Reduce 不是按键计数

Question

我正在使用 couchbase 3.0 并使用啤酒样本数据。

我创建了一个视图，地图为：

function (doc, meta) {
  if (doc.category && doc.abv) {
    emit(doc.category, doc.abv);
  }
}

这给出了以下输出：

{"total_rows":2397,"rows":[
{"id":"21st_amendment_brewery_cafe-watermelon_wheat","key":"Belgian and French Ale","value":5.5},
{"id":"3_fonteinen_brouwerij_ambachtelijke_geuzestekerij-drie_fonteinen_kriek","key":"Belgian and French Ale","value":5},
{"id":"3_fonteinen_brouwerij_ambachtelijke_geuzestekerij-oude_geuze","key":"Belgian and French Ale","value":6},
{"id":"512_brewing_company-512_wit","key":"Belgian and French Ale","value":5.2},
{"id":"512_brewing_company-one","key":"Belgian and French Ale","value":8},
{"id":"abbaye_de_maredsous-10","key":"Belgian and French Ale","value":10},
{"id":"abbaye_de_maredsous-8","key":"Belgian and French Ale","value":8},
{"id":"abbaye_notre_dame_du_st_remy-rochefort_10","key":"Belgian and French Ale","value":11.3},
{"id":"abita_brewing_company-satsuma_harvest_wit","key":"Belgian and French Ale","value":5.1},
{"id":"affligem_brouwerij-affligem_dubbel","key":"Belgian and French Ale","value":6.8}
]
}

选择前 10 名时。

现在我想统计每个类别的啤酒数量。所以我决定添加内置的 reduce _count.

不幸的是，输出不是预期的，而是：

{"rows":[
 {"key":null,"value":2397}
 ]
}

为什么我将键设置为 null 而不是 doc.category？

Answer 1

我发现我在查询视图时忘记添加组参数了。有了它，一切正常。

Reduce 不是按键计数

Reduce is not counting by key

mapreduce

couchbase