BatchSequenceGenerator (hibernate-types-43 2.17.0 API)

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com.vladmihalcea.hibernate.id
Class BatchSequenceGenerator

java.lang.Object
  com.vladmihalcea.hibernate.id.BatchSequenceGenerator

All Implemented Interfaces:: 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
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
`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
`BatchSequenceGenerator()`

Method Summary
`void`	`configure(org.hibernate.type.Type type, Properties params, org.hibernate.dialect.Dialect dialect)`
`String`	`determineBulkInsertionIdentifierGenerationSelectFragment(org.hibernate.dialect.Dialect dialect)`
`Serializable`	`generate(org.hibernate.engine.spi.SessionImplementor session, Object object)`
`Object`	`generatorKey()`
`String[]`	`sqlCreateStrings(org.hibernate.dialect.Dialect dialect)` Deprecated.
`String[]`	`sqlDropStrings(org.hibernate.dialect.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