例如,我的收藏中有以下文档:
{
"_id" : "GuqXmAkkARqhBDqhy",
"beatmapset_id" : "342537",
"version" : "MX",
"diff_approach" : "5",
"artist" : "Yousei Teikoku",
"title" : "Kokou no Sousei",
"difficultyrating" : "3.5552737712860107"
}
{
"_id" : "oHLT7KqsB7bztBGvu",
"beatmapset_id" : "342537",
"version" : "HD",
"diff_approach" : "5",
"artist" : "Yousei Teikoku",
"title" : "Kokou no Sousei",
"difficultyrating" : "2.7515676021575928"
}
{
"_id" : "GbotZfrPEwW69FkGD",
"beatmapset_id" : "342537",
"version" : "NM",
"diff_approach" : "5",
"artist" : "Yousei Teikoku",
"title" : "Kokou no Sousei",
"difficultyrating" : "0"
}
这些文件具有相同的密钥beatmapset_id
我想删除所有重复项,但保留最多的文档difficultyrating
.
I tried db.collection.ensureIndex({beatmapset_id: 1}, {unique: true, dropDups: true})
但它留下了一个随机文件,我想要上面的条件。
我怎样才能做到这一点?