In my current project we are using PostgreSQL as DB and Spring data JPA for persistence. In all entity classes we are using GenerationType.SEQUENCE for generation of primary key value. It's working fine. But, the value for the primary key in each table not starting from 1 . The value is always next increment value of the maximum number of other table's primary key.
How can we change this ? . How to make primary key value of each table should start from 1.
You need to configure a sequence per table. This answer explains how to do that.
I'm just quoting it here:
Contents of my package-info.java:
#GenericGenerator(
name = "optimized-sequence",
strategy = "enhanced-sequence",
parameters = {
#Parameter(name="prefer_sequence_per_entity", value="true"),
#Parameter(name="optimizer", value="hilo"),
#Parameter(name="increment_size", value="50")})
package org.example.model;
import org.hibernate.annotations.GenericGenerator;
import org.hibernate.annotations.Parameter;
On the usage side you just need
#Id #GeneratedValue(generator="optimized-sequence")
public long id;
Below code on ID worked for me.
#Id
#SequenceGenerator(name = "MY_ENTITY_SEQ", sequenceName = "MY_ENTITY_SEQ", allocationSize=1)
#GeneratedValue(strategy = GenerationType.AUTO, generator = "MY_ENTITY_SEQ" )
#Column(updatable = false, nullable = false)
private Integer id;
Please let me know if i face any issues with this approach in future.
Related
My application is using JPA for persisting data to Database.
The application has to generate Custom(encoded) sequence for performance reasons.
By default JPA seems to generate Ids for an entity using some sequence.
How to override default sequence generator with customer sequence generator in Java ? I want to have sequence generator in Java as I have a separate logic for that.
This is how you go with the custom sequence:
#Id
#SequenceGenerator(name = "pet_seq",
sequenceName = "pet_sequence",
initialValue = 1, allocationSize = 20)
#GeneratedValue(strategy = GenerationType.SEQUENCE, generator = "pet_seq")
#Column(name = "id", nullable = false)
private Long id;
In this case it will use pet_sequence instead of the default one. Also you can read this article for a better understanding of this subject.
I have the following entity and their mapping
#Entity
#Table(name = "test")
public class Test implements Serializable {
private static final long serialVersionUID = 1L;
#Id
#GeneratedValue(strategy = GenerationType.SEQUENCE, generator = "sequenceGenerator")
#SequenceGenerator(name = "sequenceGenerator", initialValue = 20000)
I want id value begins in 20000 but it doesn't work in postgresql. When the application starts I receive this exception
Caused by: org.hibernate.HibernateException: Multiple references to
database sequence [sequence_generator] were encountered attempting to
set conflicting values for 'initial value'. Fou nd [20000] and [1]
Do I need a extra configuration to it works?
PS: It is a new database without any previous configuration
You could try #TableGenerator annotation. Initial values can be set and seed other values.
You can find example and documentation here:
Set Initial Value Of Table Generator
I am new to Postgres database.
I have a Java Entity class with the below column for ID:
#Entity
#Table(name = "THE_RULES")
public class TheRulesEntity {
/** The id. */
#Column(name = "TEST_NO", precision = 8)
#SequenceGenerator(name = "test_no_seq", sequenceName = "TEST_NO_SEQ")
#GeneratedValue(generator = "test_no_seq", strategy = GenerationType.AUTO)
#Id
private Long id;
/** The test val. */
#Column(name = "TEST_VAL", nullable = false, length = 3)
private String testVal;
Code:
rulesRepository.saveAndFlush(theRulesEntity)
Table:
CREATE TABLE THE_RULES
(
TEST_NO INT NOT NULL,
TEST_VAL VARCHAR(3) NOT NULL
)
CREATE SEQUENCE "TEST_NO_SEQ" START WITH 1000 INCREMENT BY 1;
When I try to insert a new record into the postgres database from my application (the ID value is null in Java code during Debug mode), then I get the below error:
Caused by: org.postgresql.util.PSQLException: ERROR: relation "dual" does not exist
But If I insert the record manually into database table and then update the record from my application, then the record is updated successfully (Probably because the application uses the same ID value so no need to refer to the Sequence TEST_NO_SEQ value anymore)
Looks like the database is not able to access the sequence from dual table.
Could anyone help me how to fix this?
Thanks.
Thanks to Joop and a_horse_with_no_name, the issue is resolved
I have used Oracle driver which is wrong. I have updated my code to use Postgres driver
I created the Sequence again in the database with same name but without the Quotes
I used all capital-case letters in my Java entity class to refer to the sequence correctly
i have prob with mapping sequence auto increment
#GeneratedValue(strategy=GenerationType.SEQUENCE)
i'm using on sql developer it work but when i try on netbeans i get the message
Caused by: java.lang.NullPointerException
Create a sequence named SOME_SEQ in your db for this particular table. And use the annotations above your id field. allocationSize=1 means increment the value by 1. And some_seq_gen_name is for unique labeling.
#Id
#Column(name = "id")
#GeneratedValue(generator="some_seq_gen_name")
#SequenceGenerator(name="some_seq_gen_name", sequenceName="SOME_SEQ", allocationSize=1)
private Long id;
UPDATE: Based on your comment, for commit try this one:
EntityTransaction et = em.getTransaction();
et.begin();
// write persist code here
et.commit();
I am attempting to persist an entity with an attribute that I want to be populated from a DB sequence. I'm using Oracle, have created the sequence, verified the sequence works via sql, and yet my attribute isn't getting populated. Here's what I have:
#GeneratedValue(generator = "RFQ_LINE_IDS_SEQUENCE", strategy=GenerationType.SEQUENCE)
#SequenceGenerator(name="RFQ_LINE_IDS_SEQUENCE", sequenceName="RFQ_LINE_IDS_SEQUENCE", allocationSize=1000000000)
#Column(name = "external_line_item_id")
private String externalLineItemId;
All the examples I'm seen online show this annotation being used with #Id, but I have another attribute that I'm using for my id.
I've also tried the following to no avail:
#GeneratedValue(generator = "RFQ_LINE_IDS_SEQUENCE", strategy=GenerationType.SEQUENCE)
#GenericGenerator(name = "RFQ_LINE_IDS_SEQUENCE", strategy = "sequence",
parameters = {#Parameter(name = "sequence", value = "RFQ_LINE_IDS_SEQUENCE")})
#Column(name = "external_line_item_id")
private String externalLineItemId;
JPA only mandates support for #GeneratedValue on #Id fields. Some JPA implementations (such as DataNucleus JPA) support it but not all do.
I have created a proposal for JPA to support #GeneratedValue for non-id attributes. Please vote here for this to be included in 2.2
https://java.net/jira/browse/JPA_SPEC-113