database, is REPEATABLE_READ isolation implemented by
* forcing writers to wait for read locks to be released?
*
* @return True if readers block writers to achieve REPEATABLE_READ; false otherwise.
*/
public boolean doesRepeatableReadCauseReadersToBlockWriters() {
return false;
}
/**
* Does this dialect support using a JDBC bind parameter as an argument
* to a function or procedure call?
*
* @return Returns {@code true} if the database supports accepting bind params as args, {@code false} otherwise. The
* default is {@code true}.
*/
@SuppressWarnings( {"UnusedDeclaration"})
public boolean supportsBindAsCallableArgument() {
return true;
}
/**
* Does this dialect support `count(a,b)`?
*
* @return True if the database supports counting tuples; false otherwise.
*/
public boolean supportsTupleCounts() {
return false;
}
/**
* Does this dialect support `count(distinct a,b)`?
*
* @return True if the database supports counting distinct tuples; false otherwise.
*/
public boolean supportsTupleDistinctCounts() {
// oddly most database in fact seem to, so true is the default.
return true;
}
/**
* Return the limit that the underlying database places on the number elements in an {@code IN} predicate.
* If the database defines no such limits, simply return zero or less-than-zero.
*
* @return int The limit, or zero-or-less to indicate no limit.
*/
public int getInExpressionCountLimit() {
return 0;
}
/**
* HHH-4635
* Oracle expects all Lob values to be last in inserts and updates.
*
* @return boolean True of Lob values should be last, false if it
* does not matter.
*/
public boolean forceLobAsLastValue() {
return false;
}
/**
* Some dialects have trouble applying pessimistic locking depending upon what other query options are
* specified (paging, ordering, etc). This method allows these dialects to request that locking be applied
* by subsequent selects.
*
* @return {@code true} indicates that the dialect requests that locking be applied by subsequent select;
* {@code false} (the default) indicates that locking should be applied to the main SQL statement..
*/
public boolean useFollowOnLocking() {
return false;
}
/**
* Negate an expression
*
* @param expression The expression to negate
*
* @return The negated expression
*/
public String getNotExpression(String expression) {
return "not " + expression;
}
/**
* Does this dialect support the <tt>UNIQUE</tt> column syntax?
*
* @return boolean
*
* @deprecated {@link #getUniqueDelegate()} should be overridden instead.
*/
@Deprecated
public boolean supportsUnique() {
return true;
}
/**
* Does this dialect support adding Unique constraints via create and alter table ?
*
* @return boolean
*
* @deprecated {@link #getUniqueDelegate()} should be overridden instead.
*/
@Deprecated
public boolean supportsUniqueConstraintInCreateAlterTable() {
return true;
}
/**
* The syntax used to add a unique constraint to a table.
*
* @param constraintName The name of the unique constraint.
* @return The "add unique" fragment
*
* @deprecated {@link #getUniqueDelegate()} should be overridden instead.
*/
@Deprecated
public String getAddUniqueConstraintString(String constraintName) {
return " add constraint " + constraintName + " unique ";
}
/**
* Is the combination of not-null and unique supported?
*
* @return deprecated
*
* @deprecated {@link #getUniqueDelegate()} should be overridden instead.
*/
@Deprecated
public boolean supportsNotNullUnique() {
return true;
}
/**
* Apply a hint to the query. The entire query is provided, allowing the Dialect full control over the placement
* and syntax of the hint. By default, ignore the hint and simply return the query.
*
* @param query The query to which to apply the hint.
* @param hints The hints to apply
* @return The modified SQL
*/
public String getQueryHintString(String query, List<String> hints) {
return query;
}
/**
* Certain dialects support a subset of ScrollModes. Provide a default to be used by Criteria and Query.
*
* @return ScrollMode
*/
public ScrollMode defaultScrollMode() {
return ScrollMode.SCROLL_INSENSITIVE;
}
/**
* Does this dialect support tuples in subqueries? Ex:
* delete from Table1 where (col1, col2) in (select col1, col2 from Table2)
*
* @return boolean
*/
public boolean supportsTuplesInSubqueries() {
return true;
}
//
// public CallableStatementSupport getCallableStatementSupport() {
// // most databases do not support returning cursors (ref_cursor)...
// return StandardCallableStatementSupport.NO_REF_CURSOR_INSTANCE;
// }
}