Spring Data 1.3.0.RC1已发布,支持聚合框架。
例如:
shell聚合命令:
db.eft_transactions.aggregate(
{$match:
{
service:"EFT",
source:"MARKUP",
}
},
{$group:
{
_id:"$card_acceptor_id",
tran_count:{$sum:1},
amount_sum:{$sum:"$amount"}
}
}
)
这是从Java中运行的方式:
AggregationOperation match = Aggregation.match(Criteria.where("service").is("EFT").and("source").is("MARKUP"));
AggregationOperation group = Aggregation.group("card_acceptor").and("amount_sum").sum("amount").and("tran_count").count();
Aggregation aggregation = newAggregation(match, group);
AggregationResults<StoreSummary> result = this.mongoTemplate.aggregate(aggregation, "eft_transactions", StoreSummary.class);
文档在这里
注意:我们最近不得不切换到使用1.3.0版本的BUILD-SNAPSHOT构建。这个变化需要更改上述两行中的2个,它们已经更改为:
AggregationOperation group = Aggregation.group("card_acceptor").sum("amount").as("amount_sum").count().as("tran_count");
Aggregation aggregation = Aggregation.newAggregation(match, group);
sample
或随机选择怎么样?https://docs.mongodb.org/master/reference/operator/aggregation/sample/ - dieter