io.hypersistence.utils.hibernate.id

Class BatchSequenceGenerator

java.lang.Object

io.hypersistence.utils.hibernate.id.BatchSequenceGenerator

All Implemented Interfaces:

org.hibernate.boot.model.relational.ExportableProducer, org.hibernate.id.BulkInsertionCapableIdentifierGenerator, org.hibernate.id.Configurable, org.hibernate.id.IdentifierGenerator, org.hibernate.id.PersistentIdentifierGenerator

public class BatchSequenceGenerator
extends Object
implements org.hibernate.id.BulkInsertionCapableIdentifierGenerator, org.hibernate.id.PersistentIdentifierGenerator, org.hibernate.id.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) AS (
   SELECT 1
     UNION ALL
   SELECT n + 1
   FROM t
   WHERE n < ?)
 SELECT nextval(seq_xxx)
   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
• MariaDB
• Postgres
• SQL Sever

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

For more details about how to use it, check out this article on vladmihalcea.com.

Since:

2.14.0

Author:

Philippe Marschall

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(org.hibernate.type.Type type, Properties params, org.hibernate.service.ServiceRegistry serviceRegistry)
String	determineBulkInsertionIdentifierGenerationSelectFragment(org.hibernate.dialect.Dialect dialect)
Serializable	generate(org.hibernate.engine.spi.SharedSessionContractImplementor session, Object object)
Object	generatorKey()
void	initialize(org.hibernate.boot.model.relational.SqlStringGenerationContext context)
void	registerExportables(org.hibernate.boot.model.relational.Database database)
String[]	sqlCreateStrings(org.hibernate.dialect.Dialect dialect)
String[]	sqlDropStrings(org.hibernate.dialect.Dialect dialect)
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.BulkInsertionCapableIdentifierGenerator

determineBulkInsertionIdentifierGenerationSelectFragment

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(org.hibernate.type.Type type,
                      Properties params,
                      org.hibernate.service.ServiceRegistry serviceRegistry)
               throws org.hibernate.MappingException

Specified by:

configure in interface org.hibernate.id.Configurable

Specified by:

configure in interface org.hibernate.id.IdentifierGenerator

Throws:

org.hibernate.MappingException

initialize

public void initialize(org.hibernate.boot.model.relational.SqlStringGenerationContext context)

Specified by:

initialize in interface org.hibernate.id.IdentifierGenerator

supportsBulkInsertionIdentifierGeneration

public boolean supportsBulkInsertionIdentifierGeneration()

Specified by:

supportsBulkInsertionIdentifierGeneration in interface org.hibernate.id.BulkInsertionCapableIdentifierGenerator

determineBulkInsertionIdentifierGenerationSelectFragment

public String determineBulkInsertionIdentifierGenerationSelectFragment(org.hibernate.dialect.Dialect dialect)

Specified by:

determineBulkInsertionIdentifierGenerationSelectFragment in interface org.hibernate.id.BulkInsertionCapableIdentifierGenerator

generate

public Serializable generate(org.hibernate.engine.spi.SharedSessionContractImplementor session,
                             Object object)
                      throws org.hibernate.HibernateException

Specified by:

generate in interface org.hibernate.id.IdentifierGenerator

Throws:

org.hibernate.HibernateException

generatorKey

public Object generatorKey()

Specified by:

generatorKey in interface org.hibernate.id.PersistentIdentifierGenerator

sqlCreateStrings

public String[] sqlCreateStrings(org.hibernate.dialect.Dialect dialect)

sqlDropStrings

public String[] sqlDropStrings(org.hibernate.dialect.Dialect dialect)

registerExportables

public void registerExportables(org.hibernate.boot.model.relational.Database database)

Specified by:

registerExportables in interface org.hibernate.boot.model.relational.ExportableProducer

Specified by:

registerExportables in interface org.hibernate.id.IdentifierGenerator

toString

public String toString()

Overrides:

toString in class Object