Mongodb upsert抛出DuplicateKeyException

当我尝试使用方法[1]插入(增加或插入)文档时,我不时会收到此错误[2].

[1]

public NGram save(final NGram ngram) {
    Criteria cr = where("_id").is(ngram.getNgram())
            .and("f3c").is(ngram.getF3c())
            .and("tokCount").is(ngram.getTokCount())
            .and("first").is(ngram.getFirst())
            ;
    if( ngram.getTokCount() > 1 ) {
        cr.and("second").is(ngram.getSecond());
    }
    if( ngram.getTokCount() > 2 ) {
        cr.and("third").is(ngram.getThird());
    }
    final Query qry = new Query( cr );
    final Update updt = new Update().inc("count", ngram.getCount());
    template.upsert(qry, updt, NGram.class);
    return ngram;
}

[2]

Caused by: org.springframework.dao.DuplicateKeyException: E11000 duplicate key error index: sytrue.ngram.$_id_  dup key: { : "page two" }; nested exception is com.mongodb.MongoException$DuplicateKey: E11000 duplicate key error index: sytrue.ngram.$_id_  dup key: { : "page two" }
at org.springframework.data.mongodb.core.MongoExceptionTranslator.translateExceptionIfPossible(MongoExceptionTranslator.java:52)
at org.springframework.data.mongodb.core.MongoTemplate.potentiallyConvertRuntimeException(MongoTemplate.java:1665)
at org.springframework.data.mongodb.core.MongoTemplate.execute(MongoTemplate.java:390)
at org.springframework.data.mongodb.core.MongoTemplate.doUpdate(MongoTemplate.java:920)
at org.springframework.data.mongodb.core.MongoTemplate.upsert(MongoTemplate.java:894)
at com.sytrue.ngram.repo.impl.NGramRepositoryImpl.save(NGramRepositoryImpl.java:43)
at sun.reflect.GeneratedMethodAccessor41.invoke(Unknown Source)

Upsert永远不会给我这个例外.我对吗？

我猜的问题可能是:

您正在根据许多标准进行查找操作.这意味着如果由于param(在标准中)的任何不匹配而失败,那么它将尝试插入文档.

因此,很有可能,您尝试使用相同的_id更新同一文档,但其他一些条件不匹配,导致它再次插入,这将导致重复键异常.考虑下面的例子

test:Mongo > db.example.update({ _id : 1, a : 1, b : 1},{ $set : {d : 1}}, true, false)
test:Mongo > db.example.find()
{ "_id" : 1, "a" : 1, "b" : 1, "d" : 1 }
test:Mongo > db.example.update({ _id : 1, a : 1, b : 2},{ $set : {d : 1}}, true, false)
E11000 duplicate key error index: test.example.$_id_  dup key: { : 1.0 }