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;
 

DB2

For DB2 the generated SELECT will look something like this

 WITH t(n) AS (
   SELECT 1 as n
     FROM (VALUES 1)
       UNION ALL
     SELECT n + 1 as n
       FROM t
      WHERE n < ?)
 SELECT next value for SEQ_CHILD_ID as 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

• DB2
• 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, GENERATOR_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

Methods inherited from interface org.hibernate.id.IdentifierGenerator

supportsJdbcBatchInserts

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