如何在CouchDB中执行SQL等效的"DISTINCT"？

Question

我在CouchDB中有一堆MP3元数据.我想返回MP3元数据中的每张专辑,但没有重复.

典型文档如下所示:

{
   "_id": "005e16a055ba78589695c583fbcdf7e26064df98",
   "_rev": "2-87aa12c52ee0a406084b09eca6116804",
   "name": "Fifty-Fifty Clown",
   "number": 15,
   "artist": "Cocteau Twins",
   "bitrate": 320,
   "album": "Stars and Topsoil: A Collection (1982-1990)",
   "path": "Cocteau Twins/Stars and Topsoil: A Collection (1982-1990)/15 - Fifty-Fifty Clown.mp3",
   "year": 0,
   "genre": "Shoegaze"
}

Answer 1

我相信你的map/reduce看起来像:

function map(doc) {
    emit(doc.album, null);
}

function reduce(key, values) {
    return null;
}

请记住使用额外参数进行查询 group=true

Answer 2

看一看查看食谱为SQL骑师 获取独特价值部分.