hibernate - @GeneratedValue(strategy="IDENTITY") vs. @GeneratedValue(strategy="SEQUENCE") -

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hibernate - @GeneratedValue(strategy="IDENTITY") vs. @GeneratedValue(strategy="SEQUENCE") -

i'm new hibernate. not understand the next 2 primary key generation strategies:

identity sequence

can please explain how these 2 work , difference between these two?

quoting java persistence/identity , sequencing:

identity sequencing uses special identity columns in database allow database automatically assign id object when row inserted. identity columns supported in many databases, such mysql, db2, sql server, sybase , postgres. oracle not back upwards identity columns can simulated through using sequence objects , triggers.

in plain english: mark @ 1 id column in table identity. database engine set next available value automatically.

and:

sequence objects utilize special database objects generate ids. sequence objects supported in databases, such oracle, db2, , postgres. usually, sequence object has name, increment, , other database object settings. each time <sequence>.nextval selected sequence incremented increment.

sequences more flexible , more complex. define object in database next tables, triggers, etc. called sequences. sequences named counter can utilize anywhere within queries.

hibernate jpa

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