OpenJPA can take advantage of any JDBC 2.x compliant driver, making almost any major database a candidate for use. See our officially supported database list in Appendix 2, Supported Databases for more information. Typically, OpenJPA auto-configures its JDBC behavior and SQL dialect for your database, based on the values of your connection-related configuration properties.
If OpenJPA cannot detect what type of database you are using, or if you are
using an unsupported database, you will have to tell OpenJPA what
org.apache.openjpa.jdbc.sql.DBDictionary
to use.
The DBDictionary
abstracts away the differences between
databases. You can plug a dictionary into OpenJPA using the
openjpa.jdbc.DBDictionary
configuration property. The built-in dictionaries are listed
below. If you are using an unsupported database, you may have to write your own
DBDictionary
subclass, a simple process.
access
: Dictionary for Microsoft Access. This is an alias
for the
org.apache.openjpa.jdbc.sql.AccessDictionary
class.
db2
: Dictionary for IBM's DB2 database. This is an alias for
the
org.apache.openjpa.jdbc.sql.DB2Dictionary
class.
derby
: Dictionary for the Apache Derby database. This is an
alias for the
org.apache.openjpa.jdbc.sql.DerbyDictionary
class.
empress
: Dictionary for Empress database This is an alias
for the
org.apache.openjpa.jdbc.sql.EmpressDictionary
class.
foxpro
: Dictionary for Microsoft Visual FoxPro. This is an
alias for the
org.apache.openjpa.jdbc.sql.FoxProDictionary
class.
h2
: Dictionary for the H2 Database Engine. This is an
alias for the
org.apache.openjpa.jdbc.sql.H2Dictionary
class.
hsql
: Dictionary for the Hypersonic SQL database. This is an
alias for the
org.apache.openjpa.jdbc.sql.HSQLDictionary
class.
informix
: Dictionary for the Informix database. This is an
alias for the
org.apache.openjpa.jdbc.sql.InformixDictionary
class.
ingres
: Dictionary for Ingres. This is an alias for the
org.apache.openjpa.jdbc.sql.IngresDictionary
class.
jdatastore
: Dictionary for Borland JDataStore. This is an
alias for the
org.apache.openjpa.jdbc.sql.JDataStoreDictionary
class.
mariadb
: Dictionary for the MariaDB database. This is an alias
for the
org.apache.openjpa.jdbc.sql.MariaDBDictionary
class.
mysql
: Dictionary for the MySQL database. This is an alias
for the
org.apache.openjpa.jdbc.sql.MySQLDictionary
class.
oracle
: Dictionary for Oracle. This is an alias for the
org.apache.openjpa.jdbc.sql.OracleDictionary
class.
pointbase
: Dictionary for Pointbase Embedded database. This
is an alias for the
org.apache.openjpa.jdbc.sql.PointbaseDictionary
class.
postgres
: Dictionary for PostgreSQL. This is an alias for
the
org.apache.openjpa.jdbc.sql.PostgresDictionary
class.
soliddb
: Dictionary for IBM's SolidDB database.
This is an alias for the
org.apache.openjpa.jdbc.sql.SolidDBDictionary
class.
sqlserver
: Dictionary for Microsoft's SQL Server database.
This is an alias for the
org.apache.openjpa.jdbc.sql.SQLServerDictionary
class.
sybase
: Dictionary for Sybase. This is an alias for the
org.apache.openjpa.jdbc.sql.SybaseDictionary
class.
The example below demonstrates how to set a dictionary and configure its
properties in your configuration file. The DBDictionary
property uses OpenJPA's plugin syntax
.
Example 4.7. Specifying a DBDictionary
<property name="openjpa.jdbc.DBDictionary" value="hsql(SimulateLocking=true)"/>
The standard dictionaries all recognize the following properties. These
properties will usually not need to be overridden, since the dictionary
implementation should use the appropriate default values for your database. You
typically won't use these properties unless you are designing your own
DBDictionary
for an unsupported database.
AllowsAliasInBulkClause
:
When true, SQL delete and update statements may use table aliases.
ArrayTypeName
: The overridden default column type for
java.sql.Types.ARRAY
. This is used only when the schema is
generated by the mappingtool
.
AutoAssignClause
: The column definition clause to append to
a creation statement. For example, "AUTO_INCREMENT"
for
MySQL. This property is set automatically in the dictionary, and should not need
to be overridden, and is only used when the schema is generated using the
mappingtool
.
AutoAssignTypeName
:
The column type name for auto-increment
columns. For example, "BIGSERIAL"
for PostgreSQL. This
property is set automatically in the dictionary and should not need to be
overridden. It is used only when the schema is generated using the
mappingtool
.
BatchLimit
:
The default batch limit for sending multiple SQL statements at once to the
database. A value of -1 indicates unlimited batching, and any positive integer
indicates the maximum number of SQL statements to batch together.
Defaults to 0 which disables batching.
BigintTypeName
: The overridden default column type for
java.sql.Types.BIGINT
. This is used only when the schema is
generated by the mappingtool
.
BinaryTypeName
: The overridden default column type for
java.sql.Types.BINARY
. This is used only when the schema is
generated by the mappingtool
.
BitTypeName
: The overridden default column type for
java.sql.Types.BIT
. This is used only when the schema is generated by
the mappingtool
.
BlobBufferSize
: This property establishes the buffer size in
the INSERT/UPDATE
operations with an
java.io.InputStream
. This is only used with OpenJPA's
Section 7.11, “
LOB Streaming
”. Defaults to 50000.
BlobTypeName
: The overridden default column type for
java.sql.Types.BLOB
. This is used only when the schema is
generated by the mappingtool
.
BooleanRepresentation
:
The overridden default representation for java.lang.Boolean
or
boolean
fields in JPA Entities. A
org.apache.openjpa.jdbc.sql.BooleanRepresentation
describes how Boolean values in entities get mapped into the database by default.
Note that you additionally might need to define the BooleanTypeName
BitTypeName
settings to fit your selected BooleanRepresenation.
BooleanTypeName
:
The overridden default column type for
java.sql.Types.BOOLEAN
. This is used only when the schema
is generated by the mappingtool
.
CastFunction
:
The SQL function call to cast a value to another SQL type.
Use the tokens {0}
and {1}
to represent
the two arguments. The result of the function is convert the
{0}
value to a {1}
type.
The default is "CAST({0} AS {1})"
.
CatalogSeparator
: The string the database uses to delimit
between the schema name and the table name. This is typically "."
, which is the default.
CharTypeName
: The overridden default column type for
java.sql.Types.CHAR
. This is used only when the schema is
generated by the mappingtool
.
CharacterColumnSize
: The default size of varchar
and char
columns. Typically 255.
ClobBufferSize
: This property establish the buffer size in
the INSERT/UPDATE
operations with a
java.io.Reader
. This is only used with OpenJPA's
Section 7.11, “
LOB Streaming
”. Defaults to 50000.
ClobTypeName
: The overridden default column type for
java.sql.Types.CLOB
. This is used only when the schema is
generated by the mappingtool
.
ClosePoolSQL
:
A special command to issue to the database when shutting down the pool.
Usually the pool of connections to the database is closed when the
application is ending. For embedded databases, whose lifecycle is
coterminous with the application, there may be a special
command, usually "SHUTDOWN"
,
that will cause the embedded database to close cleanly.
Defaults to null
.
ConcatenateFunction
:
The SQL function call or operation to concatenate two strings.
Use the tokens {0}
and {1}
to represent
the two arguments. The result of the function or operation is to concatenate
the {1}
string to the end of the {0}
string. Defaults to "({0}||{1})"
.
ConstraintNameMode
: When creating constraints, whether to
put the constraint name before the definition ("before"
),
just after the constraint type name ("mid"
), or after the
constraint definition ("after"
).
Defaults to "before"
.
CreatePrimaryKeys
: When false, do not
create database primary keys for identifiers. Defaults to true
.
CrossJoinClause
: The clause to use for a cross join
(cartesian product). Defaults to "CROSS JOIN"
.
CurrentDateFunction
:
The SQL function call to obtain the current date from the database.
Defaults to "CURRENT_DATE"
.
CurrentTimeFunction
:
The SQL function call to obtain the current time from the database.
Defaults to "CURRENT_TIME"
.
CurrentTimestampFunction
:
The SQL function call to obtain the current timestamp from the database.
Defaults to "CURRENT_TIMESTAMP"
.
DateFractionDigits
Some databases support to store sub-second fraction values.
The digits to store can sometimes be configured.
This value defines the default number of digits to store in the database.
A dateFractionDigits=3
will e.g. lead to a DATETIME(3)
on some databases.
Note that this default can be overwritten to an integer value n per column via
@Column(scale=n)
.
A @Column(scale=-1)
will set the fraction digits to zero.
DatePrecision
:
The database is able to store time values to this degree of precision,
which is expressed in nanoseconds.
This value is usually one million, meaning that the database is able
to store time values with a precision of one millisecond. Particular
databases may have more or less precision.
OpenJPA will round all time values to this degree of precision
before storing them in the database. This property can be set to one
of the following precisions:
DECI
: 100000000
CENIT
: 10000000
MILLI (default precision)
: 1000000
MICRO
: 1000
NANO (max precision)
: 1
DateMillisecondBehavior
:
When retrieving a Date
value from a database which stores the value in
a TIMESTAMP column, the values retrieved will be rounded to the nearest
millisecond. So a date of '2010-01-01 12:00:00.687701' stored in the
database will become '2010-01-01 12:00:00.688' in the Date
field of the
entity. The following date stored in the database as '9999-12-31 23:59:59.9999'
will become '10000-01-01 00:00:00.000'. This rounding may not be desirable. With this
property, a user has options which will direct OpenJPA how to handle the milliseconds. This
property can be set to one of the enums defined in
DBDictionary.DateMillisecondBehaviors
. The options defined in
DBDictionary.DateMillisecondBehaviors
are as follows:
DateMillisecondBehaviors.ROUND
: This is the default. The
Date
will be rounded to the nearest millisecond, as described above.
DateMillisecondBehaviors.DROP
: The milliseconds will be dropped, thus
rounding is not performed. As an example, a date of '2010-01-01 12:00:00.687701' stored in the
database will become '2010-01-01 12:00:00.000' in the Date
field of the
entity.
DateMillisecondBehaviors.RETAIN
: The milliseconds will not be rounded, but will
be retained. As an example, a date of '2010-01-01 12:00:00.687701' stored in the
database will become '2010-01-01 12:00:00.687' in the Date
field of the
entity.
DateTypeName
: The overridden default column type for
java.sql.Types.DATE
. This is used only when the schema is
generated by the mappingtool
.
DecimalTypeName
: The overridden default column type for
java.sql.Types.DECIMAL
. This is used only when the schema is
generated by the mappingtool
.
DelimitedCase
: The case to use when querying the database
about identifiers that have been delimited. It defaults to preserving the
case of the originally specified name. Available values are:
upper, lower, preserve.
DisableAlterSeqenceIncrementBy
: OpenJPA attempts to execute
an ALTER SEQUENCE....INCREMENT BY SQL statement for a user defined sequence. This
is done to ensure that the 'allocationSize' value defined by the entity's sequence,
or default value, matches the sequence defined in the database. For example, with
an allocationSize of 1000 for a sequence named 'SEQ_JPASAMPLE', the following SQL
will be generated (the SQL might vary slightly depending on the databases):
ALTER SEQUENCE SEQ_JPASAMPLE INCREMENT BY 1000
. If the user
executing this command doesn't have permissions to execute the command, it will
fail and in turn OpenJPA will disable sequence caching. If a user wants to disable
this SQL command, this property can be set to true. However, the user must ensure
that the entities defined sequence is kept in synch with the sequence defined in the
database. Defaults to false.
DisableSchemaFactoryColumnTypeErrors
: When something other than the default
SchemaFactory is used, up-front mapping validation is performed against the database schema. As
part of the validation, OpenJPA will verify a persistence class column's type against the column type
defined in the database schema. If a mismatch is found, OpenJPA will throw an exception to flag the
mismatch types and will not allow processing to continue. This can be limiting, especially if the
JDBC driver and/or database can properly handle the mismatch. Set this property to true to disable
column type mismatch errors. Defaults to false.
DistinctCountColumnSeparator
: The string the database uses
to delimit between column expressions in a SELECT COUNT(DISTINCT
column-list)
clause. Defaults to null
for most databases, meaning that
multiple columns in a distinct COUNT clause are not supported.
DistinctTypeName
: The overridden default column type for
java.sql.Types.DISTINCT
. This is used only when the schema
is generated by the mappingtool
.
DoubleTypeName
: The overridden default column type for
java.sql.Types.DOUBLE
. This is used only when the schema is
generated by the mappingtool
.
DriverVendor
: The vendor of the particular JDBC driver you
are using. Some dictionaries must alter their behavior depending on the driver
vendor. Dictionaries usually detect the driver vendor and set this property
themselves. See the VENDOR_XXX
constants defined in the
DBDictionary
Javadoc for available options.
DropTableSQL
:
The SQL statement used to drop a table. Use the token {0}
as the argument for the table name.
Defaults to "DROP TABLE {0}"
.
FixedSizeTypeNames
:
A comma separated list of additional database types that have a size
defined by the database. In other words, when a column of a fixed
size type is declared, its size cannot be defined by the user. Common
examples would be DATE
, FLOAT
,
and INTEGER
.
Each database dictionary has its own internal set of fixed size type names
that include the names mentioned here and many others.
Names added to this property are added to the dictionary's internal set.
Defaults to null
.
FloatTypeName
: The overridden default column type for
java.sql.Types.FLOAT
. This is used only when the schema is
generated by the mappingtool
.
ForUpdateClause
: The clause to append to SELECT
statements to issue queries that obtain pessimistic locks. Defaults
to "FOR UPDATE"
.
GetStringVal
:
A special function to return the value of an XML
column in a select statement. For example, Oracle uses
".getClobVal()"
, as in
"SELECT t0.xmlcol.getClobVal() FROM xmltab t0"
.
Defaults to the empty string.
InClauseLimit
:
The maximum number of elements in an IN
clause. OpenJPA
works around cases where the limit is exceeded. Defaults to -1 meaning
no limit.
IndexPhysicalForeignKeys
:
Whether a search Index should automatically get created on a physical foreign key.
Some databases, like MySQL, handle this internally, so we do not need to generate
an explicit Index in our DDL. Other databases need an explicit serach index
on foreign key columns to improve performance.
IndexPhysicalForeignKeys defaults to true for Oracle, MS-SQL and PostgreSQL.
InitializationSQL
: A piece of SQL to issue against the
database whenever a connection is retrieved from the DataSource
.
InnerJoinClause
: The clause to use for an inner join.
Defaults to "INNER JOIN"
.
IntegerTypeName
: The overridden default column type for
java.sql.Types.INTEGER
. This is used only when the schema is
generated by the mappingtool
.
JavaObjectTypeName
: The overridden default column type for
java.sql.Types.JAVAOBJECT
. This is used only when the schema
is generated by the mappingtool
.
JoinSyntax
: The SQL join syntax to use in select statements.
See Section 6, “
Setting the SQL Join Syntax
”.
LastGeneratedKeyQuery
: The query to issue to obtain the last
automatically generated key for an auto-increment column. For example,
"SELECT LAST_INSERT_ID()"
for MySQL. This property is set
automatically in the dictionary, and should not need to be overridden.
If SupportsGetGeneratedKeys
is true, the query will not
be issued but a more efficient JDBC 3.0 mechanism for obtaining generated
keys will be used instead.
LeadingDelimiter
: The characters to use as the leading delimiter
for a delimited identifier. The default value is a double quote,
(")
. See
Section 4.7, “
Delimited Identifiers Support
” for
the default value for some specific databases.
LongVarbinaryTypeName
: The overridden default column type
for java.sql.Types.LONGVARBINARY
. This is used only when the
schema is generated by the mappingtool
.
LongVarcharTypeName
: The overridden default column type for
java.sql.Types.LONGVARCHAR
. This is used only when the
schema is generated by the mappingtool
.
MaxAutoAssignNameLength
: Set this property to the maximum
length of the sequence name used for auto-increment columns. Names longer than
this value are truncated. Defaults to 31.
MaxColumnNameLength
: The maximum number of characters in a
column name. Defaults to 128.
MaxConstraintNameLength
: The maximum number of characters in
a constraint name. Defaults to 128.
MaxEmbeddedBlobSize
:
When greater than -1, the maximum size of a BLOB
value
that can be sent directly to the database within an insert or update statement.
Values whose size is greater than MaxEmbeddedBlobSize
force
OpenJPA to work around this limitation. A value of -1 means that there is
no limitation. Defaults to -1.
MaxEmbeddedClobSize
:
When greater than -1, the maximum size of a CLOB
value
that can be sent directly to the database within an insert or update statement.
Values whose size is greater than MaxEmbeddedClobSize
force
OpenJPA to work around this limitation. A value of -1 means that there is
no limitation. Defaults to -1.
MaxIndexNameLength
: The maximum number of characters in an
index name. Defaults to 128.
MaxIndexesPerTable
: The maximum number of indexes that can
be placed on a single table. Defaults to no limit.
MaxTableNameLength
: The maximum number of characters in a
table name. Defaults to 128.
NameConcatenator
: The value used when names are concatenated to
create a generated name. The default value is the underscore "_"
.
NextSequenceQuery
: A SQL string for obtaining a native
sequence value. May use a placeholder of {0}
for the variable
sequence name and {1}
for sequence increment.
Defaults to a database-appropriate value. For example,
"SELECT {0}.NEXTVAL FROM DUAL"
for Oracle database.
NullTypeName
: The overridden default column type for
java.sql.Types.NULL
. This is used only when the schema is
generated by the mappingtool
.
NumericTypeName
: The overridden default column type for
java.sql.Types.NUMERIC
. This is used only when the schema is
generated by the mappingtool
.
OtherTypeName
: The overridden default column type for
java.sql.Types.OTHER
. This is used only when the schema is
generated by the mappingtool
.
OuterJoinClause
: The clause to use for an left outer join.
Defaults to "LEFT OUTER JOIN"
.
Platform
:
The name of the database that this dictionary targets.
Defaults to "Generic"
, but all dictionaries override this
value.
RangePosition
:
Indicates where to specify in the SQL select statement the range, if any,
of the result rows to be returned.
When limiting the number of returned result rows to a subset of all those
that satisfy the query's conditions, the position of the range clause
varies by database.
Defaults to 0, meaning that the range
is expressed at the end of the select statement but before any locking clause.
See the RANGE_XXX constants defined in DBDictionary
.
RealTypeName
: The overridden default column type for
java.sql.Types.REAL
. This is used only when the schema is
generated by the mappingtool
.
RefTypeName
: The overridden default column type for
java.sql.Types.REF
. This is used only when the schema is generated by
the mappingtool
.
RequiresAliasForSubselect
: When true, the database
requires that subselects in a FROM clause be assigned an alias.
RequiresAutoCommitForMetadata
: When true, the JDBC driver
requires that autocommit be enabled before any schema interrogation operations
can take place.
RequiresCastForComparisons
:
When true, comparisons of two values of different types or
of two literals requires a cast in the generated SQL.
Defaults to false
.
RequiresCastForMathFunctions
:
When true, math operations on two values of different types or
on two literals requires a cast in the generated SQL.
Defaults to false
.
RequiresConditionForCrossJoin
: Some databases require that
there always be a conditional statement for a cross join. If set, this parameter
ensures that there will always be some condition to the join clause.
RequiresTargetForDelete
:
When true, the database requires a target for delete statements. Defaults
to false
.
ReservedWords
: A comma-separated list of reserved words for
this database, beyond the standard SQL92 keywords.
SchemaCase
: The case to use when querying the database
metadata about schema components. Defaults to making all names upper case.
Available values are: upper, lower, preserve
.
SearchStringEscape
:
The default escape character used when generating SQL LIKE
clauses. The escape character is used to escape the wildcard meaning of the
_
and %
characters.
Note: since JPQL provides the ability to define the escape character in
the query, this setting is primarily used when translating other query
languages, such as JDOQL. Defaults to "\\"
(a single backslash in Java speak).
RequiresSearchStringEscapeForLike
:
When true, the database requires an escape string for queries that use
LIKE
. The escape string can be specified using
searchStringEscape
. Defaults to false
.
SelectWords
: A comma-separated list of keywords which may be
used to start a SELECT statement for this database. If an application executes
a native SQL statement which begins with SelectWords OpenJPA will treat the
statement as a SELECT statement rather than an UPDATE statement.
SequenceNameSQL
:
Additional phrasing to use with SequenceSQL
.
Defaults to null
.
SequenceSQL
:
General structure of the SQL query to use when interrogating the database
for sequence names.
As there is no standard way to obtain sequence names,
it defaults to null
.
SequenceSchemaSQL
:
Additional phrasing to use with SequenceSQL
.
Defaults to null
.
SimulateLocking
: Some databases do not support pessimistic
locking, which will result in an exception when you attempt a
transaction while using the pessimistic lock manager.
Setting this property to true
suppresses the
locking of rows in the database, thereby allowing pessimistic transactions
even on databases that do not support locking. At the same time, setting this
property to true
means that you do not obtain the semantics
of a pessimistic
transaction with the database. Defaults to false
.
SmallintTypeName
: The overridden default column type for
java.sql.Types.SMALLINT
. This is used only when the schema
is generated by the mappingtool
.
StorageLimitationsFatal
: When true, any data
truncation/rounding that is performed by the dictionary in order to store a
value in the database will be treated as a fatal error, rather than just issuing
a warning.
StoreCharsAsNumbers
: Set this property to false
to store Java char
fields as CHAR
values rather than numbers. Defaults to true
.
StoreLargeNumbersAsStrings
: When true, the dictionary
prefers to store Java fields of
type BigInteger
and BigDecimal
as string values in the database. Likewise, the dictionary will instruct
the mapping tool to map these Java types to character columns.
Because some databases have limitations on the number of digits that can
be stored in a numeric column (for example, Oracle can only store 38
digits), this option may be necessary for some applications.
Note that this option may prevent OpenJPA from executing meaningful numeric
queries against the columns. Defaults to false
.
StringLengthFunction
: Name of the SQL function for getting
the length of a string. Use the token {0}
to represent the
argument.
StructTypeName
: The overridden default column type for
java.sql.Types.STRUCT
. This is used only when the schema is
generated by the mappingtool
.
SubstringFunctionName
: Name of the SQL function for getting
the substring of a string.
SupportsAlterTableWithAddColumn
: When true, the database
supports adding a new column in an ALTER TABLE statement.
Defaults to true
.
SupportsAlterTableWithDropColumn
: When true, the database
supports dropping a column in an ALTER TABLE statement.
Defaults to true
.
SupportsAutoAssign
:
When true, the database supports auto-assign columns, where the value of
column is assigned upon insertion of the row into the database.
Defaults to false
.
SupportsCascadeDeleteAction
: When true, the database supports
the CASCADE
delete action on foreign keys.
Defaults to true
.
SupportsCascadeUpdateAction
:
When true, the database supports the CASCADE
update action on foreign keys. Defaults to true
.
SupportsComments
:
When true, comments can be associated with the table in the table creation
statement. Defaults to false
.
SupportsDefaultDeleteAction
: When true, the database supports
the SET DEFAULT
delete action on foreign keys.
Defaults to true
.
SupportsDefaultUpdateAction
:
When true, the database supports the SET DEFAULT
update
action on foreign keys. Defaults to true
.
SupportsDeferredConstraints
: When true, the database
supports deferred constraints. The
database supports deferred constraints by checking for constraint
violations when the transaction commits, rather than checking for
violations immediately after receiving each SQL statement within the
transaction. Defaults to true
.
SupportsDelimitedIdentifiers
: When true, the database
supports delimited identifiers. It defaults to true
.
SupportsForeignKeys
: When true, the database supports foreign
keys. Defaults to true
.
SupportsForeignKeysComposite
: When true, the database supports
composite foreign keys. Defaults to true
.
SupportsGetGeneratedKeys
: When true, OpenJPA will use
java.sql.Statement.getGeneratedKeys
method to obtain
values of auto-increment columns. When false, a query specified by
LastGeneratedKeyQuery
will be used for that purpose.
If not set, the value will be auto-detected by querying the JDBC driver.
Setting the value to true requires that the JDBC
driver supports version 3.0 or higher of the JDBC specification
and supports the java.sql.Statement.getGeneratedKeys
method.
SupportsHaving
: When true, the database supports HAVING
clauses in selects.
SupportsLockingWithDistinctClause
: When true, the
database supports FOR UPDATE
select clauses with
DISTINCT
clauses.
SupportsLockingWithInnerJoin
: When true, the database
supports FOR UPDATE
select clauses with inner join queries.
SupportsLockingWithMultipleTables
: When true, the
database supports FOR UPDATE
select clauses that select from
multiple tables.
SupportsLockingWithOrderClause
: When true, the database
supports FOR UPDATE
select clauses with ORDER BY
clauses.
SupportsLockingWithOuterJoin
: When true, the database
supports FOR UPDATE
select clauses with outer join queries.
SupportsLockingWithSelectRange
: When true, the database
supports FOR UPDATE
select clauses with queries that select a
range of data using LIMIT
, TOP
or the
database equivalent. Defaults to true
.
SupportsModOperator
:
When true, the database supports the modulus operator (%
)
instead of the MOD
function.
Defaults to false
.
SupportsMultipleNontransactionalResultSets
: When true, a
nontransactional connection is capable of having multiple open
ResultSet
instances.
SupportsNullDeleteAction
: When true, the database supports
the SET NULL
delete action on foreign keys.
Defaults to true
.
SupportsNullTableForGetColumns
: When true, the database
supports passing a null
parameter to
DatabaseMetaData.getColumns
as an optimization to get information
about all the tables. Defaults to true
.
SupportsNullTableForGetImportedKeys
: When true, the
database supports passing a null
parameter to
DatabaseMetaData.getImportedKeys
as an optimization to get
information about all the tables. Defaults to false
.
SupportsNullTableForGetIndexInfo
: When true, the database
supports passing a null
parameter to
DatabaseMetaData.getIndexInfo
as an optimization to get information
about all the tables. Defaults to false
.
SupportsNullTableForGetPrimaryKeys
: When true, the
database supports passing a null
parameter to
DatabaseMetaData.getPrimaryKeys
as an optimization to get
information about all the tables. Defaults to false
.
SupportsNullUpdateAction
:
When true, the database supports the SET NULL
update
action on foreign keys. Defaults to true
.
SupportsQueryTimeout
: When true, the JDBC driver supports
calls to java.sql.Statement.setQueryTimeout
.
AllowQueryTimeoutOnFindUpdate
: The JPA Specification defines the
jakarta.persistence.query.timeout, in milliseconds, as a hint to the provider. The hint
is used for Query operations. This property, when set to true, will allow the query timeout hint
to apply to EntityManager operations. For example, when a 'find' is executed and the resultant
entity updated, the query timeout will apply to the SQL update operation. This property defaults
to false.
SupportsRestrictDeleteAction
: When true, the database
supports the RESTRICT
delete action on foreign keys.
Defaults to true
.
SupportsRestrictUpdateAction
:
When true, the database supports the RESTRICT
update
action on foreign keys. Defaults to true
.
SupportsSchemaForGetColumns
: When false, the database
driver does not support using the schema name for schema reflection on column
names.
SupportsSchemaForGetTables
: If false, then the database
driver does not support using the schema name for schema reflection on table
names.
SupportsSelectEndIndex
: When true, the database can create a
select that is limited to the first N results.
SupportsSelectForUpdate
: When true, the database supports
SELECT
statements with a pessimistic locking
(FOR UPDATE
) clause. Defaults to true
.
SupportsSelectStartIndex
: When true, the database can create a
select that skips the first N results.
SupportsSimpleCaseExpression
: When true, the database supports
the simple form of CASE
expression:
CASE <a> WHEN <b> THEN <c> WHEN <d> THEN <e> ELSE <f> END
.
When false, the general form of CASE
expression will be used:
CASE WHEN <a> = <b> THEN <c> WHEN <a> = <d> THEN <e> ELSE <f> END
.
Defaults to true
.
SupportsSubselect
: When true, the database supports subselects
in queries.
SupportsTimestampNanos
: When true, the database supports
nanoseconds with TIMESTAMP columns.
Defaults to true
.
SupportsUniqueConstraints
: When true, the database supports
unique constraints. Defaults to true
.
SupportsXMLColumn
:
When true, the database supports an XML column type. See
Section 7.10, “
XML Column Mapping
”
for information on using this capability. Defaults to false
.
SystemSchemas
: A comma-separated list of schema names that
should be ignored.
SystemTables
: A comma-separated list of table names that
should be ignored.
TableForUpdateClause
: The clause to append to the end of
each table alias in queries that obtain pessimistic locks.
Defaults to null
.
tableLengthIncludesSchema
: Whether the max length for a table name includes the table's schema.
Defaults to false
.
TableTypes
: Comma-separated list of table types to use when
looking for tables during schema reflection, as defined in the
java.sql.DatabaseMetaData.getTableInfo
JDBC method. An example is:
"TABLE,VIEW,ALIAS"
. Defaults to "TABLE"
.
TimeTypeName
: The overridden default column type for
java.sql.Types.TIME
. This is used only when the schema is
generated by the mappingtool
.
TimestampTypeName
: The overridden default column type for
java.sql.Types.TIMESTAMP
. This is used only when the schema
is generated by the mappingtool
.
TinyintTypeName
: The overridden default column type for
java.sql.Types.TINYINT
. This is used only when the schema is
generated by the mappingtool
.
ToLowerCaseFunction
: Name of the SQL function for converting
a string to lower case. Use the token {0}
to represent the
argument.
ToUpperCaseFunction
: SQL function call for converting a
string to upper case. Use the token {0}
to represent the
argument.
TrailingDelimiter
: The characters to use as the trailing delimiter
for a delimited identifier. The default value is a double quote,
(")
. See
Section 4.7, “
Delimited Identifiers Support
” for
the default value for some specific databases.
TrimBothFunction
:
The SQL function call to trim any number of a particular character
from both the start and end of a string.
Note: some databases do not support specifying the character in which
case only spaces or whitespace can be trimmed.
Use the token {1}
when possible to represent the character,
and the token {0}
to represent the string.
Defaults to "TRIM(BOTH {1} FROM {0})"
.
TrimLeadingFunction
:
The SQL function call to trim any number of a particular character
from the start of a string.
Note: some databases do not support specifying the character in which
case only spaces or whitespace can be trimmed.
Use the token {1}
when possible to represent the character,
and the token {0}
to represent the string.
Defaults to "TRIM(LEADING {1} FROM {0})"
.
TrimStringColumns
: When true
, the resulting String from
ResultSet.getString
will be trimmed of trailing white space. Defaults
to false
.
TrimTrailingFunction
:
The SQL function call to trim any number of a particular character
from the end of a string.
Note: some databases do not support specifying the character in which
case only spaces or whitespace can be trimmed.
Use the token {1}
when possible to represent the character,
and the token {0}
to represent the string.
Defaults to "TRIM(TRAILING {1} FROM {0})"
.
UseGetBestRowIdentifierForPrimaryKeys
: When true,
metadata queries will use DatabaseMetaData.getBestRowIdentifier
to obtain information about primary keys, rather than
DatabaseMetaData.getPrimaryKeys
.
UseGetBytesForBlobs
: When true,
ResultSet.getBytes
will be used to obtain blob data rather than
ResultSet.getBinaryStream
.
UseGetObjectForBlobs
: When true,
ResultSet.getObject
will be used to obtain blob data rather than
ResultSet.getBinaryStream
.
UseGetStringForClobs
: When true,
ResultSet.getString
will be used to obtain clob data rather than
ResultSet.getCharacterStream
.
UseJDBC4SetBinaryStream
: When true, an attempt will be made to obtain
a JDBC 4.0 version of PreparedStatement.setBinaryStream
.
When false, a setBinaryStream
is used which takes the length of the
stream. OpenJPA uses a -1 for the length since OpenJPA doesn't know the length of the stream.
A few JDBC drivers check the length and throw an exception when the length is less than zero.
When this property is set to true, and an applicable JDK and JDBC 4.0 driver is available, a
version of setBinaryStream
will be used which does not take a length.
The default value of this property is true.
UseNativeSequenceCache
: This property was introduced in
the 2.1.2 release to indicate (when set to false
) that OpenJPA
should not use the CACHE
clause when creating a native sequence; instead
the INCREMENT BY
clause gets its value equal to the allocationSize
property. In the 2.2.0 release, code was added to allow said functionality by
default (see OPENJPA-1376).
For forward compatibility, this property still remains, however it has
been deprecated and will eventually be removed. Setting this property
has no effect and any occurrence of it should be removed.
UseSchemaName
: If false
, then avoid
including the schema name in table name references. Defaults to true
.
UseSetBytesForBlobs
: When true,
PreparedStatement.setBytes
will be used to set blob data, rather
than PreparedStatement.setBinaryStream
.
UseSetStringForClobs
: When true,
PreparedStatement.setString
will be used to set clob data, rather
than PreparedStatement.setCharacterStream
.
UseWildCardForCount
: When true, the JPQL COUNT
aggregate function will be translated into SQL COUNT(*)
expression
if the SQL query does not involve joins. Defaults to false
.
ValidationSQL
: The SQL used to validate that a connection is
still in a valid state. For example, "SELECT SYSDATE FROM DUAL"
for Oracle.
VarbinaryTypeName
: The overridden default column type for
java.sql.Types.VARBINARY
. This is used only when the schema
is generated by the mappingtool
.
VarcharTypeName
: The overridden default column type for
java.sql.Types.VARCHAR
. This is used only when the schema is
generated by the mappingtool
.
XmlTypeName
:
The column type name for XML columns. This
property is set automatically in the dictionary and should not need to be
overridden. It is used only when the schema is generated using the
mappingtool
. Defaults to "XML"
.
The firebird
dictionary understands the following additional
properties:
FirebirdVersion
: The database version OpenJPA connects to.
This property affects the SQL statements executed by OpenJPA.
Available values are: 15, 20 and 21
- they indicate Firebird versions 1.5, 2.0 and 2.1 respectively.
If not set, the value will be auto-detected.
IndexedVarcharMaxSizeFB15
: Firebird 1.5 imposes
tight limits on index size. In particular, an indexed
VARCHAR
column size cannot exceed 252.
When schema is created,
OpenJPA will use this property to reduce the size
of indexed VARCHAR
columns.
Defaults to 252 but you might want to decrease this value if multi-column
indexes are used. If the Firebird version is 2.0 or later or
schema creation is not used, this property does not matter.
RangeSyntax
: Firebird 2.0 and later support two
ways of handling queries that select a range of data:
"FIRST <p> SKIP <q>"
and
"ROWS <m> TO <n>"
. Earlier versions support only
"FIRST <p> SKIP <q>"
syntax.
This property determines the syntax to be used.
Available values are:
"firstskip"
and "rows"
.
Defaults to using "ROWS <m> TO <n>"
if the
Firebird version is 2.0 or later, and
"FIRST <p> SKIP <q>"
otherwise.
The mysql
dictionary also understands the following
properties:
DateFractionDigits
:
Since MySQL 5.8 a timestamp (DATETIME
) can store up to 6 sub-second fractions.
The default in MySQL and OpenJPA is 0 for backward compatibility reasons.
This default can be changed by setting DateFractionDigits
to the number of
sub-second fraction digits to be stored. This will e.g. result in a DATETIME(6)
column.
The number of fraction digits to be generated can also be tweaked via the
@Column(scale=n)
annotation, where n is the number of digits.
This setting has primarily an impact on the generated SQL.
DriverDeserializesBlobs
: Many older MySQL drivers
automatically deserialize BLOBs on calls to
ResultSet.getObject
. The
MySQLDictionary
overrides the standard
DBDictionary.getBlobObject
method to take this into account.
Defaults to true
if driver version is less than 5.0,
false
otherwise. If your driver deserializes
automatically, you may want to set this property to true
.
TableType
: The MySQL table type to use when creating tables.
Defaults to "innodb"
.
UseClobs
: Some older versions of MySQL do not handle CLOBs
correctly. To disable CLOB functionality, set this to false
.
Defaults to true
.
OptimizeMultiTableDeletes
: MySQL as of version 4.0.0
supports multiple tables in DELETE
statements. When
this option is set, OpenJPA will use that syntax when doing bulk deletes
from multiple tables. This can happen when the
deleteTableContents
SchemaTool
action is used. (See Section 13, “
Schema Tool
” for
more info about deleteTableContents
.) Defaults to
false
, since the statement may fail if using InnoDB
tables and delete constraints.
Starting with Connector/J 3.1.7, MySQL supports a variant of the driver
com.mysql.jdbc.ReplicationDriver
that automatically sends
queries to a read/write master, or a failover or round-robin load balanced set
of slaves based on the state of read-only status of the connection.
See
MySQL Reference for more details.
This replication feature can be used transparently with OpenJPA application by following configuration:
openjpa.ConnectionDriverName: com.mysql.jdbc.ReplicationDriver
openjpa.ConnectionFactoryProperties: autoReconnect=true,roundRobinLoadBalance=true
OpenJPA will use a read-only connection with replicated database configuration and will automatically switch the connection to a non-readonly mode if the transaction is writing to the database.
The oracle
dictionary understands the following additional
properties:
UseTriggersForAutoAssign
: When true, OpenJPA will allow
simulation of auto-increment columns by the use of Oracle triggers. OpenJPA will
assume that the current sequence value from the sequence specified in the
AutoAssignSequenceName
parameter will hold the value of the
new primary key for rows that have been inserted. For more details on
auto-increment support, see Section 4.4, “
Autoassign / Identity Strategy Caveats
”
.
AutoAssignSequenceName
: The global name of the sequence that
OpenJPA will assume to hold the value of primary key value for rows that use
auto-increment. If left unset, OpenJPA will use a sequence named
"<table name>_<column name>_SEQ"
.
MaxEmbeddedBlobSize
: Oracle is unable to persist BLOBs using
the embedded update method when BLOBs get over a certain size. The size depends
on database configuration, e.g. encoding. This property defines the maximum size
BLOB to persist with the embedded method. Defaults to 4000 bytes.
MaxEmbeddedClobSize
: Oracle is unable to persist CLOBs using
the embedded update method when CLOBs get over a certain size. The size depends
on database configuration, e.g. encoding. This property defines the maximum size
CLOB to persist with the embedded method. Defaults to 4000 characters.
SupportsSetClob
: This property was used in releases previous
to OpenJPA 2.2.0
to indicate that OpenJPA should attempt to use a Reader-based JDBC 4.0 method to
set CLOB or XML data. It allowed XMLType and CLOB values larger than 4000 bytes
to be used. For OpenJPA 2.2.0 and later releases, code was added to allow said
functionality by default (see OPENJPA-1691). For forward compatibility, this
property still remains, however it has been deprecated and will eventually be
removed. Setting this property has no effect and any occurrence of it should
be removed.
UseSetFormOfUseForUnicode
: Prior to Oracle 10i, statements
executed against unicode capable columns (the NCHAR
,
NVARCHAR
, NCLOB
Oracle types) required
special handling to be able to store unicode values. Setting this property to
true
(the default) will cause OpenJPA to attempt to detect when the column is
one of these types, and if so, will attempt to correctly configure the statement
using the OraclePreparedStatement.setFormOfUse
. For
more details, see the Oracle
JDBC Programming with Unicode. Note that this can only work if OpenJPA is able to
access the underlying OraclePreparedStatement
instance,
which may not be possible when using some third-party datasources. If OpenJPA
detects that this is the case, a warning will be logged.
The sybase
dictionary understands the following additional
properties:
The db2
dictionary understands the following additional
properties:
AppendExtendedExceptionText
: If false, OpenJPA will not call back to the database to
get extended exception text.
SupportsRowNum
: If true, OpenJPA will use ROWNUM
facility
for range based queries that set an offset and/or limit via setFirstResult()
and setMaxResult()
query methods. This property must be set to true
alongwith <lietral>SupportsSelectStartIndex</lietral> and <lietral>SupportsSelectEndIndex</lietral>.
By default, SupportsRowNum
is set to false
.
It is appropriate to set SupportsRowNum
to true
only when
DB2 version being used is 9.7 or later.
OpenJPA provides support for delimited identifiers as defined in the JPA 2.0 specification.
Identifiers can either be automatically delimited or individually manually
delimited. To have OpenJPA automatically delimit identifiers, add the
<delimited-identifiers/>
tag
to the mapping file as documented in the JPA specification.
You can manually delimit individual identifiers either in the annotations or in the
definitions in the mapping file. To delimit an identifier element in an annotation,
surround it with double quotes. In a mapping file, add
"e;
to both the beginning and end of the element.
When delimited identifiers has been specified, OpenJPA will delimit SQL identifiers
in the generated SQL statements. It will use database-specific delimiters as defined
in the appropriate database dictionary. By default, the leading and trailing
delimiters are both double quotes, (")
. Different defaults for other
dictionaries provided by OpenJPA are in the following table.
Table 4.1. Default delimiters for delimited identifiers
Dictionary | Leading Delimiter | Trailing Delimiter |
---|---|---|
MySQLDictionary | ` | ` |
AccessDictionary | [ | ] |
HerdDBDictionary | ` | ` |
Some databases support more than one set of delimiters, often based on configuration.
If you need values different than the default values, you can set the
LeadingDelimiter
and the
TrailingDelimiter
dictionary properties.
You can specify whether or not the particular database that you are using supports delimited
identifiers by setting the
SupportsDelimitedIdentifiers
dictionary property. If this value is set to false
, identifiers will not be automatically
delimited, even if the <delimited-identifiers/>
tag is specified
in the mapping file.
Limitation:
The columnDefinition
elements in identifiers
are not automatically delimited by OpenJPA when using the
<delimited-identifiers/>
tag
in the mapping file. If you want these to be delimited, you must manually delimit them in
the annotation or mapping file definitions.