我用这种文件创建了一个集合:
{
"Date": 1481673600,
"Name": "Test"
"DailyCurve": [
{
"TimeStamp": 1481673600,
"ACPower": 0,
"DCPower": 0
},
{
"TimeStamp": 1481716800,
"ACPower": 30.599999999999998,
"DCPower": 0
},
{
"TimeStamp": 1481717700,
"ACPower": 50.099999999999994,
"DCPower": 0
},
{
"TimeStamp": 1481718600,
"ACPower": 46.6,
"DCPower": 0
},
]
}
因为我想查询大量数据,我想使用投影来减少所需的RU。
我理解,例如,如果我只需要Date
值,我只需使用此查询:
SELECT c.Date FROM c
但是现在我还要将子文档投影到DailyCurve
属性下。
要收到我可以使用的全套:
SELECT c.Date, c.DailyCurve FROM c
但是,我必须做什么才能收到TimeStamp
和ACPower
值?
我想要创建的结果应如下所示:
[{
"Date": 1481673600,
"DailyCurve": [
{
"TimeStamp": 1481673600,
"ACPower": 0,
},
{
"TimeStamp": 1481716800,
"ACPower": 30.599999999999998,
},
{
"TimeStamp": 1481717700,
"ACPower": 50.099999999999994,
},
{
"TimeStamp": 1481718600,
"ACPower": 46.6,
},
]
},
...]
答案 0 :(得分:1)
您需要用户定义的功能才能执行此操作。首先,为这样的项目注册一个UDF:
function project(document) {
var result = {};
result["Date"] = document["Date"];
result["DailyCurve"] = [];
var dailyCurve = document["DailyCurve"];
for (var idx in dailyCurve) {
var elem = dailyCurve[idx];
result["DailyCurve"].push(
{ "TimeStamp": elem["TimeStamp"],
"ACPower": elem["ACPower"]});
}
return result;
}
然后在DocumentDB查询中使用它,如:
SELECT udf.project(c) FROM c
如果您希望在DocumentDB中看到对子查询投影的原生支持(不需要UDF),请在此处提出/ upvote:https://feedback.azure.com/forums/263030-documentdb