在聚合期间围绕匹配查询对数据进行分区
Partition data around a match query during aggregation
我一直在努力解决的问题是在 mongo 查询中执行某种分区(按谓词拆分)。我当前的查询如下所示:
db.posts.aggregate([
{"$match": { $and:[ {$or:[{"toggled":false},{"toggled":true, "status":"INACTIVE"}]} , {"updatedAt":{$gte:1549786260000}} ] }},
{"$unwind" :"$interests"},
{"$group" : {"_id": {"iid": "$interests", "pid":"$publisher"}, "count": {"$sum" : 1}}},
{"$project":{ _id: 0, "iid": "$_id.iid", "pid": "$_id.pid", "count": 1 }}
])
这导致以下输出:
{
"count" : 3.0,
"iid" : "INT456",
"pid" : "P789"
}
{
"count" : 2.0,
"iid" : "INT789",
"pid" : "P789"
}
{
"count" : 1.0,
"iid" : "INT123",
"pid" : "P789"
}
{
"count" : 1.0,
"iid" : "INT123",
"pid" : "P123"
}
到目前为止一切正常,但后来我意识到对于匹配特定过滤器 {"toggled":true, "status":"INACTIVE"}
的文档,我宁愿 减少计数 (-1) . (考虑到最终值也可能是负数。)
有没有办法以某种方式在 match
之后对数据进行分区,以确保对两个文档集合执行不同的 grouping
操作?
听起来与我要找的相似的东西是
$mergeObjects
, or maybe $reduce
,但我无法从文档示例中了解多少。
注意:我能感觉到,处理这个问题的一种直接方法是执行两个查询,但我正在寻找执行操作的单个查询。
上述输出的示例文档为:
/* 1 */
{
"_id" : ObjectId("5d1f7******"),
"id" : "CON123",
"title" : "Game",
"content" : {},
"status" : "ACTIVE",
"toggle":false,
"publisher" : "P789",
"interests" : [
"INT456"
],
"updatedAt" : NumberLong(1582078628264)
}
/* 2 */
{
"_id" : ObjectId("5d1f8******"),
"id" : "CON456",
"title" : "Home",
"content" : {},
"status" : "INACTIVE",
"toggle":true,
"publisher" : "P789",
"interests" : [
"INT456",
"INT789"
],
"updatedAt" : NumberLong(1582078628264)
}
/* 3 */
{
"_id" : ObjectId("5d0e9******"),
"id" : "CON654",
"title" : "School",
"content" : {},
"status" : "ACTIVE",
"toggle":false,
"publisher" : "P789",
"interests" : [
"INT123",
"INT456",
"INT789"
],
"updatedAt" : NumberLong(1582078628264)
}
/* 4 */
{
"_id" : ObjectId("5d207*******"),
"id" : "CON789",
"title":"Stack",
"content" : { },
"status" : "ACTIVE",
"toggle":false,
"publisher" : "P123",
"interests" : [
"INT123"
],
"updatedAt" : NumberLong(1582078628264)
}
结果我期待的是
{
"count" : 1.0, (2-1)
"iid" : "INT456",
"pid" : "P789"
}
{
"count" : 0.0, (1-1)
"iid" : "INT789",
"pid" : "P789"
}
{
"count" : 1.0,
"iid" : "INT123",
"pid" : "P789"
}
{
"count" : 1.0,
"iid" : "INT123",
"pid" : "P123"
}
此聚合给出了预期的结果。
db.posts.aggregate( [
{ $match: { updatedAt: { $gte: 1549786260000 } } },
{ $facet: {
FALSE: [
{ $match: { toggle: false } },
{ $unwind : "$interests" },
{ $group : { _id : { iid: "$interests", pid: "$publisher" }, count: { $sum : 1 } } },
],
TRUE: [
{ $match: { toggle: true, status: "INACTIVE" } },
{ $unwind : "$interests" },
{ $group : { _id : { iid: "$interests", pid: "$publisher" }, count: { $sum : -1 } } },
]
} },
{ $project: { result: { $concatArrays: [ "$FALSE", "$TRUE" ] } } },
{ $unwind: "$result" },
{ $replaceRoot: { newRoot: "$result" } },
{ $group : { _id : "$_id", count: { $sum : "$count" } } },
{ $project:{ _id: 0, iid: "$_id.iid", pid: "$_id.pid", count: 1 } }
] )
[编辑添加]
使用问题 post 的输入数据的查询输出:
{ "count" : 1, "iid" : "INT123", "pid" : "P789" }
{ "count" : 1, "iid" : "INT123", "pid" : "P123" }
{ "count" : 0, "iid" : "INT789", "pid" : "P789" }
{ "count" : 1, "iid" : "INT456", "pid" : "P789" }
[编辑添加 2]
此查询使用不同的方法(代码)得到相同的结果:
db.posts.aggregate( [
{
$match: { updatedAt: { $gte: 1549786260000 } }
},
{
$unwind : "$interests"
},
{
$group : {
_id : {
iid: "$interests",
pid: "$publisher"
},
count: {
$sum: {
$switch: {
branches: [
{ case: { $eq: [ "$toggle", false ] },
then: 1 },
{ case: { $and: [ { $eq: [ "$toggle", true] }, { $eq: [ "$status", "INACTIVE" ] } ] },
then: -1 }
]
}
}
}
}
},
{
$project:{
_id: 0,
iid: "$_id.iid",
pid: "$_id.pid",
count: 1
}
}
] )
[编辑添加 3]
注意:
分面查询在同一组文档上运行两个分面(TRUE 和 FALSE);这就像两个并行查询 运行。但是,存在一些代码重复以及用于在管道中调整文档以获得所需输出的额外阶段。
第二个查询避免了代码重复,聚合管道中的阶段要少得多。当输入数据集有大量文档要处理时,这将在性能方面有所不同。一般来说,较少的阶段意味着较少的文档迭代(因为一个阶段必须扫描前一阶段输出的文档)。
我一直在努力解决的问题是在 mongo 查询中执行某种分区(按谓词拆分)。我当前的查询如下所示:
db.posts.aggregate([
{"$match": { $and:[ {$or:[{"toggled":false},{"toggled":true, "status":"INACTIVE"}]} , {"updatedAt":{$gte:1549786260000}} ] }},
{"$unwind" :"$interests"},
{"$group" : {"_id": {"iid": "$interests", "pid":"$publisher"}, "count": {"$sum" : 1}}},
{"$project":{ _id: 0, "iid": "$_id.iid", "pid": "$_id.pid", "count": 1 }}
])
这导致以下输出:
{
"count" : 3.0,
"iid" : "INT456",
"pid" : "P789"
}
{
"count" : 2.0,
"iid" : "INT789",
"pid" : "P789"
}
{
"count" : 1.0,
"iid" : "INT123",
"pid" : "P789"
}
{
"count" : 1.0,
"iid" : "INT123",
"pid" : "P123"
}
到目前为止一切正常,但后来我意识到对于匹配特定过滤器 {"toggled":true, "status":"INACTIVE"}
的文档,我宁愿 减少计数 (-1) . (考虑到最终值也可能是负数。)
有没有办法以某种方式在 match
之后对数据进行分区,以确保对两个文档集合执行不同的 grouping
操作?
听起来与我要找的相似的东西是
$mergeObjects
, or maybe $reduce
,但我无法从文档示例中了解多少。
注意:我能感觉到,处理这个问题的一种直接方法是执行两个查询,但我正在寻找执行操作的单个查询。
上述输出的示例文档为:
/* 1 */
{
"_id" : ObjectId("5d1f7******"),
"id" : "CON123",
"title" : "Game",
"content" : {},
"status" : "ACTIVE",
"toggle":false,
"publisher" : "P789",
"interests" : [
"INT456"
],
"updatedAt" : NumberLong(1582078628264)
}
/* 2 */
{
"_id" : ObjectId("5d1f8******"),
"id" : "CON456",
"title" : "Home",
"content" : {},
"status" : "INACTIVE",
"toggle":true,
"publisher" : "P789",
"interests" : [
"INT456",
"INT789"
],
"updatedAt" : NumberLong(1582078628264)
}
/* 3 */
{
"_id" : ObjectId("5d0e9******"),
"id" : "CON654",
"title" : "School",
"content" : {},
"status" : "ACTIVE",
"toggle":false,
"publisher" : "P789",
"interests" : [
"INT123",
"INT456",
"INT789"
],
"updatedAt" : NumberLong(1582078628264)
}
/* 4 */
{
"_id" : ObjectId("5d207*******"),
"id" : "CON789",
"title":"Stack",
"content" : { },
"status" : "ACTIVE",
"toggle":false,
"publisher" : "P123",
"interests" : [
"INT123"
],
"updatedAt" : NumberLong(1582078628264)
}
结果我期待的是
{
"count" : 1.0, (2-1)
"iid" : "INT456",
"pid" : "P789"
}
{
"count" : 0.0, (1-1)
"iid" : "INT789",
"pid" : "P789"
}
{
"count" : 1.0,
"iid" : "INT123",
"pid" : "P789"
}
{
"count" : 1.0,
"iid" : "INT123",
"pid" : "P123"
}
此聚合给出了预期的结果。
db.posts.aggregate( [
{ $match: { updatedAt: { $gte: 1549786260000 } } },
{ $facet: {
FALSE: [
{ $match: { toggle: false } },
{ $unwind : "$interests" },
{ $group : { _id : { iid: "$interests", pid: "$publisher" }, count: { $sum : 1 } } },
],
TRUE: [
{ $match: { toggle: true, status: "INACTIVE" } },
{ $unwind : "$interests" },
{ $group : { _id : { iid: "$interests", pid: "$publisher" }, count: { $sum : -1 } } },
]
} },
{ $project: { result: { $concatArrays: [ "$FALSE", "$TRUE" ] } } },
{ $unwind: "$result" },
{ $replaceRoot: { newRoot: "$result" } },
{ $group : { _id : "$_id", count: { $sum : "$count" } } },
{ $project:{ _id: 0, iid: "$_id.iid", pid: "$_id.pid", count: 1 } }
] )
[编辑添加]
使用问题 post 的输入数据的查询输出:
{ "count" : 1, "iid" : "INT123", "pid" : "P789" }
{ "count" : 1, "iid" : "INT123", "pid" : "P123" }
{ "count" : 0, "iid" : "INT789", "pid" : "P789" }
{ "count" : 1, "iid" : "INT456", "pid" : "P789" }
[编辑添加 2]
此查询使用不同的方法(代码)得到相同的结果:
db.posts.aggregate( [
{
$match: { updatedAt: { $gte: 1549786260000 } }
},
{
$unwind : "$interests"
},
{
$group : {
_id : {
iid: "$interests",
pid: "$publisher"
},
count: {
$sum: {
$switch: {
branches: [
{ case: { $eq: [ "$toggle", false ] },
then: 1 },
{ case: { $and: [ { $eq: [ "$toggle", true] }, { $eq: [ "$status", "INACTIVE" ] } ] },
then: -1 }
]
}
}
}
}
},
{
$project:{
_id: 0,
iid: "$_id.iid",
pid: "$_id.pid",
count: 1
}
}
] )
[编辑添加 3]
注意:
分面查询在同一组文档上运行两个分面(TRUE 和 FALSE);这就像两个并行查询 运行。但是,存在一些代码重复以及用于在管道中调整文档以获得所需输出的额外阶段。
第二个查询避免了代码重复,聚合管道中的阶段要少得多。当输入数据集有大量文档要处理时,这将在性能方面有所不同。一般来说,较少的阶段意味着较少的文档迭代(因为一个阶段必须扫描前一阶段输出的文档)。