org.hibernate.dialect
Class HSQLDialect

java.lang.Object
  org.hibernate.dialect.Dialect
      org.hibernate.dialect.HSQLDialect

public class HSQLDialect
extends Dialect

An SQL dialect compatible with HSQLDB (HyperSQL).

Note this version supports HSQLDB version 1.8 and higher, only.

Enhancements to version 3.5.0 GA to provide basic support for both HSQLDB 1.8.x and 2.0 Should work with Hibernate 3.2 and later

Author:

Christoph Sturm, Phillip Baird, Fred Toussi

Nested Class Summary

static class

HSQLDialect.ReadUncommittedLockingStrategy

Field Summary

Fields inherited from class org.hibernate.dialect.Dialect

CLOSED_QUOTE, DEFAULT_BATCH_SIZE, NO_BATCH, QUOTE

Constructor Summary

HSQLDialect()

Method Summary

boolean	bindLimitParametersFirst() Does the LIMIT clause come at the start of the SELECT statement, rather than at the end?
boolean	doesReadCommittedCauseWritersToBlockReaders() For the underlying database, is READ_COMMITTED isolation implemented by forcing readers to wait for write locks to be released?
boolean	doesRepeatableReadCauseReadersToBlockWriters() For the underlying database, is REPEATABLE_READ isolation implemented by forcing writers to wait for read locks to be released?
boolean	dropTemporaryTableAfterUse() Do we need to drop the temporary table after use? todo - clarify usage by Hibernate Version 1.8 GLOBAL TEMPORARY table definitions persist beyond the end of the session (data is cleared).
String	generateTemporaryTableName(String baseTableName) With HSQLDB 2.0, the table name is qualified with MODULE to assist the drop statement (in-case there is a global name beginning with HT_)
String	getAddColumnString() The syntax used to add a column to a table (optional).
protected String	getCreateSequenceString(String sequenceName) Typically dialects which support sequences can create a sequence with a single command.
String	getCreateTemporaryTablePostfix() No fragment is needed if data is not needed beyond commit, otherwise should add "on commit preserve rows"
String	getCreateTemporaryTableString() Command used to create a temporary table.
String	getCurrentTimestampSelectString() Retrieve the command used to retrieve the current timestamp from the database.
String	getCurrentTimestampSQLFunctionName() The name of the database-specific SQL function for retrieving the current timestamp.
protected String	getDropSequenceString(String sequenceName) Typically dialects which support sequences can drop a sequence with a single command.
String	getDropTemporaryTableString() Command used to drop a temporary table.
String	getForUpdateString() Get the string to append to SELECT statements to acquire locks for this dialect.
String	getIdentityColumnString() The syntax used during DDL to define a column as being an IDENTITY.
String	getIdentityInsertString() The keyword used to insert a generated value into an identity column (or null).
String	getIdentitySelectString() Get the select command to use to retrieve the last generated IDENTITY value.
String	getLimitString(String sql, boolean hasOffset) Apply s limit clause to the query.
LockingStrategy	getLockingStrategy(Lockable lockable, LockMode lockMode) For HSQLDB 2.0, this is a copy of the base class implementation.
String	getQuerySequencesString() Get the select command used retrieve the names of all sequences.
String	getSelectClauseNullString(int sqlType) Given a Types type code, determine an appropriate null value to use in a select clause.
String	getSelectSequenceNextValString(String sequenceName) Generate the select expression fragment that will retrieve the next value of a sequence as part of another (typically DML) statement.
String	getSequenceNextValString(String sequenceName) Generate the appropriate select statement to to retrieve the next value of a sequence.
ViolatedConstraintNameExtracter	getViolatedConstraintNameExtracter()
boolean	isCurrentTimestampSelectStringCallable() Should the value returned by getCurrentTimestampSelectString() be treated as callable.
Boolean	performTemporaryTableDDLInIsolation() Different behaviour for GLOBAL TEMPORARY (1.8) and LOCAL TEMPORARY (2.0) Possible return values and their meanings: Boolean.TRUE - Unequivocally, perform the temporary table DDL in isolation. Boolean.FALSE - Unequivocally, do not perform the temporary table DDL in isolation. null - defer to the JDBC driver response in regards to DatabaseMetaData.dataDefinitionCausesTransactionCommit()
boolean	requiresCastingOfParametersInSelectClause() todo - needs usage clarification If the SELECT statement is always part of a UNION, then the type of parameter is resolved by v.
boolean	supportsColumnCheck() Does this dialect support column-level check constraints?
boolean	supportsCommentOn()
boolean	supportsCurrentTimestampSelection() HSQLDB 1.8.x requires CALL CURRENT_TIMESTAMP but this should not be treated as a callable statement.
boolean	supportsEmptyInList() Does this dialect support empty IN lists? For example, is [where XYZ in ()] a supported construct?
boolean	supportsIdentityColumns() Does this dialect support identity column key generation?
boolean	supportsIfExistsAfterTableName()
boolean	supportsLimit() Does this dialect support some form of limiting query results via a SQL clause?
boolean	supportsLobValueChangePropogation() Does the dialect support propogating 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...
boolean	supportsLockTimeouts() Informational metadata about whether this dialect is known to support specifying timeouts for requested lock acquisitions.
boolean	supportsPooledSequences() Does this dialect support "pooled" sequences.
boolean	supportsSequences() Does this dialect support sequences?
boolean	supportsTemporaryTables() Does this dialect support temporary tables?
boolean	supportsTupleDistinctCounts() Does this dialect support `count(distinct a,b)`?
boolean	supportsUnionAll() Does this dialect support UNION ALL, which is generally a faster variant of UNION?
boolean	supportsUnique() Does this dialect support the UNIQUE column syntax?
String	toBooleanValueString(boolean bool) The SQL literal value to which this database maps boolean values.

Methods inherited from class org.hibernate.dialect.Dialect

appendIdentitySelectToInsert, appendLockHint, applyLocksToSql, areStringComparisonsCaseInsensitive, bindLimitParametersInReverseOrder, buildSQLExceptionConverter, closeQuote, convertToFirstRowValue, createCaseFragment, createOuterJoinFragment, dropConstraints, forceLimitUsage, forUpdateOfColumns, getAddForeignKeyConstraintString, getAddPrimaryKeyConstraintString, getCascadeConstraintsString, getCastTypeName, getColumnComment, getCreateMultisetTableString, getCreateSequenceString, getCreateSequenceStrings, getCreateSequenceStrings, getCreateTableString, getCrossJoinSeparator, getDefaultProperties, getDialect, getDialect, getDropForeignKeyString, getDropSequenceStrings, getForUpdateNowaitString, getForUpdateNowaitString, getForUpdateString, getForUpdateString, getForUpdateString, getForUpdateString, getFunctions, getHibernateTypeName, getHibernateTypeName, getIdentityColumnString, getIdentitySelectString, getKeywords, getLimitString, getLowercaseFunction, getMaxAliasLength, getNativeIdentifierGeneratorClass, getNoColumnsInsertString, getNullColumnString, getReadLockString, getResultSet, getSelectGUIDString, getTableComment, getTableTypeString, getTypeName, getTypeName, getWriteLockString, hasAlterTable, hasDataTypeInIdentityColumn, hasSelfReferentialForeignKeyBug, isLockTimeoutParameterized, openQuote, qualifyIndexName, quote, registerColumnType, registerColumnType, registerFunction, registerHibernateType, registerHibernateType, registerKeyword, registerResultSetOutParameter, supportsBindAsCallableArgument, supportsCascadeDelete, supportsCircularCascadeDeleteConstraints, supportsExistsInSelect, supportsExpectedLobUsagePattern, supportsIfExistsBeforeTableName, supportsInsertSelectIdentity, supportsLimitOffset, supportsNotNullUnique, supportsOuterJoinForUpdate, supportsParametersInInsertSelect, supportsResultSetPositionQueryMethodsOnForwardOnlyCursor, supportsRowValueConstructorSyntax, supportsRowValueConstructorSyntaxInInList, supportsSubqueryOnMutatingTable, supportsSubselectAsInPredicateLHS, supportsTableCheck, supportsTupleCounts, supportsUnboundedLobLocatorMaterialization, supportsUniqueConstraintInCreateAlterTable, supportsVariableLimit, toString, transformSelectString, useInputStreamToInsertBlob, useMaxForLimit

Methods inherited from class java.lang.Object

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

Constructor Detail

HSQLDialect

public HSQLDialect()

Method Detail

getAddColumnString

public String getAddColumnString()

Description copied from class: Dialect

The syntax used to add a column to a table (optional).

Overrides:

getAddColumnString in class Dialect

Returns:

The "add column" fragment.

supportsIdentityColumns

public boolean supportsIdentityColumns()

Description copied from class: Dialect

Does this dialect support identity column key generation?

Overrides:

supportsIdentityColumns in class Dialect

Returns:

True if IDENTITY columns are supported; false otherwise.

getIdentityColumnString

public String getIdentityColumnString()

Description copied from class: Dialect

The syntax used during DDL to define a column as being an IDENTITY.

Overrides:

getIdentityColumnString in class Dialect

Returns:

The appropriate DDL fragment.

getIdentitySelectString

public String getIdentitySelectString()

Description copied from class: Dialect

Get the select command to use to retrieve the last generated IDENTITY value.

Overrides:

getIdentitySelectString in class Dialect

Returns:

The appropriate select command

getIdentityInsertString

public String getIdentityInsertString()

Description copied from class: Dialect

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.

Overrides:

getIdentityInsertString in class Dialect

Returns:

The appropriate keyword.

supportsLockTimeouts

public boolean supportsLockTimeouts()

Description copied from class: Dialect

Informational metadata about whether this dialect is known to support specifying timeouts for requested lock acquisitions.

Overrides:

supportsLockTimeouts in class Dialect

Returns:

True is this dialect supports specifying lock timeouts.

getForUpdateString

public String getForUpdateString()

Description copied from class: Dialect

Get the string to append to SELECT statements to acquire locks for this dialect.

Overrides:

getForUpdateString in class Dialect

Returns:

The appropriate FOR UPDATE clause string.

supportsUnique

public boolean supportsUnique()

Description copied from class: Dialect

Does this dialect support the UNIQUE column syntax?

Overrides:

supportsUnique in class Dialect

Returns:

boolean

supportsLimit

public boolean supportsLimit()

Description copied from class: Dialect

Does this dialect support some form of limiting query results via a SQL clause?

Overrides:

supportsLimit in class Dialect

Returns:

True if this dialect supports some form of LIMIT.

getLimitString

public String getLimitString(String sql,
                             boolean hasOffset)

Description copied from class: Dialect

Apply s limit clause to the query.

Typically dialects utilize 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.

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 Dialect.getLimitString(String, int, int).

Overrides:

getLimitString in class Dialect

Parameters:

sql - The query to which to apply the limit.

hasOffset - Is the query requesting an offset?

Returns:

the modified SQL

bindLimitParametersFirst

public boolean bindLimitParametersFirst()

Description copied from class: Dialect

Does the LIMIT clause come at the start of the SELECT statement, rather than at the end?

Overrides:

bindLimitParametersFirst in class Dialect

Returns:

true if limit parameters should come before other parameters

supportsIfExistsAfterTableName

public boolean supportsIfExistsAfterTableName()

Overrides:

supportsIfExistsAfterTableName in class Dialect

supportsColumnCheck

public boolean supportsColumnCheck()

Description copied from class: Dialect

Does this dialect support column-level check constraints?

Overrides:

supportsColumnCheck in class Dialect

Returns:

True if column-level CHECK constraints are supported; false otherwise.

supportsSequences

public boolean supportsSequences()

Description copied from class: Dialect

Does this dialect support sequences?

Overrides:

supportsSequences in class Dialect

Returns:

True if sequences supported; false otherwise.

supportsPooledSequences

public boolean supportsPooledSequences()

Description copied from class: Dialect

Does this dialect support "pooled" sequences. Not aware of a better name for this. Essentially can we specify the initial and increment values?

Overrides:

supportsPooledSequences in class Dialect

Returns:

True if such "pooled" sequences are supported; false otherwise.

See Also:

Dialect.getCreateSequenceStrings(String, int, int), Dialect.getCreateSequenceString(String, int, int)

getCreateSequenceString

protected String getCreateSequenceString(String sequenceName)

Description copied from class: Dialect

Typically dialects which support sequences can create a sequence with a single command. This is convenience form of Dialect.getCreateSequenceStrings(java.lang.String) to help facilitate that.

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 Dialect.getCreateSequenceStrings(java.lang.String).

Overrides:

getCreateSequenceString in class Dialect

Parameters:

sequenceName - The name of the sequence

Returns:

The sequence creation command

getDropSequenceString

protected String getDropSequenceString(String sequenceName)

Description copied from class: Dialect

Typically dialects which support sequences can drop a sequence with a single command. This is convenience form of Dialect.getDropSequenceStrings(java.lang.String) to help facilitate that.

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 Dialect.getDropSequenceStrings(java.lang.String).

Overrides:

getDropSequenceString in class Dialect

Parameters:

sequenceName - The name of the sequence

Returns:

The sequence drop commands

getSelectSequenceNextValString

public String getSelectSequenceNextValString(String sequenceName)

Description copied from class: Dialect

Generate the select expression fragment that will retrieve the next value of a sequence as part of another (typically DML) statement.

This differs from Dialect.getSequenceNextValString(String) in that this should return an expression usable within another statement.

Overrides:

getSelectSequenceNextValString in class Dialect

Parameters:

sequenceName - the name of the sequence

Returns:

The "nextval" fragment.

getSequenceNextValString

public String getSequenceNextValString(String sequenceName)

Description copied from class: Dialect

Generate the appropriate select statement to to retrieve the next value of a sequence.

This should be a "stand alone" select statement.

Overrides:

getSequenceNextValString in class Dialect

Parameters:

sequenceName - the name of the sequence

Returns:

String The "nextval" select string.

getQuerySequencesString

public String getQuerySequencesString()

Description copied from class: Dialect

Get the select command used retrieve the names of all sequences.

Overrides:

getQuerySequencesString in class Dialect

Returns:

The select command; or null if sequences are not supported.

See Also:

SchemaUpdate

getViolatedConstraintNameExtracter

public ViolatedConstraintNameExtracter getViolatedConstraintNameExtracter()

Overrides:

getViolatedConstraintNameExtracter in class Dialect

getSelectClauseNullString

public String getSelectClauseNullString(int sqlType)

Description copied from class: Dialect

Given a Types type code, determine an appropriate null value to use in a select clause.

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.

Overrides:

getSelectClauseNullString in class Dialect

Parameters:

sqlType - The Types type code.

Returns:

The appropriate select clause value fragment.

supportsUnionAll

public boolean supportsUnionAll()

Description copied from class: Dialect

Does this dialect support UNION ALL, which is generally a faster variant of UNION?

Overrides:

supportsUnionAll in class Dialect

Returns:

True if UNION ALL is supported; false otherwise.

supportsTemporaryTables

public boolean supportsTemporaryTables()

Does this dialect support temporary tables?

Overrides:

supportsTemporaryTables in class Dialect

Returns:

True if temp tables are supported; false otherwise.

generateTemporaryTableName

public String generateTemporaryTableName(String baseTableName)

With HSQLDB 2.0, the table name is qualified with MODULE to assist the drop statement (in-case there is a global name beginning with HT_)

Overrides:

generateTemporaryTableName in class Dialect

Parameters:

baseTableName - The table name from which to base the temp table name.

Returns:

The generated temp table name.

getCreateTemporaryTableString

public String getCreateTemporaryTableString()

Command used to create a temporary table.

Overrides:

getCreateTemporaryTableString in class Dialect

Returns:

The command used to create a temporary table.

getCreateTemporaryTablePostfix

public String getCreateTemporaryTablePostfix()

No fragment is needed if data is not needed beyond commit, otherwise should add "on commit preserve rows"

Overrides:

getCreateTemporaryTablePostfix in class Dialect

Returns:

Any required postfix.

getDropTemporaryTableString

public String getDropTemporaryTableString()

Command used to drop a temporary table.

Overrides:

getDropTemporaryTableString in class Dialect

Returns:

The command used to drop a temporary table.

performTemporaryTableDDLInIsolation

public Boolean performTemporaryTableDDLInIsolation()

Different behaviour for GLOBAL TEMPORARY (1.8) and LOCAL TEMPORARY (2.0)

Possible return values and their meanings:

• Boolean.TRUE - Unequivocally, perform the temporary table DDL in isolation.
• Boolean.FALSE - Unequivocally, do not perform the temporary table DDL in isolation.
• null - defer to the JDBC driver response in regards to DatabaseMetaData.dataDefinitionCausesTransactionCommit()

Overrides:

performTemporaryTableDDLInIsolation in class Dialect

Returns:

see the result matrix above.

dropTemporaryTableAfterUse

public boolean dropTemporaryTableAfterUse()

Do we need to drop the temporary table after use? todo - clarify usage by Hibernate Version 1.8 GLOBAL TEMPORARY table definitions persist beyond the end of the session (data is cleared). If there are not too many such tables, perhaps we can avoid dropping them and reuse the table next time?

Overrides:

dropTemporaryTableAfterUse in class Dialect

Returns:

True if the table should be dropped.

supportsCurrentTimestampSelection

public boolean supportsCurrentTimestampSelection()

HSQLDB 1.8.x requires CALL CURRENT_TIMESTAMP but this should not be treated as a callable statement. It is equivalent to "select current_timestamp from dual" in some databases. HSQLDB 2.0 also supports VALUES CURRENT_TIMESTAMP

Overrides:

supportsCurrentTimestampSelection in class Dialect

Returns:

True if the current timestamp can be retrieved; false otherwise.

isCurrentTimestampSelectStringCallable

public boolean isCurrentTimestampSelectStringCallable()

Should the value returned by getCurrentTimestampSelectString() be treated as callable. Typically this indicates that JDBC escape syntax is being used...

Overrides:

isCurrentTimestampSelectStringCallable in class Dialect

Returns:

True if the getCurrentTimestampSelectString() return is callable; false otherwise.

getCurrentTimestampSelectString

public String getCurrentTimestampSelectString()

Retrieve the command used to retrieve the current timestamp from the database.

Overrides:

getCurrentTimestampSelectString in class Dialect

Returns:

The command.

getCurrentTimestampSQLFunctionName

public String getCurrentTimestampSQLFunctionName()

The name of the database-specific SQL function for retrieving the current timestamp.

Overrides:

getCurrentTimestampSQLFunctionName in class Dialect

Returns:

The function name.

getLockingStrategy

public LockingStrategy getLockingStrategy(Lockable lockable,
                                          LockMode lockMode)

For HSQLDB 2.0, this is a copy of the base class implementation. For HSQLDB 1.8, only READ_UNCOMMITTED is supported.

Overrides:

getLockingStrategy in class Dialect

Parameters:

lockable - The persister for the entity to be locked.

lockMode - The type of lock to be acquired.

Returns:

The appropriate locking strategy.

Since:

3.2

supportsCommentOn

public boolean supportsCommentOn()

Overrides:

supportsCommentOn in class Dialect

supportsEmptyInList

public boolean supportsEmptyInList()

Description copied from class: Dialect

Does this dialect support empty IN lists?

For example, is [where XYZ in ()] a supported construct?

Overrides:

supportsEmptyInList in class Dialect

Returns:

True if empty in lists are supported; false otherwise.

requiresCastingOfParametersInSelectClause

public boolean requiresCastingOfParametersInSelectClause()

todo - needs usage clarification If the SELECT statement is always part of a UNION, then the type of parameter is resolved by v. 2.0, but not v. 1.8 (assuming the other SELECT in the UNION has a column reference in the same position and can be type-resolved). On the other hand if the SELECT statement is isolated, all versions of HSQLDB require casting for "select ? from .." to work.

Overrides:

requiresCastingOfParametersInSelectClause in class Dialect

Returns:

True if select clause parameter must be cast()ed

Since:

3.2

doesReadCommittedCauseWritersToBlockReaders

public boolean doesReadCommittedCauseWritersToBlockReaders()

For the underlying database, is READ_COMMITTED isolation implemented by forcing readers to wait for write locks to be released?

Overrides:

doesReadCommittedCauseWritersToBlockReaders in class Dialect

Returns:

True if writers block readers to achieve READ_COMMITTED; false otherwise.

doesRepeatableReadCauseReadersToBlockWriters

public boolean doesRepeatableReadCauseReadersToBlockWriters()

For the underlying database, is REPEATABLE_READ isolation implemented by forcing writers to wait for read locks to be released?

Overrides:

doesRepeatableReadCauseReadersToBlockWriters in class Dialect

Returns:

True if readers block writers to achieve REPEATABLE_READ; false otherwise.

supportsLobValueChangePropogation

public boolean supportsLobValueChangePropogation()

Description copied from class: Dialect

Does the dialect support propogating 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...

For BLOBs, the internal value might be changed by: Blob.setBinaryStream(long), Blob.setBytes(long, byte[]), Blob.setBytes(long, byte[], int, int), or Blob.truncate(long).

For CLOBs, the internal value might be changed by: Clob.setAsciiStream(long), Clob.setCharacterStream(long), Clob.setString(long, String), Clob.setString(long, String, int, int), or Clob.truncate(long).

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 Dialect.supportsExpectedLobUsagePattern().

Overrides:

supportsLobValueChangePropogation in class Dialect

Returns:

True if the changes are propogated back to the database; false otherwise.

toBooleanValueString

public String toBooleanValueString(boolean bool)

Description copied from class: Dialect

The SQL literal value to which this database maps boolean values.

Overrides:

toBooleanValueString in class Dialect

Parameters:

bool - The boolean value

Returns:

The appropriate SQL literal.

supportsTupleDistinctCounts

public boolean supportsTupleDistinctCounts()

Description copied from class: Dialect

Does this dialect support `count(distinct a,b)`?

Overrides:

supportsTupleDistinctCounts in class Dialect

Returns:

True if the database supports counting disintct tuples; false otherwise.