What are the possible values of the Hibernate hbm2ddl auto configuration and what do they do

Question

I really want to know more about the update  export and the values that could be given to hibernate hbm2ddl auto I need to know when to use the update and when not  And what is the alternative   These are changes that could happen over DB    new tables new columns in old tables columns deleted data type of a column changed a type of a column changed its attributes tables dropped values of a column changed    In each case what is the best solution

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I Think you should have to concentrate on the   SchemaExport Class    this Class Makes Your Configuration Dynamic  So it allows you to choose whatever suites you best     Checkout  SchemaExport

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To whomever searching for default value    It is written in the source code at version 2 0 5 of spring-boot and 1 1 0 at JpaProperties                 DDL mode  This is actually a shortcut for the  quot hibernate hbm2ddl auto quot         property  Defaults to  quot create-drop quot  when using an embedded database and no        schema manager was detected  Otherwise  defaults to  quot none quot               private String ddlAuto

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Although it is quite an old post but as i did some research on the topic so thought of sharing it   hibernate hbm2ddl auto  As per the documentation it can have four valid values   create     update     validate     create-drop  Following is the explanation of the behaviour shown by these value    create  - create the schema  the data previously present  if there  in the schema is lost update - update the schema with the given values  validate - validate the schema  It makes no change in the DB  create-drop - create the schema with destroying the data previously present if there   It also drop the database schema when the SessionFactory is closed    Following are the important points worth noting    In case of update  if schema is not present in the DB then the schema is created  In case of validate  if schema does not exists in DB  it is not created  Instead  it will throw an error - Table not found  lt table name gt  In case of create-drop  schema is not dropped on closing the session  It drops only on closing the SessionFactory  In case if i give any value to this property say abc  instead of above four values discussed above  or it is just left blank  It shows following behaviour   -If schema is not present in the DB - It creates the schema  -If schema is present in the DB - update the schema

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Since 5 0  you can now find those values in a dedicated Enum  org hibernate boot SchemaAutoTooling  enhanced with value NONE since 5 2    Or even better  since 5 1  you can also use the org hibernate tool schema Action Enum which combines JPA 2 and  legacy  Hibernate DDL actions   But  you cannot yet configure a DataSource programmatically with this  It would be nicer to use this combined with org hibernate cfg AvailableSettings HBM2DDL AUTO but the current code expect a String value  excerpt taken from SessionFactoryBuilderImpl    this schemaAutoTooling   SchemaAutoTooling interpret   String  configurationSettings get  AvailableSettings HBM2DDL AUTO            and internal enum values of both org hibernate boot SchemaAutoToolingand org hibernate tool schema Action aren t exposed publicly   Hereunder  a sample programmatic DataSource configuration  used in ones of my Spring Boot applications  which use a gambit thanks to  name   toLowerCase   but it only works with values without dash  not create-drop for instance     Bean name   ENTITY MANAGER NAME  public LocalContainerEntityManagerFactoryBean internalEntityManagerFactory          EntityManagerFactoryBuilder builder           Qualifier DATA SOURCE NAME  DataSource internalDataSource         Map lt String  Object gt  properties   new HashMap lt  gt         properties put AvailableSettings HBM2DDL AUTO  SchemaAutoTooling CREATE name   toLowerCase         properties put AvailableSettings DIALECT  H2Dialect class getName          return builder              dataSource internalDataSource               packages JpaModelsScanEntry class  Jsr310JpaConverters class               persistenceUnit PERSISTENCE UNIT NAME               properties properties               build

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First  the possible values for the hbm2ddl configuration property are the following ones   none - No action is performed  The schema will not be generated  create-only - The database schema will be generated  drop - The database schema will be dropped  create - The database schema will be dropped and created afterward  create-drop - The database schema will be dropped and created afterward  Upon closing the SessionFactory  the database schema will be dropped  validate - The database schema will be validated using the entity mappings  update - The database schema will be updated by comparing the existing database schema with the entity mappings   The hibernate hbm2ddl auto  quot update quot  is convenient but less flexible if you plan on adding functions or executing some custom scripts  So  The most flexible approach is to use Flyway  However  even if you use Flyway  you can still generate the initial migration script using hbm2ddl

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The configuration property is called hibernate hbm2ddl auto  In our development environment we set hibernate hbm2ddl auto create-drop to drop and create a clean database each time we deploy  so that our database is in a known state   In theory  you can set hibernate hbm2ddl auto update to update your database with changes to your model  but I would not trust that on a production database  An earlier version of the documentation said that this was experimental  at least  I do not know the current status   Therefore  for our production database  do not set hibernate hbm2ddl auto - the default is to make no database changes  Instead  we manually create an SQL DDL update script that applies changes from one version to the next

User · Answer

I Think you should have to concentrate on the   SchemaExport Class    this Class Makes Your Configuration Dynamic  So it allows you to choose whatever suites you best     Checkout  SchemaExport

User · Answer

Since 5 0  you can now find those values in a dedicated Enum  org hibernate boot SchemaAutoTooling  enhanced with value NONE since 5 2    Or even better  since 5 1  you can also use the org hibernate tool schema Action Enum which combines JPA 2 and  legacy  Hibernate DDL actions   But  you cannot yet configure a DataSource programmatically with this  It would be nicer to use this combined with org hibernate cfg AvailableSettings HBM2DDL AUTO but the current code expect a String value  excerpt taken from SessionFactoryBuilderImpl    this schemaAutoTooling   SchemaAutoTooling interpret   String  configurationSettings get  AvailableSettings HBM2DDL AUTO            and internal enum values of both org hibernate boot SchemaAutoToolingand org hibernate tool schema Action aren t exposed publicly   Hereunder  a sample programmatic DataSource configuration  used in ones of my Spring Boot applications  which use a gambit thanks to  name   toLowerCase   but it only works with values without dash  not create-drop for instance     Bean name   ENTITY MANAGER NAME  public LocalContainerEntityManagerFactoryBean internalEntityManagerFactory          EntityManagerFactoryBuilder builder           Qualifier DATA SOURCE NAME  DataSource internalDataSource         Map lt String  Object gt  properties   new HashMap lt  gt         properties put AvailableSettings HBM2DDL AUTO  SchemaAutoTooling CREATE name   toLowerCase         properties put AvailableSettings DIALECT  H2Dialect class getName          return builder              dataSource internalDataSource               packages JpaModelsScanEntry class  Jsr310JpaConverters class               persistenceUnit PERSISTENCE UNIT NAME               properties properties               build

User · Answer

The configuration property is called hibernate hbm2ddl auto  In our development environment we set hibernate hbm2ddl auto create-drop to drop and create a clean database each time we deploy  so that our database is in a known state   In theory  you can set hibernate hbm2ddl auto update to update your database with changes to your model  but I would not trust that on a production database  An earlier version of the documentation said that this was experimental  at least  I do not know the current status   Therefore  for our production database  do not set hibernate hbm2ddl auto - the default is to make no database changes  Instead  we manually create an SQL DDL update script that applies changes from one version to the next

User · Answer

validate  validates the schema  no change happens to the database  update  updates the schema with current execute query  create  creates new schema every time  and destroys previous data  create-drop  drops the schema when the application is stopped or SessionFactory is closed explicitly

User · Answer

To whomever searching for default value    It is written in the source code at version 2 0 5 of spring-boot and 1 1 0 at JpaProperties                 DDL mode  This is actually a shortcut for the  quot hibernate hbm2ddl auto quot         property  Defaults to  quot create-drop quot  when using an embedded database and no        schema manager was detected  Otherwise  defaults to  quot none quot               private String ddlAuto

User · Answer

If you don t want to use Strings in your app and are looking for predefined constants have a look at org hibernate cfg AvailableSettings class included in the Hibernate JAR  where you ll find a constant for all possible settings  In your case for example          Auto export update schema using hbm2ddl tool  Valid values are  lt tt gt update lt  tt gt       lt tt gt create lt  tt gt    lt tt gt create-drop lt  tt gt  and  lt tt gt validate lt  tt gt       String HBM2DDL AUTO    hibernate hbm2ddl auto

User · Answer

First  the possible values for the hbm2ddl configuration property are the following ones   none - No action is performed  The schema will not be generated  create-only - The database schema will be generated  drop - The database schema will be dropped  create - The database schema will be dropped and created afterward  create-drop - The database schema will be dropped and created afterward  Upon closing the SessionFactory  the database schema will be dropped  validate - The database schema will be validated using the entity mappings  update - The database schema will be updated by comparing the existing database schema with the entity mappings   The hibernate hbm2ddl auto  quot update quot  is convenient but less flexible if you plan on adding functions or executing some custom scripts  So  The most flexible approach is to use Flyway  However  even if you use Flyway  you can still generate the initial migration script using hbm2ddl

User · Answer

The configuration property is called hibernate hbm2ddl auto  In our development environment we set hibernate hbm2ddl auto create-drop to drop and create a clean database each time we deploy  so that our database is in a known state   In theory  you can set hibernate hbm2ddl auto update to update your database with changes to your model  but I would not trust that on a production database  An earlier version of the documentation said that this was experimental  at least  I do not know the current status   Therefore  for our production database  do not set hibernate hbm2ddl auto - the default is to make no database changes  Instead  we manually create an SQL DDL update script that applies changes from one version to the next

User · Answer

validate  It validates the schema and makes no changes to the DB  Assume you have added a new column in the mapping file and perform the insert operation  it will throw an Exception  missing the XYZ column  because the existing schema is different than the object you are going to insert  If you alter the table by adding that new column manually then perform the Insert operation then it will definitely insert all columns along with the new column to the Table  Means it doesn t make any changes alters the existing schema table   update  it alters the existing table in the database when you perform operation   You can add or remove columns with this option of hbm2ddl   But if you are going to add a new column that is  NOT NULL  then it will ignore adding that particular column to the DB  Because the Table must be empty if you want to add a  NOT NULL  column to the existing table

User · Answer

If you don t want to use Strings in your app and are looking for predefined constants have a look at org hibernate cfg AvailableSettings class included in the Hibernate JAR  where you ll find a constant for all possible settings  In your case for example          Auto export update schema using hbm2ddl tool  Valid values are  lt tt gt update lt  tt gt       lt tt gt create lt  tt gt    lt tt gt create-drop lt  tt gt  and  lt tt gt validate lt  tt gt       String HBM2DDL AUTO    hibernate hbm2ddl auto

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There s also the undocumented value of  none  to disable it entirely

User · Answer

From the community documentation   hibernate hbm2ddl auto    Automatically validates or exports schema DDL to the database when the SessionFactory is created  With create-drop  the database schema will be dropped when the SessionFactory is closed explicitly  e g  validate   update   create   create-drop  So the list of possible options are   validate  validate the schema  makes no changes to the database  update  update the schema  create  creates the schema  destroying previous data  create-drop  drop the schema when the SessionFactory is closed explicitly  typically when the application is stopped  none  does nothing with the schema  makes no changes to the database  These options seem intended to be developers tools and not to facilitate any production level databases  you may want to have a look at the following question  Hibernate  hbm2ddl auto update in production

User · Answer

hibernate hbm2ddl auto automatically validates and exports DDL to the schema when the sessionFactory is created   By default  it does not perform any creation or modification automatically on DB  If the user sets one of the below values then it is doing DDL schema changes automatically    create - doing creating a schema   lt entry key  hibernate hbm2ddl auto  value  create  gt   update - updating existing schema   lt entry key  hibernate hbm2ddl auto  value  update  gt   validate - validate existing schema   lt entry key  hibernate hbm2ddl auto  value  validate  gt   create-drop - create and drop the schema automatically when a session is starts and ends   lt entry key  hibernate hbm2ddl auto  value  create-drop  gt

User · Answer

validate  It validates the schema and makes no changes to the DB  Assume you have added a new column in the mapping file and perform the insert operation  it will throw an Exception  missing the XYZ column  because the existing schema is different than the object you are going to insert  If you alter the table by adding that new column manually then perform the Insert operation then it will definitely insert all columns along with the new column to the Table  Means it doesn t make any changes alters the existing schema table   update  it alters the existing table in the database when you perform operation   You can add or remove columns with this option of hbm2ddl   But if you are going to add a new column that is  NOT NULL  then it will ignore adding that particular column to the DB  Because the Table must be empty if you want to add a  NOT NULL  column to the existing table

User · Answer

I would use liquibase for updating your db  hibernate s schema update feature is really only o k  for a developer while they are developing new features  In a production situation  the db upgrade needs to be handled more carefully

User · Answer

The configuration property is called hibernate hbm2ddl auto  In our development environment we set hibernate hbm2ddl auto create-drop to drop and create a clean database each time we deploy  so that our database is in a known state   In theory  you can set hibernate hbm2ddl auto update to update your database with changes to your model  but I would not trust that on a production database  An earlier version of the documentation said that this was experimental  at least  I do not know the current status   Therefore  for our production database  do not set hibernate hbm2ddl auto - the default is to make no database changes  Instead  we manually create an SQL DDL update script that applies changes from one version to the next

User · Answer

From the community documentation   hibernate hbm2ddl auto    Automatically validates or exports schema DDL to the database when the SessionFactory is created  With create-drop  the database schema will be dropped when the SessionFactory is closed explicitly  e g  validate   update   create   create-drop  So the list of possible options are   validate  validate the schema  makes no changes to the database  update  update the schema  create  creates the schema  destroying previous data  create-drop  drop the schema when the SessionFactory is closed explicitly  typically when the application is stopped  none  does nothing with the schema  makes no changes to the database  These options seem intended to be developers tools and not to facilitate any production level databases  you may want to have a look at the following question  Hibernate  hbm2ddl auto update in production

User · Answer

I would use liquibase for updating your db  hibernate s schema update feature is really only o k  for a developer while they are developing new features  In a production situation  the db upgrade needs to be handled more carefully

User · Answer

There s also the undocumented value of  none  to disable it entirely

User · Answer

Although it is quite an old post but as i did some research on the topic so thought of sharing it   hibernate hbm2ddl auto  As per the documentation it can have four valid values   create     update     validate     create-drop  Following is the explanation of the behaviour shown by these value    create  - create the schema  the data previously present  if there  in the schema is lost update - update the schema with the given values  validate - validate the schema  It makes no change in the DB  create-drop - create the schema with destroying the data previously present if there   It also drop the database schema when the SessionFactory is closed    Following are the important points worth noting    In case of update  if schema is not present in the DB then the schema is created  In case of validate  if schema does not exists in DB  it is not created  Instead  it will throw an error - Table not found  lt table name gt  In case of create-drop  schema is not dropped on closing the session  It drops only on closing the SessionFactory  In case if i give any value to this property say abc  instead of above four values discussed above  or it is just left blank  It shows following behaviour   -If schema is not present in the DB - It creates the schema  -If schema is present in the DB - update the schema

User · Answer

validate  validates the schema  no change happens to the database  update  updates the schema with current execute query  create  creates new schema every time  and destroys previous data  create-drop  drops the schema when the application is stopped or SessionFactory is closed explicitly

User · Answer

hibernate hbm2ddl auto automatically validates and exports DDL to the schema when the sessionFactory is created   By default  it does not perform any creation or modification automatically on DB  If the user sets one of the below values then it is doing DDL schema changes automatically    create - doing creating a schema   lt entry key  hibernate hbm2ddl auto  value  create  gt   update - updating existing schema   lt entry key  hibernate hbm2ddl auto  value  update  gt   validate - validate existing schema   lt entry key  hibernate hbm2ddl auto  value  validate  gt   create-drop - create and drop the schema automatically when a session is starts and ends   lt entry key  hibernate hbm2ddl auto  value  create-drop  gt

[java] What are the possible values of the Hibernate hbm2ddl.auto configuration and what do they do

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