Mapreduce 按日期分组的RavenDB映射/缩减
我必须创建一个查询,以获得每年/每月的邮寄统计数据,例如按日期分组。我创建了一个索引:Mapreduce 按日期分组的RavenDB映射/缩减,mapreduce,ravendb,Mapreduce,Ravendb,我必须创建一个查询,以获得每年/每月的邮寄统计数据,例如按日期分组。我创建了一个索引: public class Posts_Count : AbstractIndexCreationTask<Post, ArchiveItem> { public Posts_Count() { Map = posts => from post in posts select new
public class Posts_Count : AbstractIndexCreationTask<Post, ArchiveItem>
{
public Posts_Count()
{
Map = posts => from post in posts
select new
{
Year = post.PublishedOn.Year,
Month = post.PublishedOn.Month,
Count = 1
};
Reduce = results => from result in results
group result by new {
result.Year,
result.Month
}
into agg
select new
{
Year = agg.Key.Year,
Month = agg.Key.Month,
Count = agg.Sum(x => x.Count)
};
}
}
减少:
results
.GroupBy(result => new {Year = result.Year, Month = result.Month})
.Select(agg => new {Year = agg.Key.Year, Month = agg.Key.Month, Count = agg.Sum(x => ((System.Int32)(x.Count)))})
但问题是我总是得到一个空值的年份和月份属性:
{
"Year": null,
"Month": null,
"Count": "1"
}
有人能帮我用代码解决这个问题吗?谢谢大家! 您的代码看起来不错。我测试了它,它在当前不稳定的版本1.2.2096中工作。最近,RavenDB谷歌集团对此进行了一些讨论,因此,也许它之前已经被打破了。请使用当前版本再试一次,看看它现在是否适合您。hmm,上面的索引看起来不错,但我们是否需要为每个项目定义排序选项?例如
Sort(x=>x.Year,SortOptions.Int);排序(x=>x.Month,SortOptions.Int);排序(x=>x.Count,SortOptions.Int)代码>?否则,我们不会得到排序不一致的结果吗?
{
"Year": null,
"Month": null,
"Count": "1"
}