红帽全球峰会7.6.2. 从索引中删除实例
可以从 Lucene 索引中删除给定类型的实体或所有实体，而无需将它们从数据库中物理删除。此操作名为清除，也通过 FullTextSession 进行。
清除操作允许从 Lucene 索引中删除单个实体或指定类型的所有实体，而无需将它们从数据库中物理删除。此操作使用 FullTextSession 来执行。
示例：从索引中清除实体的特定实例
FullTextSession fullTextSession = Search.getFullTextSession(session);
Transaction tx = fullTextSession.beginTransaction();
for (Customer customer : customers) {
fullTextSession.purgeAll( Customer.class );
//optionally optimize the index
//fullTextSession.getSearchFactory().optimize( Customer.class );
tx.commit(); //index is updated at commit time建议在此类操作后优化索引。
注意
FullTextEntityManager 上也提供方法索引、清除和清除All。
注意
所有手动索引方法（index、purge 和 purgeAll）都只会影响索引，而不是数据库，但是在事务成功提交或您使用 flushToIndexes 之前不会应用它们。
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