原文鏈接：http://blog.csdn.net/z634075513/article/details/51554194

工作中使用到了Oracle12的版本，使用hibernate5保存時發現生成的結果除了1正常其余的都從-49開始往上加，

數據庫自身查詢是沒有問題的。

跟蹤hibernate5的源碼發現@SequenceGenerator還需要配置一個allocationSize=1才能正常

如

@SequenceGenerator(name="UMS_USER_SEQ", sequenceName="UMS_USER_SEQ",allocationSize = 1)

相關源碼在org.hibernate.id.enhanced.PooledOptimizer#generat

generationState.value = callback.getNextValue();			// unfortunately not really safe to normalize this			// to 1 as an initial value like we do the others			// because we would not be able to control this if			// we are using a sequence...			if ( generationState.value.lt( 1 ) ) {				log.pooledOptimizerReportedInitialValue( generationState.value );			}			// the call to obtain next-value just gave us the initialValue			if ( ( initialValue == -1					&& generationState.value.lt( incrementSize ) )					|| generationState.value.eq( initialValue ) ) {				generationState.hiValue = callback.getNextValue();			}			else {				generationState.hiValue = generationState.value;				generationState.value = generationState.hiValue.copy().subtract( incrementSize - 1 );			}
問題:
1.有如下sequenceGenerator,用的哪個?
sequenceGenerator: (sequenceHiLoGenerator, sequenceIdentityGenerator)
sequenceStyleGenerator
2.有如下Optimizer, 用的哪個?
PooledOptimizer/PooledLoOptimizer/HiLoOptimizer/LegacyHiLoAlgorithmOptimizer()/NoopOptimizer;