com.github.marschall.hibernate.batchsequencegenerator

Class BatchSequenceGenerator

java.lang.Object

com.github.marschall.hibernate.batchsequencegenerator.BatchSequenceGenerator

All Implemented Interfaces:

ExportableProducer, BulkInsertionCapableIdentifierGenerator, Configurable, IdentifierGenerator, PersistentIdentifierGenerator

public class BatchSequenceGenerator
extends Object
implements BulkInsertionCapableIdentifierGenerator, PersistentIdentifierGenerator, Configurable

A sequence generator that uses a recursive query to fetch multiple values from a sequence in a single database access.

Parameters

The following configuration parameters are supported:

"sequence"

mandatory, name of the sequence to use

"fetch_size"

optional, how many sequence numbers should be fetched at a time, default is 10

SQL

Per default the generated SELECT will look something like this

 WITH RECURSIVE t(n, level_num) AS (
   SELECT nextval(seq_xxx) as n, 1 as level_num
     UNION ALL
   SELECT nextval(seq_xxx) as n, level_num + 1 as level_num
   FROM t
   WHERE level_num < ?)
 SELECT n FROM t;
 

HSQLDB

For HSQLDB the generated SELECT will look something like this

 SELECT next value for seq_parent_id
 FROM UNNEST(SEQUENCE_ARRAY(1, ?, 1));
 

Oracle

For Oracle the generated SELECT will look something like this because Oracle does not support using recursive common table expressions to fetch multiple values from a sequence.

 SELECT seq_xxx.nextval
 FROM dual
 CONNECT BY rownum <= ?
 

SQL Server

For SQL Server the generated SELECT will look something like this

 WITH t(n) AS (
   SELECT 1 as n
     UNION ALL
   SELECT n + 1 as n FROM t WHERE n < ?)
 SELECT NEXT VALUE FOR seq_xxx as n FROM t
 

Firebird

For Firebird the generated SELECT will look something like this

 WITH RECURSIVE t(n, level_num) AS (
   SELECT NEXT VALUE FOR seq_xxx as n, 1 as level_num
   FROM rdb$database
     UNION ALL
   SELECT NEXT VALUE FOR seq_xxx as n, level_num + 1 as level_num
   FROM t
    WHERE level_num < ?)
 SELECT n FROM t
 

Database Support

The following RDBMS have been verified to work

• Firebird
• Oracle
• H2
• HSQLDB
• Postgres
• SQL Sever

In theory any RDBMS that supports WITH RECURSIVE and sequences is supported.

Field Summary

Fields

Modifier and Type	Field and Description
static int	DEFAULT_FETCH_SIZE The default value for FETCH_SIZE_PARAM.
static String	FETCH_SIZE_PARAM Indicates how many sequence values to fetch at once.
static String	SEQUENCE_PARAM Indicates the name of the sequence to use, mandatory.

Fields inherited from interface org.hibernate.id.PersistentIdentifierGenerator

CATALOG, IDENTIFIER_NORMALIZER, PK, SCHEMA, TABLE, TABLES

Fields inherited from interface org.hibernate.id.IdentifierGenerator

ENTITY_NAME, JPA_ENTITY_NAME

Constructor Summary

Constructors

Constructor and Description
BatchSequenceGenerator()

Method Summary

Modifier and Type	Method and Description
void	configure(Type type, Properties params, ServiceRegistry serviceRegistry)
String	determineBulkInsertionIdentifierGenerationSelectFragment(Dialect dialect)
Serializable	generate(SharedSessionContractImplementor session, Object object)
Object	generatorKey()
void	registerExportables(Database database)
String[]	sqlCreateStrings(Dialect dialect) Deprecated.
String[]	sqlDropStrings(Dialect dialect) Deprecated.
boolean	supportsBulkInsertionIdentifierGeneration()
String	toString()

Methods inherited from class java.lang.Object

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

Field Detail

SEQUENCE_PARAM

public static final String SEQUENCE_PARAM

Indicates the name of the sequence to use, mandatory.

See Also:

Constant Field Values

FETCH_SIZE_PARAM

public static final String FETCH_SIZE_PARAM

Indicates how many sequence values to fetch at once. The default value is DEFAULT_FETCH_SIZE.

See Also:

Constant Field Values

DEFAULT_FETCH_SIZE

public static final int DEFAULT_FETCH_SIZE

The default value for FETCH_SIZE_PARAM.

See Also:

Constant Field Values

Constructor Detail

BatchSequenceGenerator

public BatchSequenceGenerator()

Method Detail

configure

public void configure(Type type,
                      Properties params,
                      ServiceRegistry serviceRegistry)
               throws MappingException

Specified by:

configure in interface Configurable

Throws:

MappingException

supportsBulkInsertionIdentifierGeneration

public boolean supportsBulkInsertionIdentifierGeneration()

Specified by:

supportsBulkInsertionIdentifierGeneration in interface BulkInsertionCapableIdentifierGenerator

determineBulkInsertionIdentifierGenerationSelectFragment

public String determineBulkInsertionIdentifierGenerationSelectFragment(Dialect dialect)

Specified by:

determineBulkInsertionIdentifierGenerationSelectFragment in interface BulkInsertionCapableIdentifierGenerator

generate

public Serializable generate(SharedSessionContractImplementor session,
                             Object object)
                      throws HibernateException

Specified by:

generate in interface IdentifierGenerator

Throws:

HibernateException

generatorKey

public Object generatorKey()

Specified by:

generatorKey in interface PersistentIdentifierGenerator

sqlCreateStrings

@Deprecated
public String[] sqlCreateStrings(Dialect dialect)

Deprecated.

Specified by:

sqlCreateStrings in interface PersistentIdentifierGenerator

sqlDropStrings

@Deprecated
public String[] sqlDropStrings(Dialect dialect)

Deprecated.

Specified by:

sqlDropStrings in interface PersistentIdentifierGenerator

registerExportables

public void registerExportables(Database database)

Specified by:

registerExportables in interface ExportableProducer

toString

public String toString()

Overrides:

toString in class Object