Azure DocumentDB子文档投影
我用这种文档创建了一个集合:Azure DocumentDB子文档投影,azure,azure-cosmosdb,Azure,Azure Cosmosdb,我用这种文档创建了一个集合: { "Date": 1481673600, "Name": "Test" "DailyCurve": [ { "TimeStamp": 1481673600, "ACPower": 0, "DCPower": 0 }, { "TimeStamp": 1481716800, "ACPower": 30
{
"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,所以我想使用投影来减少所需的RU
例如,我知道如果我只需要日期
值,我只需使用以下查询:
SELECT c.Date FROM c
但现在我还想将子文档投影到DailyCurve
属性下
要接收全套,我可以使用:
SELECT c.Date, c.DailyCurve FROM c
但是我必须做什么才能只接收时间戳
和ACPower
值呢
我要创建的结果应该如下所示:
[{
"Date": 1481673600,
"DailyCurve": [
{
"TimeStamp": 1481673600,
"ACPower": 0,
},
{
"TimeStamp": 1481716800,
"ACPower": 30.599999999999998,
},
{
"TimeStamp": 1481717700,
"ACPower": 50.099999999999994,
},
{
"TimeStamp": 1481718600,
"ACPower": 46.6,
},
]
},
...]
要做到这一点,您需要用户定义的函数。首先,为如下项目注册一个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中看到对子查询预测的本机支持(不需要UDF),请在此处提出建议/upvote:谢谢Microsoft的Aravind:)我创建了一个建议