mirror of https://github.com/mongodb/mongo
78 KiB
78 KiB
1. Basic example with two joins
No join opt
Pipeline
[
{
"$lookup" : {
"from" : "basic_joins_md_foreign1",
"as" : "x",
"localField" : "a",
"foreignField" : "a"
}
},
{
"$unwind" : "$x"
},
{
"$lookup" : {
"from" : "basic_joins_md_foreign2",
"as" : "y",
"localField" : "b",
"foreignField" : "b"
}
},
{
"$unwind" : "$y"
}
]
Results
{ "_id" : 1, "a" : 1, "b" : "bar", "x" : { "_id" : 0, "a" : 1, "c" : "zoo", "d" : 1 }, "y" : { "_id" : 0, "b" : "bar", "d" : 2 } }
{ "_id" : 1, "a" : 1, "b" : "bar", "x" : { "_id" : 0, "a" : 1, "c" : "zoo", "d" : 1 }, "y" : { "_id" : 1, "b" : "bar", "d" : 6 } }
{ "_id" : 2, "a" : 2, "b" : "bar", "x" : { "_id" : 1, "a" : 2, "c" : "blah", "d" : 2 }, "y" : { "_id" : 0, "b" : "bar", "d" : 2 } }
{ "_id" : 2, "a" : 2, "b" : "bar", "x" : { "_id" : 1, "a" : 2, "c" : "blah", "d" : 2 }, "y" : { "_id" : 1, "b" : "bar", "d" : 6 } }
{ "_id" : 2, "a" : 2, "b" : "bar", "x" : { "_id" : 2, "a" : 2, "c" : "x", "d" : 3 }, "y" : { "_id" : 0, "b" : "bar", "d" : 2 } }
{ "_id" : 2, "a" : 2, "b" : "bar", "x" : { "_id" : 2, "a" : 2, "c" : "x", "d" : 3 }, "y" : { "_id" : 1, "b" : "bar", "d" : 6 } }
Summarized explain
Execution Engine: sbe
{
"queryShapeHash" : "2312073BEBB7A5E1754E2D03D9CB40B75C126DBF60867D4639E7E281C9E3DFAC",
"rejectedPlans" : [ ],
"winningPlan" : {
"asField" : "y",
"foreignCollection" : "test.basic_joins_md_foreign2",
"foreignField" : "b",
"inputStage" : {
"asField" : "x",
"foreignCollection" : "test.basic_joins_md_foreign1",
"foreignField" : "a",
"inputStage" : {
"direction" : "forward",
"filter" : {
},
"nss" : "test.basic_joins_md",
"stage" : "COLLSCAN"
},
"localField" : "a",
"scanDirection" : "forward",
"stage" : "EQ_LOOKUP_UNWIND",
"strategy" : "HashJoin"
},
"localField" : "b",
"planNodeId" : 3,
"scanDirection" : "forward",
"stage" : "EQ_LOOKUP_UNWIND",
"strategy" : "HashJoin"
}
}
With bottom-up plan enumeration (left-deep)
usedJoinOptimization: true
HASH_JOIN_EMBEDDING [b = b]
leftEmbeddingField: "none"
rightEmbeddingField: "y"
| |
| COLLSCAN [test.basic_joins_md_foreign2]
| direction: "forward"
|
HASH_JOIN_EMBEDDING [a = a]
leftEmbeddingField: "none"
rightEmbeddingField: "x"
| |
| COLLSCAN [test.basic_joins_md_foreign1]
| direction: "forward"
|
COLLSCAN [test.basic_joins_md]
direction: "forward"
With bottom-up plan enumeration (right-deep)
usedJoinOptimization: true
HASH_JOIN_EMBEDDING [b = b]
leftEmbeddingField: "y"
rightEmbeddingField: "none"
| |
| HASH_JOIN_EMBEDDING [a = a]
| leftEmbeddingField: "none"
| rightEmbeddingField: "x"
| | |
| | COLLSCAN [test.basic_joins_md_foreign1]
| | direction: "forward"
| |
| COLLSCAN [test.basic_joins_md]
| direction: "forward"
|
COLLSCAN [test.basic_joins_md_foreign2]
direction: "forward"
With bottom-up plan enumeration (zig-zag)
usedJoinOptimization: true
HASH_JOIN_EMBEDDING [b = b]
leftEmbeddingField: "none"
rightEmbeddingField: "y"
| |
| COLLSCAN [test.basic_joins_md_foreign2]
| direction: "forward"
|
HASH_JOIN_EMBEDDING [a = a]
leftEmbeddingField: "none"
rightEmbeddingField: "x"
| |
| COLLSCAN [test.basic_joins_md_foreign1]
| direction: "forward"
|
COLLSCAN [test.basic_joins_md]
direction: "forward"
With random order, seed 44, nested loop joins
usedJoinOptimization: true
NESTED_LOOP_JOIN_EMBEDDING [b = b]
leftEmbeddingField: "none"
rightEmbeddingField: "y"
| |
| COLLSCAN [test.basic_joins_md_foreign2]
| direction: "forward"
|
NESTED_LOOP_JOIN_EMBEDDING [a = a]
leftEmbeddingField: "x"
rightEmbeddingField: "none"
| |
| COLLSCAN [test.basic_joins_md]
| direction: "forward"
|
COLLSCAN [test.basic_joins_md_foreign1]
direction: "forward"
With random order, seed 44, hash join enabled
usedJoinOptimization: true
HASH_JOIN_EMBEDDING [b = b]
leftEmbeddingField: "none"
rightEmbeddingField: "y"
| |
| COLLSCAN [test.basic_joins_md_foreign2]
| direction: "forward"
|
HASH_JOIN_EMBEDDING [a = a]
leftEmbeddingField: "x"
rightEmbeddingField: "none"
| |
| COLLSCAN [test.basic_joins_md]
| direction: "forward"
|
COLLSCAN [test.basic_joins_md_foreign1]
direction: "forward"
With random order, seed 45, nested loop joins
usedJoinOptimization: true
HASH_JOIN_EMBEDDING [a = a]
leftEmbeddingField: "none"
rightEmbeddingField: "x"
| |
| COLLSCAN [test.basic_joins_md_foreign1]
| direction: "forward"
|
HASH_JOIN_EMBEDDING [b = b]
leftEmbeddingField: "y"
rightEmbeddingField: "none"
| |
| COLLSCAN [test.basic_joins_md]
| direction: "forward"
|
COLLSCAN [test.basic_joins_md_foreign2]
direction: "forward"
With random order, seed 45, hash join enabled
usedJoinOptimization: true
HASH_JOIN_EMBEDDING [a = a]
leftEmbeddingField: "none"
rightEmbeddingField: "x"
| |
| COLLSCAN [test.basic_joins_md_foreign1]
| direction: "forward"
|
HASH_JOIN_EMBEDDING [b = b]
leftEmbeddingField: "y"
rightEmbeddingField: "none"
| |
| COLLSCAN [test.basic_joins_md]
| direction: "forward"
|
COLLSCAN [test.basic_joins_md_foreign2]
direction: "forward"
With fixed order, index join
usedJoinOptimization: true
INDEXED_NESTED_LOOP_JOIN_EMBEDDING [a = a]
leftEmbeddingField: "none"
rightEmbeddingField: "x"
| |
| FETCH [test.basic_joins_md_foreign1]
|
| |
| INDEX_PROBE_NODE [test.basic_joins_md_foreign1]
| keyPattern: { "a" : 1 }
| indexName: "a_1"
| isMultiKey: false
| isUnique: false
| isSparse: false
| isPartial: false
|
NESTED_LOOP_JOIN_EMBEDDING [b = b]
leftEmbeddingField: "y"
rightEmbeddingField: "none"
| |
| COLLSCAN [test.basic_joins_md]
| direction: "forward"
|
COLLSCAN [test.basic_joins_md_foreign2]
direction: "forward"
With bottom-up plan enumeration and indexes
usedJoinOptimization: true
INDEXED_NESTED_LOOP_JOIN_EMBEDDING [b = b]
leftEmbeddingField: "none"
rightEmbeddingField: "y"
| |
| FETCH [test.basic_joins_md_foreign2]
|
| |
| INDEX_PROBE_NODE [test.basic_joins_md_foreign2]
| keyPattern: { "b" : 1 }
| indexName: "b_1"
| isMultiKey: false
| isUnique: false
| isSparse: false
| isPartial: false
|
INDEXED_NESTED_LOOP_JOIN_EMBEDDING [a = a]
leftEmbeddingField: "none"
rightEmbeddingField: "x"
| |
| FETCH [test.basic_joins_md_foreign1]
|
| |
| INDEX_PROBE_NODE [test.basic_joins_md_foreign1]
| keyPattern: { "a" : 1 }
| indexName: "a_1"
| isMultiKey: false
| isUnique: false
| isSparse: false
| isPartial: false
|
COLLSCAN [test.basic_joins_md]
direction: "forward"
2. Basic example with two joins and suffix
No join opt
Pipeline
[
{
"$lookup" : {
"from" : "basic_joins_md_foreign1",
"as" : "x",
"localField" : "a",
"foreignField" : "a"
}
},
{
"$unwind" : "$x"
},
{
"$lookup" : {
"from" : "basic_joins_md_foreign2",
"as" : "y",
"localField" : "b",
"foreignField" : "b"
}
},
{
"$unwind" : "$y"
},
{
"$sortByCount" : "$y.b"
}
]
Results
{ "_id" : "bar", "count" : 6 }
Summarized explain
Execution Engine: sbe
{
"queryShapeHash" : "8E0DF14D3DA69D8B1CF0361E869369F9C5E5F2F2A5D81998E6800BDA4F997B57",
"rejectedPlans" : [ ],
"winningPlan" : {
"inputStage" : {
"inputStage" : {
"asField" : "y",
"foreignCollection" : "test.basic_joins_md_foreign2",
"foreignField" : "b",
"inputStage" : {
"asField" : "x",
"foreignCollection" : "test.basic_joins_md_foreign1",
"foreignField" : "a",
"inputStage" : {
"inputStage" : {
"direction" : "forward",
"filter" : {
},
"nss" : "test.basic_joins_md",
"stage" : "COLLSCAN"
},
"stage" : "PROJECTION_SIMPLE",
"transformBy" : {
"_id" : false,
"a" : true,
"b" : true
}
},
"localField" : "a",
"scanDirection" : "forward",
"stage" : "EQ_LOOKUP_UNWIND",
"strategy" : "HashJoin"
},
"localField" : "b",
"scanDirection" : "forward",
"stage" : "EQ_LOOKUP_UNWIND",
"strategy" : "HashJoin"
},
"stage" : "GROUP"
},
"memLimit" : 104857600,
"planNodeId" : 6,
"sortPattern" : {
"count" : -1
},
"stage" : "SORT",
"type" : "default"
}
}
With bottom-up plan enumeration (left-deep)
usedJoinOptimization: true
HASH_JOIN_EMBEDDING [b = b]
leftEmbeddingField: "none"
rightEmbeddingField: "y"
| |
| COLLSCAN [test.basic_joins_md_foreign2]
| direction: "forward"
|
HASH_JOIN_EMBEDDING [a = a]
leftEmbeddingField: "none"
rightEmbeddingField: "x"
| |
| COLLSCAN [test.basic_joins_md_foreign1]
| direction: "forward"
|
PROJECTION_SIMPLE
transformBy: { "a" : true, "b" : true, "_id" : false }
|
COLLSCAN [test.basic_joins_md]
direction: "forward"
With bottom-up plan enumeration (right-deep)
usedJoinOptimization: true
HASH_JOIN_EMBEDDING [b = b]
leftEmbeddingField: "y"
rightEmbeddingField: "none"
| |
| HASH_JOIN_EMBEDDING [a = a]
| leftEmbeddingField: "none"
| rightEmbeddingField: "x"
| | |
| | COLLSCAN [test.basic_joins_md_foreign1]
| | direction: "forward"
| |
| PROJECTION_SIMPLE
| transformBy: { "a" : true, "b" : true, "_id" : false }
| |
| COLLSCAN [test.basic_joins_md]
| direction: "forward"
|
COLLSCAN [test.basic_joins_md_foreign2]
direction: "forward"
With bottom-up plan enumeration (zig-zag)
usedJoinOptimization: true
HASH_JOIN_EMBEDDING [b = b]
leftEmbeddingField: "none"
rightEmbeddingField: "y"
| |
| COLLSCAN [test.basic_joins_md_foreign2]
| direction: "forward"
|
HASH_JOIN_EMBEDDING [a = a]
leftEmbeddingField: "none"
rightEmbeddingField: "x"
| |
| COLLSCAN [test.basic_joins_md_foreign1]
| direction: "forward"
|
PROJECTION_SIMPLE
transformBy: { "a" : true, "b" : true, "_id" : false }
|
COLLSCAN [test.basic_joins_md]
direction: "forward"
With random order, seed 44, nested loop joins
usedJoinOptimization: true
NESTED_LOOP_JOIN_EMBEDDING [b = b]
leftEmbeddingField: "none"
rightEmbeddingField: "y"
| |
| COLLSCAN [test.basic_joins_md_foreign2]
| direction: "forward"
|
NESTED_LOOP_JOIN_EMBEDDING [a = a]
leftEmbeddingField: "x"
rightEmbeddingField: "none"
| |
| PROJECTION_SIMPLE
| transformBy: { "a" : true, "b" : true, "_id" : false }
| |
| COLLSCAN [test.basic_joins_md]
| direction: "forward"
|
COLLSCAN [test.basic_joins_md_foreign1]
direction: "forward"
With random order, seed 44, hash join enabled
usedJoinOptimization: true
HASH_JOIN_EMBEDDING [b = b]
leftEmbeddingField: "none"
rightEmbeddingField: "y"
| |
| COLLSCAN [test.basic_joins_md_foreign2]
| direction: "forward"
|
HASH_JOIN_EMBEDDING [a = a]
leftEmbeddingField: "x"
rightEmbeddingField: "none"
| |
| PROJECTION_SIMPLE
| transformBy: { "a" : true, "b" : true, "_id" : false }
| |
| COLLSCAN [test.basic_joins_md]
| direction: "forward"
|
COLLSCAN [test.basic_joins_md_foreign1]
direction: "forward"
With random order, seed 45, nested loop joins
usedJoinOptimization: true
HASH_JOIN_EMBEDDING [a = a]
leftEmbeddingField: "none"
rightEmbeddingField: "x"
| |
| COLLSCAN [test.basic_joins_md_foreign1]
| direction: "forward"
|
HASH_JOIN_EMBEDDING [b = b]
leftEmbeddingField: "y"
rightEmbeddingField: "none"
| |
| PROJECTION_SIMPLE
| transformBy: { "a" : true, "b" : true, "_id" : false }
| |
| COLLSCAN [test.basic_joins_md]
| direction: "forward"
|
COLLSCAN [test.basic_joins_md_foreign2]
direction: "forward"
With random order, seed 45, hash join enabled
usedJoinOptimization: true
HASH_JOIN_EMBEDDING [a = a]
leftEmbeddingField: "none"
rightEmbeddingField: "x"
| |
| COLLSCAN [test.basic_joins_md_foreign1]
| direction: "forward"
|
HASH_JOIN_EMBEDDING [b = b]
leftEmbeddingField: "y"
rightEmbeddingField: "none"
| |
| PROJECTION_SIMPLE
| transformBy: { "a" : true, "b" : true, "_id" : false }
| |
| COLLSCAN [test.basic_joins_md]
| direction: "forward"
|
COLLSCAN [test.basic_joins_md_foreign2]
direction: "forward"
With fixed order, index join
usedJoinOptimization: true
INDEXED_NESTED_LOOP_JOIN_EMBEDDING [a = a]
leftEmbeddingField: "none"
rightEmbeddingField: "x"
| |
| FETCH [test.basic_joins_md_foreign1]
|
| |
| INDEX_PROBE_NODE [test.basic_joins_md_foreign1]
| keyPattern: { "a" : 1 }
| indexName: "a_1"
| isMultiKey: false
| isUnique: false
| isSparse: false
| isPartial: false
|
NESTED_LOOP_JOIN_EMBEDDING [b = b]
leftEmbeddingField: "y"
rightEmbeddingField: "none"
| |
| PROJECTION_SIMPLE
| transformBy: { "a" : true, "b" : true, "_id" : false }
| |
| COLLSCAN [test.basic_joins_md]
| direction: "forward"
|
COLLSCAN [test.basic_joins_md_foreign2]
direction: "forward"
With bottom-up plan enumeration and indexes
usedJoinOptimization: true
INDEXED_NESTED_LOOP_JOIN_EMBEDDING [b = b]
leftEmbeddingField: "none"
rightEmbeddingField: "y"
| |
| FETCH [test.basic_joins_md_foreign2]
|
| |
| INDEX_PROBE_NODE [test.basic_joins_md_foreign2]
| keyPattern: { "b" : 1 }
| indexName: "b_1"
| isMultiKey: false
| isUnique: false
| isSparse: false
| isPartial: false
|
INDEXED_NESTED_LOOP_JOIN_EMBEDDING [a = a]
leftEmbeddingField: "none"
rightEmbeddingField: "x"
| |
| FETCH [test.basic_joins_md_foreign1]
|
| |
| INDEX_PROBE_NODE [test.basic_joins_md_foreign1]
| keyPattern: { "a" : 1 }
| indexName: "a_1"
| isMultiKey: false
| isUnique: false
| isSparse: false
| isPartial: false
|
PROJECTION_SIMPLE
transformBy: { "a" : true, "b" : true, "_id" : false }
|
COLLSCAN [test.basic_joins_md]
direction: "forward"
3. Example with two joins, suffix, and sub-pipeline with un-correlated $match
No join opt
Pipeline
[
{
"$lookup" : {
"from" : "basic_joins_md_foreign1",
"as" : "x",
"localField" : "a",
"foreignField" : "a",
"pipeline" : [
{
"$match" : {
"d" : {
"$lt" : 3
}
}
}
]
}
},
{
"$unwind" : "$x"
},
{
"$lookup" : {
"from" : "basic_joins_md_foreign2",
"as" : "y",
"localField" : "b",
"foreignField" : "b",
"pipeline" : [
{
"$match" : {
"b" : {
"$gt" : "aaa"
}
}
}
]
}
},
{
"$unwind" : "$y"
},
{
"$sortByCount" : "$x.a"
}
]
Results
{ "_id" : 1, "count" : 2 }
{ "_id" : 2, "count" : 2 }
Summarized explain
Execution Engine: sbe
{
"queryShapeHash" : "39062D46AC66A096B98DB7B9AD3C198F432183DF3436553F59C3EC8B5252F1EA",
"stages" : [
{
"$cursor" : {
"rejectedPlans" : [ ],
"winningPlan" : {
"inputStage" : {
"direction" : "forward",
"filter" : {
},
"nss" : "test.basic_joins_md",
"stage" : "COLLSCAN"
},
"planNodeId" : 2,
"stage" : "PROJECTION_SIMPLE",
"transformBy" : {
"_id" : false,
"a" : true,
"b" : true
}
}
}
},
{
"$lookup" : {
"as" : "x",
"foreignField" : "a",
"from" : "basic_joins_md_foreign1",
"let" : {
},
"localField" : "a",
"pipeline" : [
{
"$match" : {
"d" : {
"$lt" : 3
}
}
}
],
"unwinding" : {
"preserveNullAndEmptyArrays" : false
}
}
},
{
"$lookup" : {
"as" : "y",
"foreignField" : "b",
"from" : "basic_joins_md_foreign2",
"let" : {
},
"localField" : "b",
"pipeline" : [
{
"$match" : {
"b" : {
"$gt" : "aaa"
}
}
}
],
"unwinding" : {
"preserveNullAndEmptyArrays" : false
}
}
},
{
"$group" : {
"$willBeMerged" : false,
"_id" : "$x.a",
"count" : {
"$sum" : {
"$const" : 1
}
}
}
},
{
"$sort" : {
"sortKey" : {
"count" : -1
}
}
}
]
}
With bottom-up plan enumeration (left-deep)
usedJoinOptimization: true
HASH_JOIN_EMBEDDING [b = b]
leftEmbeddingField: "none"
rightEmbeddingField: "y"
| |
| COLLSCAN [test.basic_joins_md_foreign2]
| filter: { "b" : { "$gt" : "aaa" } }
| direction: "forward"
|
HASH_JOIN_EMBEDDING [a = a]
leftEmbeddingField: "none"
rightEmbeddingField: "x"
| |
| COLLSCAN [test.basic_joins_md_foreign1]
| filter: { "d" : { "$lt" : 3 } }
| direction: "forward"
|
PROJECTION_SIMPLE
transformBy: { "a" : true, "b" : true, "_id" : false }
|
COLLSCAN [test.basic_joins_md]
direction: "forward"
With bottom-up plan enumeration (right-deep)
usedJoinOptimization: true
HASH_JOIN_EMBEDDING [b = b]
leftEmbeddingField: "y"
rightEmbeddingField: "none"
| |
| HASH_JOIN_EMBEDDING [a = a]
| leftEmbeddingField: "none"
| rightEmbeddingField: "x"
| | |
| | COLLSCAN [test.basic_joins_md_foreign1]
| | filter: { "d" : { "$lt" : 3 } }
| | direction: "forward"
| |
| PROJECTION_SIMPLE
| transformBy: { "a" : true, "b" : true, "_id" : false }
| |
| COLLSCAN [test.basic_joins_md]
| direction: "forward"
|
COLLSCAN [test.basic_joins_md_foreign2]
filter: { "b" : { "$gt" : "aaa" } }
direction: "forward"
With bottom-up plan enumeration (zig-zag)
usedJoinOptimization: true
HASH_JOIN_EMBEDDING [b = b]
leftEmbeddingField: "none"
rightEmbeddingField: "y"
| |
| COLLSCAN [test.basic_joins_md_foreign2]
| filter: { "b" : { "$gt" : "aaa" } }
| direction: "forward"
|
HASH_JOIN_EMBEDDING [a = a]
leftEmbeddingField: "none"
rightEmbeddingField: "x"
| |
| COLLSCAN [test.basic_joins_md_foreign1]
| filter: { "d" : { "$lt" : 3 } }
| direction: "forward"
|
PROJECTION_SIMPLE
transformBy: { "a" : true, "b" : true, "_id" : false }
|
COLLSCAN [test.basic_joins_md]
direction: "forward"
With random order, seed 44, nested loop joins
usedJoinOptimization: true
NESTED_LOOP_JOIN_EMBEDDING [b = b]
leftEmbeddingField: "none"
rightEmbeddingField: "y"
| |
| COLLSCAN [test.basic_joins_md_foreign2]
| filter: { "b" : { "$gt" : "aaa" } }
| direction: "forward"
|
NESTED_LOOP_JOIN_EMBEDDING [a = a]
leftEmbeddingField: "x"
rightEmbeddingField: "none"
| |
| PROJECTION_SIMPLE
| transformBy: { "a" : true, "b" : true, "_id" : false }
| |
| COLLSCAN [test.basic_joins_md]
| direction: "forward"
|
COLLSCAN [test.basic_joins_md_foreign1]
filter: { "d" : { "$lt" : 3 } }
direction: "forward"
With random order, seed 44, hash join enabled
usedJoinOptimization: true
HASH_JOIN_EMBEDDING [b = b]
leftEmbeddingField: "none"
rightEmbeddingField: "y"
| |
| COLLSCAN [test.basic_joins_md_foreign2]
| filter: { "b" : { "$gt" : "aaa" } }
| direction: "forward"
|
HASH_JOIN_EMBEDDING [a = a]
leftEmbeddingField: "x"
rightEmbeddingField: "none"
| |
| PROJECTION_SIMPLE
| transformBy: { "a" : true, "b" : true, "_id" : false }
| |
| COLLSCAN [test.basic_joins_md]
| direction: "forward"
|
COLLSCAN [test.basic_joins_md_foreign1]
filter: { "d" : { "$lt" : 3 } }
direction: "forward"
With random order, seed 45, nested loop joins
usedJoinOptimization: true
HASH_JOIN_EMBEDDING [a = a]
leftEmbeddingField: "none"
rightEmbeddingField: "x"
| |
| COLLSCAN [test.basic_joins_md_foreign1]
| filter: { "d" : { "$lt" : 3 } }
| direction: "forward"
|
HASH_JOIN_EMBEDDING [b = b]
leftEmbeddingField: "y"
rightEmbeddingField: "none"
| |
| PROJECTION_SIMPLE
| transformBy: { "a" : true, "b" : true, "_id" : false }
| |
| COLLSCAN [test.basic_joins_md]
| direction: "forward"
|
COLLSCAN [test.basic_joins_md_foreign2]
filter: { "b" : { "$gt" : "aaa" } }
direction: "forward"
With random order, seed 45, hash join enabled
usedJoinOptimization: true
HASH_JOIN_EMBEDDING [a = a]
leftEmbeddingField: "none"
rightEmbeddingField: "x"
| |
| COLLSCAN [test.basic_joins_md_foreign1]
| filter: { "d" : { "$lt" : 3 } }
| direction: "forward"
|
HASH_JOIN_EMBEDDING [b = b]
leftEmbeddingField: "y"
rightEmbeddingField: "none"
| |
| PROJECTION_SIMPLE
| transformBy: { "a" : true, "b" : true, "_id" : false }
| |
| COLLSCAN [test.basic_joins_md]
| direction: "forward"
|
COLLSCAN [test.basic_joins_md_foreign2]
filter: { "b" : { "$gt" : "aaa" } }
direction: "forward"
With fixed order, index join
usedJoinOptimization: true
INDEXED_NESTED_LOOP_JOIN_EMBEDDING [a = a]
leftEmbeddingField: "none"
rightEmbeddingField: "x"
| |
| FETCH [test.basic_joins_md_foreign1]
| filter: { "d" : { "$lt" : 3 } }
| |
| INDEX_PROBE_NODE [test.basic_joins_md_foreign1]
| keyPattern: { "a" : 1 }
| indexName: "a_1"
| isMultiKey: false
| isUnique: false
| isSparse: false
| isPartial: false
|
NESTED_LOOP_JOIN_EMBEDDING [b = b]
leftEmbeddingField: "y"
rightEmbeddingField: "none"
| |
| PROJECTION_SIMPLE
| transformBy: { "a" : true, "b" : true, "_id" : false }
| |
| COLLSCAN [test.basic_joins_md]
| direction: "forward"
|
FETCH [test.basic_joins_md_foreign2]
|
IXSCAN [test.basic_joins_md_foreign2]
keyPattern: { "b" : 1 }
indexName: "b_1"
isMultiKey: false
multiKeyPaths: { "b" : [ ] }
isUnique: false
isSparse: false
isPartial: false
direction: "forward"
indexBounds: { "b" : [ "(\"aaa\", {})" ] }
With bottom-up plan enumeration and indexes
usedJoinOptimization: true
INDEXED_NESTED_LOOP_JOIN_EMBEDDING [b = b]
leftEmbeddingField: "none"
rightEmbeddingField: "y"
| |
| FETCH [test.basic_joins_md_foreign2]
| filter: { "b" : { "$gt" : "aaa" } }
| |
| INDEX_PROBE_NODE [test.basic_joins_md_foreign2]
| keyPattern: { "b" : 1 }
| indexName: "b_1"
| isMultiKey: false
| isUnique: false
| isSparse: false
| isPartial: false
|
INDEXED_NESTED_LOOP_JOIN_EMBEDDING [a = a]
leftEmbeddingField: "none"
rightEmbeddingField: "x"
| |
| FETCH [test.basic_joins_md_foreign1]
| filter: { "d" : { "$lt" : 3 } }
| |
| INDEX_PROBE_NODE [test.basic_joins_md_foreign1]
| keyPattern: { "a" : 1 }
| indexName: "a_1"
| isMultiKey: false
| isUnique: false
| isSparse: false
| isPartial: false
|
PROJECTION_SIMPLE
transformBy: { "a" : true, "b" : true, "_id" : false }
|
COLLSCAN [test.basic_joins_md]
direction: "forward"
4. Example with two joins and sub-pipeline with un-correlated $match
No join opt
Pipeline
[
{
"$lookup" : {
"from" : "basic_joins_md_foreign1",
"as" : "x",
"localField" : "a",
"foreignField" : "a",
"pipeline" : [
{
"$match" : {
"d" : {
"$lt" : 3
}
}
}
]
}
},
{
"$unwind" : "$x"
},
{
"$lookup" : {
"from" : "basic_joins_md_foreign2",
"as" : "y",
"localField" : "b",
"foreignField" : "b",
"pipeline" : [
{
"$match" : {
"b" : {
"$gt" : "aaa"
}
}
}
]
}
},
{
"$unwind" : "$y"
}
]
Results
{ "_id" : 1, "a" : 1, "b" : "bar", "x" : { "_id" : 0, "a" : 1, "c" : "zoo", "d" : 1 }, "y" : { "_id" : 0, "b" : "bar", "d" : 2 } }
{ "_id" : 1, "a" : 1, "b" : "bar", "x" : { "_id" : 0, "a" : 1, "c" : "zoo", "d" : 1 }, "y" : { "_id" : 1, "b" : "bar", "d" : 6 } }
{ "_id" : 2, "a" : 2, "b" : "bar", "x" : { "_id" : 1, "a" : 2, "c" : "blah", "d" : 2 }, "y" : { "_id" : 0, "b" : "bar", "d" : 2 } }
{ "_id" : 2, "a" : 2, "b" : "bar", "x" : { "_id" : 1, "a" : 2, "c" : "blah", "d" : 2 }, "y" : { "_id" : 1, "b" : "bar", "d" : 6 } }
Summarized explain
Execution Engine: sbe
{
"queryShapeHash" : "6E1AD01BB023E5575DBF8997EA4E7E46A5BCCAA49D659AFD0AB18E0D1E797FF4",
"stages" : [
{
"$cursor" : {
"rejectedPlans" : [ ],
"winningPlan" : {
"direction" : "forward",
"filter" : {
},
"nss" : "test.basic_joins_md",
"planNodeId" : 1,
"stage" : "COLLSCAN"
}
}
},
{
"$lookup" : {
"as" : "x",
"foreignField" : "a",
"from" : "basic_joins_md_foreign1",
"let" : {
},
"localField" : "a",
"pipeline" : [
{
"$match" : {
"d" : {
"$lt" : 3
}
}
}
],
"unwinding" : {
"preserveNullAndEmptyArrays" : false
}
}
},
{
"$lookup" : {
"as" : "y",
"foreignField" : "b",
"from" : "basic_joins_md_foreign2",
"let" : {
},
"localField" : "b",
"pipeline" : [
{
"$match" : {
"b" : {
"$gt" : "aaa"
}
}
}
],
"unwinding" : {
"preserveNullAndEmptyArrays" : false
}
}
}
]
}
With bottom-up plan enumeration (left-deep)
usedJoinOptimization: true
HASH_JOIN_EMBEDDING [b = b]
leftEmbeddingField: "none"
rightEmbeddingField: "y"
| |
| COLLSCAN [test.basic_joins_md_foreign2]
| filter: { "b" : { "$gt" : "aaa" } }
| direction: "forward"
|
HASH_JOIN_EMBEDDING [a = a]
leftEmbeddingField: "none"
rightEmbeddingField: "x"
| |
| COLLSCAN [test.basic_joins_md_foreign1]
| filter: { "d" : { "$lt" : 3 } }
| direction: "forward"
|
COLLSCAN [test.basic_joins_md]
direction: "forward"
With bottom-up plan enumeration (right-deep)
usedJoinOptimization: true
HASH_JOIN_EMBEDDING [b = b]
leftEmbeddingField: "y"
rightEmbeddingField: "none"
| |
| HASH_JOIN_EMBEDDING [a = a]
| leftEmbeddingField: "none"
| rightEmbeddingField: "x"
| | |
| | COLLSCAN [test.basic_joins_md_foreign1]
| | filter: { "d" : { "$lt" : 3 } }
| | direction: "forward"
| |
| COLLSCAN [test.basic_joins_md]
| direction: "forward"
|
COLLSCAN [test.basic_joins_md_foreign2]
filter: { "b" : { "$gt" : "aaa" } }
direction: "forward"
With bottom-up plan enumeration (zig-zag)
usedJoinOptimization: true
HASH_JOIN_EMBEDDING [b = b]
leftEmbeddingField: "none"
rightEmbeddingField: "y"
| |
| COLLSCAN [test.basic_joins_md_foreign2]
| filter: { "b" : { "$gt" : "aaa" } }
| direction: "forward"
|
HASH_JOIN_EMBEDDING [a = a]
leftEmbeddingField: "none"
rightEmbeddingField: "x"
| |
| COLLSCAN [test.basic_joins_md_foreign1]
| filter: { "d" : { "$lt" : 3 } }
| direction: "forward"
|
COLLSCAN [test.basic_joins_md]
direction: "forward"
With random order, seed 44, nested loop joins
usedJoinOptimization: true
NESTED_LOOP_JOIN_EMBEDDING [b = b]
leftEmbeddingField: "none"
rightEmbeddingField: "y"
| |
| COLLSCAN [test.basic_joins_md_foreign2]
| filter: { "b" : { "$gt" : "aaa" } }
| direction: "forward"
|
NESTED_LOOP_JOIN_EMBEDDING [a = a]
leftEmbeddingField: "x"
rightEmbeddingField: "none"
| |
| COLLSCAN [test.basic_joins_md]
| direction: "forward"
|
COLLSCAN [test.basic_joins_md_foreign1]
filter: { "d" : { "$lt" : 3 } }
direction: "forward"
With random order, seed 44, hash join enabled
usedJoinOptimization: true
HASH_JOIN_EMBEDDING [b = b]
leftEmbeddingField: "none"
rightEmbeddingField: "y"
| |
| COLLSCAN [test.basic_joins_md_foreign2]
| filter: { "b" : { "$gt" : "aaa" } }
| direction: "forward"
|
HASH_JOIN_EMBEDDING [a = a]
leftEmbeddingField: "x"
rightEmbeddingField: "none"
| |
| COLLSCAN [test.basic_joins_md]
| direction: "forward"
|
COLLSCAN [test.basic_joins_md_foreign1]
filter: { "d" : { "$lt" : 3 } }
direction: "forward"
With random order, seed 45, nested loop joins
usedJoinOptimization: true
HASH_JOIN_EMBEDDING [a = a]
leftEmbeddingField: "none"
rightEmbeddingField: "x"
| |
| COLLSCAN [test.basic_joins_md_foreign1]
| filter: { "d" : { "$lt" : 3 } }
| direction: "forward"
|
HASH_JOIN_EMBEDDING [b = b]
leftEmbeddingField: "y"
rightEmbeddingField: "none"
| |
| COLLSCAN [test.basic_joins_md]
| direction: "forward"
|
COLLSCAN [test.basic_joins_md_foreign2]
filter: { "b" : { "$gt" : "aaa" } }
direction: "forward"
With random order, seed 45, hash join enabled
usedJoinOptimization: true
HASH_JOIN_EMBEDDING [a = a]
leftEmbeddingField: "none"
rightEmbeddingField: "x"
| |
| COLLSCAN [test.basic_joins_md_foreign1]
| filter: { "d" : { "$lt" : 3 } }
| direction: "forward"
|
HASH_JOIN_EMBEDDING [b = b]
leftEmbeddingField: "y"
rightEmbeddingField: "none"
| |
| COLLSCAN [test.basic_joins_md]
| direction: "forward"
|
COLLSCAN [test.basic_joins_md_foreign2]
filter: { "b" : { "$gt" : "aaa" } }
direction: "forward"
With fixed order, index join
usedJoinOptimization: true
INDEXED_NESTED_LOOP_JOIN_EMBEDDING [a = a]
leftEmbeddingField: "none"
rightEmbeddingField: "x"
| |
| FETCH [test.basic_joins_md_foreign1]
| filter: { "d" : { "$lt" : 3 } }
| |
| INDEX_PROBE_NODE [test.basic_joins_md_foreign1]
| keyPattern: { "a" : 1 }
| indexName: "a_1"
| isMultiKey: false
| isUnique: false
| isSparse: false
| isPartial: false
|
NESTED_LOOP_JOIN_EMBEDDING [b = b]
leftEmbeddingField: "y"
rightEmbeddingField: "none"
| |
| COLLSCAN [test.basic_joins_md]
| direction: "forward"
|
FETCH [test.basic_joins_md_foreign2]
|
IXSCAN [test.basic_joins_md_foreign2]
keyPattern: { "b" : 1 }
indexName: "b_1"
isMultiKey: false
multiKeyPaths: { "b" : [ ] }
isUnique: false
isSparse: false
isPartial: false
direction: "forward"
indexBounds: { "b" : [ "(\"aaa\", {})" ] }
With bottom-up plan enumeration and indexes
usedJoinOptimization: true
INDEXED_NESTED_LOOP_JOIN_EMBEDDING [b = b]
leftEmbeddingField: "none"
rightEmbeddingField: "y"
| |
| FETCH [test.basic_joins_md_foreign2]
| filter: { "b" : { "$gt" : "aaa" } }
| |
| INDEX_PROBE_NODE [test.basic_joins_md_foreign2]
| keyPattern: { "b" : 1 }
| indexName: "b_1"
| isMultiKey: false
| isUnique: false
| isSparse: false
| isPartial: false
|
INDEXED_NESTED_LOOP_JOIN_EMBEDDING [a = a]
leftEmbeddingField: "none"
rightEmbeddingField: "x"
| |
| FETCH [test.basic_joins_md_foreign1]
| filter: { "d" : { "$lt" : 3 } }
| |
| INDEX_PROBE_NODE [test.basic_joins_md_foreign1]
| keyPattern: { "a" : 1 }
| indexName: "a_1"
| isMultiKey: false
| isUnique: false
| isSparse: false
| isPartial: false
|
COLLSCAN [test.basic_joins_md]
direction: "forward"
5. Example with two joins, suffix, and sub-pipeline with un-correlated $match and $match prefix
No join opt
Pipeline
[
{
"$match" : {
"a" : {
"$gt" : 1
}
}
},
{
"$lookup" : {
"from" : "basic_joins_md_foreign1",
"as" : "x",
"localField" : "a",
"foreignField" : "a",
"pipeline" : [
{
"$match" : {
"d" : {
"$lt" : 3
}
}
}
]
}
},
{
"$unwind" : "$x"
},
{
"$lookup" : {
"from" : "basic_joins_md_foreign2",
"as" : "y",
"localField" : "b",
"foreignField" : "b",
"pipeline" : [
{
"$match" : {
"b" : {
"$gt" : "aaa"
}
}
}
]
}
},
{
"$unwind" : "$y"
},
{
"$sortByCount" : "$x.a"
}
]
Results
{ "_id" : 2, "count" : 2 }
Summarized explain
Execution Engine: sbe
{
"queryShapeHash" : "7D59BE511C0D33652DB26A61DFFA0D36F47580971FB97DF9C3C4BC3A3F52F932",
"stages" : [
{
"$cursor" : {
"rejectedPlans" : [ ],
"winningPlan" : {
"inputStage" : {
"direction" : "forward",
"filter" : {
"a" : {
"$gt" : 1
}
},
"nss" : "test.basic_joins_md",
"stage" : "COLLSCAN"
},
"planNodeId" : 2,
"stage" : "PROJECTION_SIMPLE",
"transformBy" : {
"_id" : false,
"a" : true,
"b" : true
}
}
}
},
{
"$lookup" : {
"as" : "x",
"foreignField" : "a",
"from" : "basic_joins_md_foreign1",
"let" : {
},
"localField" : "a",
"pipeline" : [
{
"$match" : {
"d" : {
"$lt" : 3
}
}
}
],
"unwinding" : {
"preserveNullAndEmptyArrays" : false
}
}
},
{
"$lookup" : {
"as" : "y",
"foreignField" : "b",
"from" : "basic_joins_md_foreign2",
"let" : {
},
"localField" : "b",
"pipeline" : [
{
"$match" : {
"b" : {
"$gt" : "aaa"
}
}
}
],
"unwinding" : {
"preserveNullAndEmptyArrays" : false
}
}
},
{
"$group" : {
"$willBeMerged" : false,
"_id" : "$x.a",
"count" : {
"$sum" : {
"$const" : 1
}
}
}
},
{
"$sort" : {
"sortKey" : {
"count" : -1
}
}
}
]
}
With bottom-up plan enumeration (left-deep)
usedJoinOptimization: true
HASH_JOIN_EMBEDDING [b = b]
leftEmbeddingField: "none"
rightEmbeddingField: "y"
| |
| COLLSCAN [test.basic_joins_md_foreign2]
| filter: { "b" : { "$gt" : "aaa" } }
| direction: "forward"
|
HASH_JOIN_EMBEDDING [a = a]
leftEmbeddingField: "none"
rightEmbeddingField: "x"
| |
| COLLSCAN [test.basic_joins_md_foreign1]
| filter: { "d" : { "$lt" : 3 } }
| direction: "forward"
|
PROJECTION_SIMPLE
transformBy: { "a" : true, "b" : true, "_id" : false }
|
COLLSCAN [test.basic_joins_md]
filter: { "a" : { "$gt" : 1 } }
direction: "forward"
With bottom-up plan enumeration (right-deep)
usedJoinOptimization: true
HASH_JOIN_EMBEDDING [b = b]
leftEmbeddingField: "y"
rightEmbeddingField: "none"
| |
| HASH_JOIN_EMBEDDING [a = a]
| leftEmbeddingField: "none"
| rightEmbeddingField: "x"
| | |
| | COLLSCAN [test.basic_joins_md_foreign1]
| | filter: { "d" : { "$lt" : 3 } }
| | direction: "forward"
| |
| PROJECTION_SIMPLE
| transformBy: { "a" : true, "b" : true, "_id" : false }
| |
| COLLSCAN [test.basic_joins_md]
| filter: { "a" : { "$gt" : 1 } }
| direction: "forward"
|
COLLSCAN [test.basic_joins_md_foreign2]
filter: { "b" : { "$gt" : "aaa" } }
direction: "forward"
With bottom-up plan enumeration (zig-zag)
usedJoinOptimization: true
HASH_JOIN_EMBEDDING [b = b]
leftEmbeddingField: "none"
rightEmbeddingField: "y"
| |
| COLLSCAN [test.basic_joins_md_foreign2]
| filter: { "b" : { "$gt" : "aaa" } }
| direction: "forward"
|
HASH_JOIN_EMBEDDING [a = a]
leftEmbeddingField: "none"
rightEmbeddingField: "x"
| |
| COLLSCAN [test.basic_joins_md_foreign1]
| filter: { "d" : { "$lt" : 3 } }
| direction: "forward"
|
PROJECTION_SIMPLE
transformBy: { "a" : true, "b" : true, "_id" : false }
|
COLLSCAN [test.basic_joins_md]
filter: { "a" : { "$gt" : 1 } }
direction: "forward"
With random order, seed 44, nested loop joins
usedJoinOptimization: true
NESTED_LOOP_JOIN_EMBEDDING [b = b]
leftEmbeddingField: "none"
rightEmbeddingField: "y"
| |
| COLLSCAN [test.basic_joins_md_foreign2]
| filter: { "b" : { "$gt" : "aaa" } }
| direction: "forward"
|
NESTED_LOOP_JOIN_EMBEDDING [a = a]
leftEmbeddingField: "x"
rightEmbeddingField: "none"
| |
| PROJECTION_SIMPLE
| transformBy: { "a" : true, "b" : true, "_id" : false }
| |
| COLLSCAN [test.basic_joins_md]
| filter: { "a" : { "$gt" : 1 } }
| direction: "forward"
|
COLLSCAN [test.basic_joins_md_foreign1]
filter: { "d" : { "$lt" : 3 } }
direction: "forward"
With random order, seed 44, hash join enabled
usedJoinOptimization: true
HASH_JOIN_EMBEDDING [b = b]
leftEmbeddingField: "none"
rightEmbeddingField: "y"
| |
| COLLSCAN [test.basic_joins_md_foreign2]
| filter: { "b" : { "$gt" : "aaa" } }
| direction: "forward"
|
HASH_JOIN_EMBEDDING [a = a]
leftEmbeddingField: "x"
rightEmbeddingField: "none"
| |
| PROJECTION_SIMPLE
| transformBy: { "a" : true, "b" : true, "_id" : false }
| |
| COLLSCAN [test.basic_joins_md]
| filter: { "a" : { "$gt" : 1 } }
| direction: "forward"
|
COLLSCAN [test.basic_joins_md_foreign1]
filter: { "d" : { "$lt" : 3 } }
direction: "forward"
With random order, seed 45, nested loop joins
usedJoinOptimization: true
HASH_JOIN_EMBEDDING [a = a]
leftEmbeddingField: "none"
rightEmbeddingField: "x"
| |
| COLLSCAN [test.basic_joins_md_foreign1]
| filter: { "d" : { "$lt" : 3 } }
| direction: "forward"
|
HASH_JOIN_EMBEDDING [b = b]
leftEmbeddingField: "y"
rightEmbeddingField: "none"
| |
| PROJECTION_SIMPLE
| transformBy: { "a" : true, "b" : true, "_id" : false }
| |
| COLLSCAN [test.basic_joins_md]
| filter: { "a" : { "$gt" : 1 } }
| direction: "forward"
|
COLLSCAN [test.basic_joins_md_foreign2]
filter: { "b" : { "$gt" : "aaa" } }
direction: "forward"
With random order, seed 45, hash join enabled
usedJoinOptimization: true
HASH_JOIN_EMBEDDING [a = a]
leftEmbeddingField: "none"
rightEmbeddingField: "x"
| |
| COLLSCAN [test.basic_joins_md_foreign1]
| filter: { "d" : { "$lt" : 3 } }
| direction: "forward"
|
HASH_JOIN_EMBEDDING [b = b]
leftEmbeddingField: "y"
rightEmbeddingField: "none"
| |
| PROJECTION_SIMPLE
| transformBy: { "a" : true, "b" : true, "_id" : false }
| |
| COLLSCAN [test.basic_joins_md]
| filter: { "a" : { "$gt" : 1 } }
| direction: "forward"
|
COLLSCAN [test.basic_joins_md_foreign2]
filter: { "b" : { "$gt" : "aaa" } }
direction: "forward"
With fixed order, index join
usedJoinOptimization: true
INDEXED_NESTED_LOOP_JOIN_EMBEDDING [a = a]
leftEmbeddingField: "none"
rightEmbeddingField: "x"
| |
| FETCH [test.basic_joins_md_foreign1]
| filter: { "d" : { "$lt" : 3 } }
| |
| INDEX_PROBE_NODE [test.basic_joins_md_foreign1]
| keyPattern: { "a" : 1 }
| indexName: "a_1"
| isMultiKey: false
| isUnique: false
| isSparse: false
| isPartial: false
|
NESTED_LOOP_JOIN_EMBEDDING [b = b]
leftEmbeddingField: "y"
rightEmbeddingField: "none"
| |
| PROJECTION_SIMPLE
| transformBy: { "a" : true, "b" : true, "_id" : false }
| |
| COLLSCAN [test.basic_joins_md]
| filter: { "a" : { "$gt" : 1 } }
| direction: "forward"
|
FETCH [test.basic_joins_md_foreign2]
|
IXSCAN [test.basic_joins_md_foreign2]
keyPattern: { "b" : 1 }
indexName: "b_1"
isMultiKey: false
multiKeyPaths: { "b" : [ ] }
isUnique: false
isSparse: false
isPartial: false
direction: "forward"
indexBounds: { "b" : [ "(\"aaa\", {})" ] }
With bottom-up plan enumeration and indexes
usedJoinOptimization: true
INDEXED_NESTED_LOOP_JOIN_EMBEDDING [b = b]
leftEmbeddingField: "none"
rightEmbeddingField: "y"
| |
| FETCH [test.basic_joins_md_foreign2]
| filter: { "b" : { "$gt" : "aaa" } }
| |
| INDEX_PROBE_NODE [test.basic_joins_md_foreign2]
| keyPattern: { "b" : 1 }
| indexName: "b_1"
| isMultiKey: false
| isUnique: false
| isSparse: false
| isPartial: false
|
INDEXED_NESTED_LOOP_JOIN_EMBEDDING [a = a]
leftEmbeddingField: "none"
rightEmbeddingField: "x"
| |
| FETCH [test.basic_joins_md_foreign1]
| filter: { "d" : { "$lt" : 3 } }
| |
| INDEX_PROBE_NODE [test.basic_joins_md_foreign1]
| keyPattern: { "a" : 1 }
| indexName: "a_1"
| isMultiKey: false
| isUnique: false
| isSparse: false
| isPartial: false
|
PROJECTION_SIMPLE
transformBy: { "a" : true, "b" : true, "_id" : false }
|
COLLSCAN [test.basic_joins_md]
filter: { "a" : { "$gt" : 1 } }
direction: "forward"
6. Example with two joins and sub-pipeline with un-correlated $match and $match prefix
No join opt
Pipeline
[
{
"$match" : {
"a" : {
"$gt" : 1
}
}
},
{
"$lookup" : {
"from" : "basic_joins_md_foreign1",
"as" : "x",
"localField" : "a",
"foreignField" : "a",
"pipeline" : [
{
"$match" : {
"d" : {
"$lt" : 3
}
}
}
]
}
},
{
"$unwind" : "$x"
},
{
"$lookup" : {
"from" : "basic_joins_md_foreign2",
"as" : "y",
"localField" : "b",
"foreignField" : "b",
"pipeline" : [
{
"$match" : {
"b" : {
"$gt" : "aaa"
}
}
}
]
}
},
{
"$unwind" : "$y"
}
]
Results
{ "_id" : 2, "a" : 2, "b" : "bar", "x" : { "_id" : 1, "a" : 2, "c" : "blah", "d" : 2 }, "y" : { "_id" : 0, "b" : "bar", "d" : 2 } }
{ "_id" : 2, "a" : 2, "b" : "bar", "x" : { "_id" : 1, "a" : 2, "c" : "blah", "d" : 2 }, "y" : { "_id" : 1, "b" : "bar", "d" : 6 } }
Summarized explain
Execution Engine: sbe
{
"queryShapeHash" : "D2D2550CF530351E25FFDB1BB9DBD96DD0CE98C0FA4082BADF1F9BC9F7579A03",
"stages" : [
{
"$cursor" : {
"rejectedPlans" : [ ],
"winningPlan" : {
"direction" : "forward",
"filter" : {
"a" : {
"$gt" : 1
}
},
"nss" : "test.basic_joins_md",
"planNodeId" : 1,
"stage" : "COLLSCAN"
}
}
},
{
"$lookup" : {
"as" : "x",
"foreignField" : "a",
"from" : "basic_joins_md_foreign1",
"let" : {
},
"localField" : "a",
"pipeline" : [
{
"$match" : {
"d" : {
"$lt" : 3
}
}
}
],
"unwinding" : {
"preserveNullAndEmptyArrays" : false
}
}
},
{
"$lookup" : {
"as" : "y",
"foreignField" : "b",
"from" : "basic_joins_md_foreign2",
"let" : {
},
"localField" : "b",
"pipeline" : [
{
"$match" : {
"b" : {
"$gt" : "aaa"
}
}
}
],
"unwinding" : {
"preserveNullAndEmptyArrays" : false
}
}
}
]
}
With bottom-up plan enumeration (left-deep)
usedJoinOptimization: true
HASH_JOIN_EMBEDDING [b = b]
leftEmbeddingField: "none"
rightEmbeddingField: "y"
| |
| COLLSCAN [test.basic_joins_md_foreign2]
| filter: { "b" : { "$gt" : "aaa" } }
| direction: "forward"
|
HASH_JOIN_EMBEDDING [a = a]
leftEmbeddingField: "none"
rightEmbeddingField: "x"
| |
| COLLSCAN [test.basic_joins_md_foreign1]
| filter: { "d" : { "$lt" : 3 } }
| direction: "forward"
|
COLLSCAN [test.basic_joins_md]
filter: { "a" : { "$gt" : 1 } }
direction: "forward"
With bottom-up plan enumeration (right-deep)
usedJoinOptimization: true
HASH_JOIN_EMBEDDING [b = b]
leftEmbeddingField: "y"
rightEmbeddingField: "none"
| |
| HASH_JOIN_EMBEDDING [a = a]
| leftEmbeddingField: "none"
| rightEmbeddingField: "x"
| | |
| | COLLSCAN [test.basic_joins_md_foreign1]
| | filter: { "d" : { "$lt" : 3 } }
| | direction: "forward"
| |
| COLLSCAN [test.basic_joins_md]
| filter: { "a" : { "$gt" : 1 } }
| direction: "forward"
|
COLLSCAN [test.basic_joins_md_foreign2]
filter: { "b" : { "$gt" : "aaa" } }
direction: "forward"
With bottom-up plan enumeration (zig-zag)
usedJoinOptimization: true
HASH_JOIN_EMBEDDING [b = b]
leftEmbeddingField: "none"
rightEmbeddingField: "y"
| |
| COLLSCAN [test.basic_joins_md_foreign2]
| filter: { "b" : { "$gt" : "aaa" } }
| direction: "forward"
|
HASH_JOIN_EMBEDDING [a = a]
leftEmbeddingField: "none"
rightEmbeddingField: "x"
| |
| COLLSCAN [test.basic_joins_md_foreign1]
| filter: { "d" : { "$lt" : 3 } }
| direction: "forward"
|
COLLSCAN [test.basic_joins_md]
filter: { "a" : { "$gt" : 1 } }
direction: "forward"
With random order, seed 44, nested loop joins
usedJoinOptimization: true
NESTED_LOOP_JOIN_EMBEDDING [b = b]
leftEmbeddingField: "none"
rightEmbeddingField: "y"
| |
| COLLSCAN [test.basic_joins_md_foreign2]
| filter: { "b" : { "$gt" : "aaa" } }
| direction: "forward"
|
NESTED_LOOP_JOIN_EMBEDDING [a = a]
leftEmbeddingField: "x"
rightEmbeddingField: "none"
| |
| COLLSCAN [test.basic_joins_md]
| filter: { "a" : { "$gt" : 1 } }
| direction: "forward"
|
COLLSCAN [test.basic_joins_md_foreign1]
filter: { "d" : { "$lt" : 3 } }
direction: "forward"
With random order, seed 44, hash join enabled
usedJoinOptimization: true
HASH_JOIN_EMBEDDING [b = b]
leftEmbeddingField: "none"
rightEmbeddingField: "y"
| |
| COLLSCAN [test.basic_joins_md_foreign2]
| filter: { "b" : { "$gt" : "aaa" } }
| direction: "forward"
|
HASH_JOIN_EMBEDDING [a = a]
leftEmbeddingField: "x"
rightEmbeddingField: "none"
| |
| COLLSCAN [test.basic_joins_md]
| filter: { "a" : { "$gt" : 1 } }
| direction: "forward"
|
COLLSCAN [test.basic_joins_md_foreign1]
filter: { "d" : { "$lt" : 3 } }
direction: "forward"
With random order, seed 45, nested loop joins
usedJoinOptimization: true
HASH_JOIN_EMBEDDING [a = a]
leftEmbeddingField: "none"
rightEmbeddingField: "x"
| |
| COLLSCAN [test.basic_joins_md_foreign1]
| filter: { "d" : { "$lt" : 3 } }
| direction: "forward"
|
HASH_JOIN_EMBEDDING [b = b]
leftEmbeddingField: "y"
rightEmbeddingField: "none"
| |
| COLLSCAN [test.basic_joins_md]
| filter: { "a" : { "$gt" : 1 } }
| direction: "forward"
|
COLLSCAN [test.basic_joins_md_foreign2]
filter: { "b" : { "$gt" : "aaa" } }
direction: "forward"
With random order, seed 45, hash join enabled
usedJoinOptimization: true
HASH_JOIN_EMBEDDING [a = a]
leftEmbeddingField: "none"
rightEmbeddingField: "x"
| |
| COLLSCAN [test.basic_joins_md_foreign1]
| filter: { "d" : { "$lt" : 3 } }
| direction: "forward"
|
HASH_JOIN_EMBEDDING [b = b]
leftEmbeddingField: "y"
rightEmbeddingField: "none"
| |
| COLLSCAN [test.basic_joins_md]
| filter: { "a" : { "$gt" : 1 } }
| direction: "forward"
|
COLLSCAN [test.basic_joins_md_foreign2]
filter: { "b" : { "$gt" : "aaa" } }
direction: "forward"
With fixed order, index join
usedJoinOptimization: true
INDEXED_NESTED_LOOP_JOIN_EMBEDDING [a = a]
leftEmbeddingField: "none"
rightEmbeddingField: "x"
| |
| FETCH [test.basic_joins_md_foreign1]
| filter: { "d" : { "$lt" : 3 } }
| |
| INDEX_PROBE_NODE [test.basic_joins_md_foreign1]
| keyPattern: { "a" : 1 }
| indexName: "a_1"
| isMultiKey: false
| isUnique: false
| isSparse: false
| isPartial: false
|
NESTED_LOOP_JOIN_EMBEDDING [b = b]
leftEmbeddingField: "y"
rightEmbeddingField: "none"
| |
| COLLSCAN [test.basic_joins_md]
| filter: { "a" : { "$gt" : 1 } }
| direction: "forward"
|
FETCH [test.basic_joins_md_foreign2]
|
IXSCAN [test.basic_joins_md_foreign2]
keyPattern: { "b" : 1 }
indexName: "b_1"
isMultiKey: false
multiKeyPaths: { "b" : [ ] }
isUnique: false
isSparse: false
isPartial: false
direction: "forward"
indexBounds: { "b" : [ "(\"aaa\", {})" ] }
With bottom-up plan enumeration and indexes
usedJoinOptimization: true
INDEXED_NESTED_LOOP_JOIN_EMBEDDING [b = b]
leftEmbeddingField: "none"
rightEmbeddingField: "y"
| |
| FETCH [test.basic_joins_md_foreign2]
| filter: { "b" : { "$gt" : "aaa" } }
| |
| INDEX_PROBE_NODE [test.basic_joins_md_foreign2]
| keyPattern: { "b" : 1 }
| indexName: "b_1"
| isMultiKey: false
| isUnique: false
| isSparse: false
| isPartial: false
|
INDEXED_NESTED_LOOP_JOIN_EMBEDDING [a = a]
leftEmbeddingField: "none"
rightEmbeddingField: "x"
| |
| FETCH [test.basic_joins_md_foreign1]
| filter: { "d" : { "$lt" : 3 } }
| |
| INDEX_PROBE_NODE [test.basic_joins_md_foreign1]
| keyPattern: { "a" : 1 }
| indexName: "a_1"
| isMultiKey: false
| isUnique: false
| isSparse: false
| isPartial: false
|
COLLSCAN [test.basic_joins_md]
filter: { "a" : { "$gt" : 1 } }
direction: "forward"
7. Basic example with referencing field from previous lookup
No join opt
Pipeline
[
{
"$lookup" : {
"from" : "basic_joins_md_foreign1",
"as" : "x",
"localField" : "a",
"foreignField" : "a"
}
},
{
"$unwind" : "$x"
},
{
"$lookup" : {
"from" : "basic_joins_md_foreign3",
"as" : "z",
"localField" : "x.c",
"foreignField" : "c"
}
},
{
"$unwind" : "$z"
}
]
Results
{ "_id" : 0, "a" : 1, "b" : "foo", "x" : { "_id" : 0, "a" : 1, "c" : "zoo", "d" : 1 }, "z" : { "_id" : 0, "a" : 1, "c" : "zoo", "d" : 1 } }
{ "_id" : 1, "a" : 1, "b" : "bar", "x" : { "_id" : 0, "a" : 1, "c" : "zoo", "d" : 1 }, "z" : { "_id" : 0, "a" : 1, "c" : "zoo", "d" : 1 } }
{ "_id" : 2, "a" : 2, "b" : "bar", "x" : { "_id" : 1, "a" : 2, "c" : "blah", "d" : 2 }, "z" : { "_id" : 1, "a" : 2, "c" : "blah", "d" : 2 } }
{ "_id" : 2, "a" : 2, "b" : "bar", "x" : { "_id" : 2, "a" : 2, "c" : "x", "d" : 3 }, "z" : { "_id" : 2, "a" : 2, "c" : "x", "d" : 3 } }
Summarized explain
Execution Engine: sbe
{
"queryShapeHash" : "DC5CAF413E9B6B8B5E8B2D3FB91E4D546524BF2707BBE30472D5CA8E12F6637E",
"rejectedPlans" : [ ],
"winningPlan" : {
"asField" : "z",
"foreignCollection" : "test.basic_joins_md_foreign3",
"foreignField" : "c",
"inputStage" : {
"asField" : "x",
"foreignCollection" : "test.basic_joins_md_foreign1",
"foreignField" : "a",
"inputStage" : {
"direction" : "forward",
"filter" : {
},
"nss" : "test.basic_joins_md",
"stage" : "COLLSCAN"
},
"localField" : "a",
"scanDirection" : "forward",
"stage" : "EQ_LOOKUP_UNWIND",
"strategy" : "HashJoin"
},
"localField" : "x.c",
"planNodeId" : 3,
"scanDirection" : "forward",
"stage" : "EQ_LOOKUP_UNWIND",
"strategy" : "HashJoin"
}
}
With bottom-up plan enumeration (left-deep)
usedJoinOptimization: true
HASH_JOIN_EMBEDDING [x.c = c]
leftEmbeddingField: "none"
rightEmbeddingField: "z"
| |
| COLLSCAN [test.basic_joins_md_foreign3]
| direction: "forward"
|
HASH_JOIN_EMBEDDING [a = a]
leftEmbeddingField: "none"
rightEmbeddingField: "x"
| |
| COLLSCAN [test.basic_joins_md_foreign1]
| direction: "forward"
|
COLLSCAN [test.basic_joins_md]
direction: "forward"
With bottom-up plan enumeration (right-deep)
usedJoinOptimization: true
HASH_JOIN_EMBEDDING [c = x.c]
leftEmbeddingField: "z"
rightEmbeddingField: "none"
| |
| HASH_JOIN_EMBEDDING [a = a]
| leftEmbeddingField: "none"
| rightEmbeddingField: "x"
| | |
| | COLLSCAN [test.basic_joins_md_foreign1]
| | direction: "forward"
| |
| COLLSCAN [test.basic_joins_md]
| direction: "forward"
|
COLLSCAN [test.basic_joins_md_foreign3]
direction: "forward"
With bottom-up plan enumeration (zig-zag)
usedJoinOptimization: true
HASH_JOIN_EMBEDDING [x.c = c]
leftEmbeddingField: "none"
rightEmbeddingField: "z"
| |
| COLLSCAN [test.basic_joins_md_foreign3]
| direction: "forward"
|
HASH_JOIN_EMBEDDING [a = a]
leftEmbeddingField: "none"
rightEmbeddingField: "x"
| |
| COLLSCAN [test.basic_joins_md_foreign1]
| direction: "forward"
|
COLLSCAN [test.basic_joins_md]
direction: "forward"
With random order, seed 44, nested loop joins
usedJoinOptimization: true
NESTED_LOOP_JOIN_EMBEDDING [x.c = c]
leftEmbeddingField: "none"
rightEmbeddingField: "z"
| |
| COLLSCAN [test.basic_joins_md_foreign3]
| direction: "forward"
|
NESTED_LOOP_JOIN_EMBEDDING [a = a]
leftEmbeddingField: "x"
rightEmbeddingField: "none"
| |
| COLLSCAN [test.basic_joins_md]
| direction: "forward"
|
COLLSCAN [test.basic_joins_md_foreign1]
direction: "forward"
With random order, seed 44, hash join enabled
usedJoinOptimization: true
HASH_JOIN_EMBEDDING [x.c = c]
leftEmbeddingField: "none"
rightEmbeddingField: "z"
| |
| COLLSCAN [test.basic_joins_md_foreign3]
| direction: "forward"
|
HASH_JOIN_EMBEDDING [a = a]
leftEmbeddingField: "x"
rightEmbeddingField: "none"
| |
| COLLSCAN [test.basic_joins_md]
| direction: "forward"
|
COLLSCAN [test.basic_joins_md_foreign1]
direction: "forward"
With random order, seed 45, nested loop joins
usedJoinOptimization: true
HASH_JOIN_EMBEDDING [x.a = a]
leftEmbeddingField: "none"
rightEmbeddingField: "none"
| |
| COLLSCAN [test.basic_joins_md]
| direction: "forward"
|
HASH_JOIN_EMBEDDING [c = c]
leftEmbeddingField: "z"
rightEmbeddingField: "x"
| |
| COLLSCAN [test.basic_joins_md_foreign1]
| direction: "forward"
|
COLLSCAN [test.basic_joins_md_foreign3]
direction: "forward"
With random order, seed 45, hash join enabled
usedJoinOptimization: true
HASH_JOIN_EMBEDDING [x.a = a]
leftEmbeddingField: "none"
rightEmbeddingField: "none"
| |
| COLLSCAN [test.basic_joins_md]
| direction: "forward"
|
HASH_JOIN_EMBEDDING [c = c]
leftEmbeddingField: "z"
rightEmbeddingField: "x"
| |
| COLLSCAN [test.basic_joins_md_foreign1]
| direction: "forward"
|
COLLSCAN [test.basic_joins_md_foreign3]
direction: "forward"
With fixed order, index join
usedJoinOptimization: true
NESTED_LOOP_JOIN_EMBEDDING [x.a = a]
leftEmbeddingField: "none"
rightEmbeddingField: "none"
| |
| COLLSCAN [test.basic_joins_md]
| direction: "forward"
|
NESTED_LOOP_JOIN_EMBEDDING [c = c]
leftEmbeddingField: "z"
rightEmbeddingField: "x"
| |
| COLLSCAN [test.basic_joins_md_foreign1]
| direction: "forward"
|
COLLSCAN [test.basic_joins_md_foreign3]
direction: "forward"
With bottom-up plan enumeration and indexes
usedJoinOptimization: true
HASH_JOIN_EMBEDDING [x.c = c]
leftEmbeddingField: "none"
rightEmbeddingField: "z"
| |
| COLLSCAN [test.basic_joins_md_foreign3]
| direction: "forward"
|
INDEXED_NESTED_LOOP_JOIN_EMBEDDING [a = a]
leftEmbeddingField: "none"
rightEmbeddingField: "x"
| |
| FETCH [test.basic_joins_md_foreign1]
|
| |
| INDEX_PROBE_NODE [test.basic_joins_md_foreign1]
| keyPattern: { "a" : 1 }
| indexName: "a_1"
| isMultiKey: false
| isUnique: false
| isSparse: false
| isPartial: false
|
COLLSCAN [test.basic_joins_md]
direction: "forward"
8. Basic example with 3 joins & subsequent join referencing fields from previous lookups
No join opt
Pipeline
[
{
"$lookup" : {
"from" : "basic_joins_md_foreign1",
"as" : "x",
"localField" : "a",
"foreignField" : "a"
}
},
{
"$unwind" : "$x"
},
{
"$lookup" : {
"from" : "basic_joins_md_foreign2",
"as" : "y",
"localField" : "b",
"foreignField" : "b"
}
},
{
"$unwind" : "$y"
},
{
"$lookup" : {
"from" : "basic_joins_md_foreign3",
"as" : "z",
"localField" : "x.c",
"foreignField" : "c"
}
},
{
"$unwind" : "$z"
}
]
Results
{ "_id" : 1, "a" : 1, "b" : "bar", "x" : { "_id" : 0, "a" : 1, "c" : "zoo", "d" : 1 }, "y" : { "_id" : 0, "b" : "bar", "d" : 2 }, "z" : { "_id" : 0, "a" : 1, "c" : "zoo", "d" : 1 } }
{ "_id" : 1, "a" : 1, "b" : "bar", "x" : { "_id" : 0, "a" : 1, "c" : "zoo", "d" : 1 }, "y" : { "_id" : 1, "b" : "bar", "d" : 6 }, "z" : { "_id" : 0, "a" : 1, "c" : "zoo", "d" : 1 } }
{ "_id" : 2, "a" : 2, "b" : "bar", "x" : { "_id" : 1, "a" : 2, "c" : "blah", "d" : 2 }, "y" : { "_id" : 0, "b" : "bar", "d" : 2 }, "z" : { "_id" : 1, "a" : 2, "c" : "blah", "d" : 2 } }
{ "_id" : 2, "a" : 2, "b" : "bar", "x" : { "_id" : 1, "a" : 2, "c" : "blah", "d" : 2 }, "y" : { "_id" : 1, "b" : "bar", "d" : 6 }, "z" : { "_id" : 1, "a" : 2, "c" : "blah", "d" : 2 } }
{ "_id" : 2, "a" : 2, "b" : "bar", "x" : { "_id" : 2, "a" : 2, "c" : "x", "d" : 3 }, "y" : { "_id" : 0, "b" : "bar", "d" : 2 }, "z" : { "_id" : 2, "a" : 2, "c" : "x", "d" : 3 } }
{ "_id" : 2, "a" : 2, "b" : "bar", "x" : { "_id" : 2, "a" : 2, "c" : "x", "d" : 3 }, "y" : { "_id" : 1, "b" : "bar", "d" : 6 }, "z" : { "_id" : 2, "a" : 2, "c" : "x", "d" : 3 } }
Summarized explain
Execution Engine: sbe
{
"queryShapeHash" : "DD24FFAE1F16C6C1F5B03939E0C642A797120A2585058C72554C9649BEA427AB",
"rejectedPlans" : [ ],
"winningPlan" : {
"asField" : "z",
"foreignCollection" : "test.basic_joins_md_foreign3",
"foreignField" : "c",
"inputStage" : {
"asField" : "y",
"foreignCollection" : "test.basic_joins_md_foreign2",
"foreignField" : "b",
"inputStage" : {
"asField" : "x",
"foreignCollection" : "test.basic_joins_md_foreign1",
"foreignField" : "a",
"inputStage" : {
"direction" : "forward",
"filter" : {
},
"nss" : "test.basic_joins_md",
"stage" : "COLLSCAN"
},
"localField" : "a",
"scanDirection" : "forward",
"stage" : "EQ_LOOKUP_UNWIND",
"strategy" : "HashJoin"
},
"localField" : "b",
"scanDirection" : "forward",
"stage" : "EQ_LOOKUP_UNWIND",
"strategy" : "HashJoin"
},
"localField" : "x.c",
"planNodeId" : 4,
"scanDirection" : "forward",
"stage" : "EQ_LOOKUP_UNWIND",
"strategy" : "HashJoin"
}
}
With bottom-up plan enumeration (left-deep)
usedJoinOptimization: true
HASH_JOIN_EMBEDDING [x.c = c]
leftEmbeddingField: "none"
rightEmbeddingField: "z"
| |
| COLLSCAN [test.basic_joins_md_foreign3]
| direction: "forward"
|
HASH_JOIN_EMBEDDING [b = b]
leftEmbeddingField: "none"
rightEmbeddingField: "y"
| |
| COLLSCAN [test.basic_joins_md_foreign2]
| direction: "forward"
|
HASH_JOIN_EMBEDDING [a = a]
leftEmbeddingField: "none"
rightEmbeddingField: "x"
| |
| COLLSCAN [test.basic_joins_md_foreign1]
| direction: "forward"
|
COLLSCAN [test.basic_joins_md]
direction: "forward"
With bottom-up plan enumeration (right-deep)
usedJoinOptimization: true
HASH_JOIN_EMBEDDING [c = x.c]
leftEmbeddingField: "z"
rightEmbeddingField: "none"
| |
| HASH_JOIN_EMBEDDING [b = b]
| leftEmbeddingField: "y"
| rightEmbeddingField: "none"
| | |
| | HASH_JOIN_EMBEDDING [a = a]
| | leftEmbeddingField: "none"
| | rightEmbeddingField: "x"
| | | |
| | | COLLSCAN [test.basic_joins_md_foreign1]
| | | direction: "forward"
| | |
| | COLLSCAN [test.basic_joins_md]
| | direction: "forward"
| |
| COLLSCAN [test.basic_joins_md_foreign2]
| direction: "forward"
|
COLLSCAN [test.basic_joins_md_foreign3]
direction: "forward"
With bottom-up plan enumeration (zig-zag)
usedJoinOptimization: true
HASH_JOIN_EMBEDDING [c = x.c]
leftEmbeddingField: "z"
rightEmbeddingField: "none"
| |
| HASH_JOIN_EMBEDDING [b = b]
| leftEmbeddingField: "none"
| rightEmbeddingField: "y"
| | |
| | COLLSCAN [test.basic_joins_md_foreign2]
| | direction: "forward"
| |
| HASH_JOIN_EMBEDDING [a = a]
| leftEmbeddingField: "none"
| rightEmbeddingField: "x"
| | |
| | COLLSCAN [test.basic_joins_md_foreign1]
| | direction: "forward"
| |
| COLLSCAN [test.basic_joins_md]
| direction: "forward"
|
COLLSCAN [test.basic_joins_md_foreign3]
direction: "forward"
With random order, seed 44, nested loop joins
usedJoinOptimization: true
NESTED_LOOP_JOIN_EMBEDDING [b = b]
leftEmbeddingField: "none"
rightEmbeddingField: "y"
| |
| COLLSCAN [test.basic_joins_md_foreign2]
| direction: "forward"
|
NESTED_LOOP_JOIN_EMBEDDING [x.c = c]
leftEmbeddingField: "none"
rightEmbeddingField: "z"
| |
| COLLSCAN [test.basic_joins_md_foreign3]
| direction: "forward"
|
NESTED_LOOP_JOIN_EMBEDDING [a = a]
leftEmbeddingField: "none"
rightEmbeddingField: "x"
| |
| COLLSCAN [test.basic_joins_md_foreign1]
| direction: "forward"
|
COLLSCAN [test.basic_joins_md]
direction: "forward"
With random order, seed 44, hash join enabled
usedJoinOptimization: true
HASH_JOIN_EMBEDDING [b = b]
leftEmbeddingField: "none"
rightEmbeddingField: "y"
| |
| COLLSCAN [test.basic_joins_md_foreign2]
| direction: "forward"
|
HASH_JOIN_EMBEDDING [x.c = c]
leftEmbeddingField: "none"
rightEmbeddingField: "z"
| |
| COLLSCAN [test.basic_joins_md_foreign3]
| direction: "forward"
|
HASH_JOIN_EMBEDDING [a = a]
leftEmbeddingField: "none"
rightEmbeddingField: "x"
| |
| COLLSCAN [test.basic_joins_md_foreign1]
| direction: "forward"
|
COLLSCAN [test.basic_joins_md]
direction: "forward"
With random order, seed 45, nested loop joins
usedJoinOptimization: true
HASH_JOIN_EMBEDDING [b = b]
leftEmbeddingField: "none"
rightEmbeddingField: "y"
| |
| COLLSCAN [test.basic_joins_md_foreign2]
| direction: "forward"
|
HASH_JOIN_EMBEDDING [x.a = a]
leftEmbeddingField: "none"
rightEmbeddingField: "none"
| |
| COLLSCAN [test.basic_joins_md]
| direction: "forward"
|
HASH_JOIN_EMBEDDING [c = c]
leftEmbeddingField: "z"
rightEmbeddingField: "x"
| |
| COLLSCAN [test.basic_joins_md_foreign1]
| direction: "forward"
|
COLLSCAN [test.basic_joins_md_foreign3]
direction: "forward"
With random order, seed 45, hash join enabled
usedJoinOptimization: true
HASH_JOIN_EMBEDDING [b = b]
leftEmbeddingField: "none"
rightEmbeddingField: "y"
| |
| COLLSCAN [test.basic_joins_md_foreign2]
| direction: "forward"
|
HASH_JOIN_EMBEDDING [x.a = a]
leftEmbeddingField: "none"
rightEmbeddingField: "none"
| |
| COLLSCAN [test.basic_joins_md]
| direction: "forward"
|
HASH_JOIN_EMBEDDING [c = c]
leftEmbeddingField: "z"
rightEmbeddingField: "x"
| |
| COLLSCAN [test.basic_joins_md_foreign1]
| direction: "forward"
|
COLLSCAN [test.basic_joins_md_foreign3]
direction: "forward"
With fixed order, index join
usedJoinOptimization: true
INDEXED_NESTED_LOOP_JOIN_EMBEDDING [b = b]
leftEmbeddingField: "none"
rightEmbeddingField: "y"
| |
| FETCH [test.basic_joins_md_foreign2]
|
| |
| INDEX_PROBE_NODE [test.basic_joins_md_foreign2]
| keyPattern: { "b" : 1 }
| indexName: "b_1"
| isMultiKey: false
| isUnique: false
| isSparse: false
| isPartial: false
|
NESTED_LOOP_JOIN_EMBEDDING [x.a = a]
leftEmbeddingField: "none"
rightEmbeddingField: "none"
| |
| COLLSCAN [test.basic_joins_md]
| direction: "forward"
|
NESTED_LOOP_JOIN_EMBEDDING [c = c]
leftEmbeddingField: "z"
rightEmbeddingField: "x"
| |
| COLLSCAN [test.basic_joins_md_foreign1]
| direction: "forward"
|
COLLSCAN [test.basic_joins_md_foreign3]
direction: "forward"
With bottom-up plan enumeration and indexes
usedJoinOptimization: true
HASH_JOIN_EMBEDDING [x.c = c]
leftEmbeddingField: "none"
rightEmbeddingField: "z"
| |
| COLLSCAN [test.basic_joins_md_foreign3]
| direction: "forward"
|
INDEXED_NESTED_LOOP_JOIN_EMBEDDING [b = b]
leftEmbeddingField: "none"
rightEmbeddingField: "y"
| |
| FETCH [test.basic_joins_md_foreign2]
|
| |
| INDEX_PROBE_NODE [test.basic_joins_md_foreign2]
| keyPattern: { "b" : 1 }
| indexName: "b_1"
| isMultiKey: false
| isUnique: false
| isSparse: false
| isPartial: false
|
INDEXED_NESTED_LOOP_JOIN_EMBEDDING [a = a]
leftEmbeddingField: "none"
rightEmbeddingField: "x"
| |
| FETCH [test.basic_joins_md_foreign1]
|
| |
| INDEX_PROBE_NODE [test.basic_joins_md_foreign1]
| keyPattern: { "a" : 1 }
| indexName: "a_1"
| isMultiKey: false
| isUnique: false
| isSparse: false
| isPartial: false
|
COLLSCAN [test.basic_joins_md]
direction: "forward"
9. Basic example with 3 joins & subsequent join referencing nested paths
No join opt
Pipeline
[
{
"$lookup" : {
"from" : "basic_joins_md_foreign1",
"as" : "x",
"localField" : "a",
"foreignField" : "a"
}
},
{
"$unwind" : "$x"
},
{
"$lookup" : {
"from" : "basic_joins_md_foreign3",
"as" : "w.y",
"localField" : "x.c",
"foreignField" : "c"
}
},
{
"$unwind" : "$w.y"
},
{
"$lookup" : {
"from" : "basic_joins_md_foreign2",
"as" : "k.y.z",
"localField" : "w.y.d",
"foreignField" : "d"
}
},
{
"$unwind" : "$k.y.z"
}
]
Results
{ "_id" : 2, "a" : 2, "b" : "bar", "k" : { "y" : { "z" : { "_id" : 0, "b" : "bar", "d" : 2 } } }, "w" : { "y" : { "_id" : 1, "a" : 2, "c" : "blah", "d" : 2 } }, "x" : { "_id" : 1, "a" : 2, "c" : "blah", "d" : 2 } }
Summarized explain
Execution Engine: sbe
{
"queryShapeHash" : "9226A4FAA10C8790B27D9B5B865D46D0C58179A837F014E6289A34A6EBE76420",
"rejectedPlans" : [ ],
"winningPlan" : {
"asField" : "k.y.z",
"foreignCollection" : "test.basic_joins_md_foreign2",
"foreignField" : "d",
"inputStage" : {
"asField" : "w.y",
"foreignCollection" : "test.basic_joins_md_foreign3",
"foreignField" : "c",
"inputStage" : {
"asField" : "x",
"foreignCollection" : "test.basic_joins_md_foreign1",
"foreignField" : "a",
"inputStage" : {
"direction" : "forward",
"filter" : {
},
"nss" : "test.basic_joins_md",
"stage" : "COLLSCAN"
},
"localField" : "a",
"scanDirection" : "forward",
"stage" : "EQ_LOOKUP_UNWIND",
"strategy" : "HashJoin"
},
"localField" : "x.c",
"scanDirection" : "forward",
"stage" : "EQ_LOOKUP_UNWIND",
"strategy" : "HashJoin"
},
"localField" : "w.y.d",
"planNodeId" : 4,
"scanDirection" : "forward",
"stage" : "EQ_LOOKUP_UNWIND",
"strategy" : "HashJoin"
}
}
With bottom-up plan enumeration (left-deep)
usedJoinOptimization: true
HASH_JOIN_EMBEDDING [w.y.d = d]
leftEmbeddingField: "none"
rightEmbeddingField: "k.y.z"
| |
| COLLSCAN [test.basic_joins_md_foreign2]
| direction: "forward"
|
HASH_JOIN_EMBEDDING [x.c = c]
leftEmbeddingField: "none"
rightEmbeddingField: "w.y"
| |
| COLLSCAN [test.basic_joins_md_foreign3]
| direction: "forward"
|
HASH_JOIN_EMBEDDING [a = a]
leftEmbeddingField: "none"
rightEmbeddingField: "x"
| |
| COLLSCAN [test.basic_joins_md_foreign1]
| direction: "forward"
|
COLLSCAN [test.basic_joins_md]
direction: "forward"
With bottom-up plan enumeration (right-deep)
usedJoinOptimization: true
HASH_JOIN_EMBEDDING [d = w.y.d]
leftEmbeddingField: "k.y.z"
rightEmbeddingField: "none"
| |
| HASH_JOIN_EMBEDDING [c = x.c]
| leftEmbeddingField: "w.y"
| rightEmbeddingField: "none"
| | |
| | HASH_JOIN_EMBEDDING [a = a]
| | leftEmbeddingField: "none"
| | rightEmbeddingField: "x"
| | | |
| | | COLLSCAN [test.basic_joins_md_foreign1]
| | | direction: "forward"
| | |
| | COLLSCAN [test.basic_joins_md]
| | direction: "forward"
| |
| COLLSCAN [test.basic_joins_md_foreign3]
| direction: "forward"
|
COLLSCAN [test.basic_joins_md_foreign2]
direction: "forward"
With bottom-up plan enumeration (zig-zag)
usedJoinOptimization: true
HASH_JOIN_EMBEDDING [d = w.y.d]
leftEmbeddingField: "k.y.z"
rightEmbeddingField: "none"
| |
| HASH_JOIN_EMBEDDING [x.c = c]
| leftEmbeddingField: "none"
| rightEmbeddingField: "w.y"
| | |
| | COLLSCAN [test.basic_joins_md_foreign3]
| | direction: "forward"
| |
| HASH_JOIN_EMBEDDING [a = a]
| leftEmbeddingField: "none"
| rightEmbeddingField: "x"
| | |
| | COLLSCAN [test.basic_joins_md_foreign1]
| | direction: "forward"
| |
| COLLSCAN [test.basic_joins_md]
| direction: "forward"
|
COLLSCAN [test.basic_joins_md_foreign2]
direction: "forward"
With random order, seed 44, nested loop joins
usedJoinOptimization: true
NESTED_LOOP_JOIN_EMBEDDING [w.y.d = d]
leftEmbeddingField: "none"
rightEmbeddingField: "k.y.z"
| |
| COLLSCAN [test.basic_joins_md_foreign2]
| direction: "forward"
|
NESTED_LOOP_JOIN_EMBEDDING [x.c = c]
leftEmbeddingField: "none"
rightEmbeddingField: "w.y"
| |
| COLLSCAN [test.basic_joins_md_foreign3]
| direction: "forward"
|
NESTED_LOOP_JOIN_EMBEDDING [a = a]
leftEmbeddingField: "none"
rightEmbeddingField: "x"
| |
| COLLSCAN [test.basic_joins_md_foreign1]
| direction: "forward"
|
COLLSCAN [test.basic_joins_md]
direction: "forward"
With random order, seed 44, hash join enabled
usedJoinOptimization: true
HASH_JOIN_EMBEDDING [w.y.d = d]
leftEmbeddingField: "none"
rightEmbeddingField: "k.y.z"
| |
| COLLSCAN [test.basic_joins_md_foreign2]
| direction: "forward"
|
HASH_JOIN_EMBEDDING [x.c = c]
leftEmbeddingField: "none"
rightEmbeddingField: "w.y"
| |
| COLLSCAN [test.basic_joins_md_foreign3]
| direction: "forward"
|
HASH_JOIN_EMBEDDING [a = a]
leftEmbeddingField: "none"
rightEmbeddingField: "x"
| |
| COLLSCAN [test.basic_joins_md_foreign1]
| direction: "forward"
|
COLLSCAN [test.basic_joins_md]
direction: "forward"
With random order, seed 45, nested loop joins
usedJoinOptimization: true
HASH_JOIN_EMBEDDING [x.a = a]
leftEmbeddingField: "none"
rightEmbeddingField: "none"
| |
| COLLSCAN [test.basic_joins_md]
| direction: "forward"
|
HASH_JOIN_EMBEDDING [w.y.c = c]
leftEmbeddingField: "none"
rightEmbeddingField: "x"
| |
| COLLSCAN [test.basic_joins_md_foreign1]
| direction: "forward"
|
HASH_JOIN_EMBEDDING [d = d]
leftEmbeddingField: "k.y.z"
rightEmbeddingField: "w.y"
| |
| COLLSCAN [test.basic_joins_md_foreign3]
| direction: "forward"
|
COLLSCAN [test.basic_joins_md_foreign2]
direction: "forward"
With random order, seed 45, hash join enabled
usedJoinOptimization: true
HASH_JOIN_EMBEDDING [x.a = a]
leftEmbeddingField: "none"
rightEmbeddingField: "none"
| |
| COLLSCAN [test.basic_joins_md]
| direction: "forward"
|
HASH_JOIN_EMBEDDING [w.y.c = c]
leftEmbeddingField: "none"
rightEmbeddingField: "x"
| |
| COLLSCAN [test.basic_joins_md_foreign1]
| direction: "forward"
|
HASH_JOIN_EMBEDDING [d = d]
leftEmbeddingField: "k.y.z"
rightEmbeddingField: "w.y"
| |
| COLLSCAN [test.basic_joins_md_foreign3]
| direction: "forward"
|
COLLSCAN [test.basic_joins_md_foreign2]
direction: "forward"
With fixed order, index join
usedJoinOptimization: true
NESTED_LOOP_JOIN_EMBEDDING [x.a = a]
leftEmbeddingField: "none"
rightEmbeddingField: "none"
| |
| COLLSCAN [test.basic_joins_md]
| direction: "forward"
|
NESTED_LOOP_JOIN_EMBEDDING [w.y.c = c]
leftEmbeddingField: "none"
rightEmbeddingField: "x"
| |
| COLLSCAN [test.basic_joins_md_foreign1]
| direction: "forward"
|
NESTED_LOOP_JOIN_EMBEDDING [d = d]
leftEmbeddingField: "k.y.z"
rightEmbeddingField: "w.y"
| |
| COLLSCAN [test.basic_joins_md_foreign3]
| direction: "forward"
|
COLLSCAN [test.basic_joins_md_foreign2]
direction: "forward"
With bottom-up plan enumeration and indexes
usedJoinOptimization: true
HASH_JOIN_EMBEDDING [w.y.d = d]
leftEmbeddingField: "none"
rightEmbeddingField: "k.y.z"
| |
| COLLSCAN [test.basic_joins_md_foreign2]
| direction: "forward"
|
HASH_JOIN_EMBEDDING [x.c = c]
leftEmbeddingField: "none"
rightEmbeddingField: "w.y"
| |
| COLLSCAN [test.basic_joins_md_foreign3]
| direction: "forward"
|
INDEXED_NESTED_LOOP_JOIN_EMBEDDING [a = a]
leftEmbeddingField: "none"
rightEmbeddingField: "x"
| |
| FETCH [test.basic_joins_md_foreign1]
|
| |
| INDEX_PROBE_NODE [test.basic_joins_md_foreign1]
| keyPattern: { "a" : 1 }
| indexName: "a_1"
| isMultiKey: false
| isUnique: false
| isSparse: false
| isPartial: false
|
COLLSCAN [test.basic_joins_md]
direction: "forward"
10. Basic example with a $project excluding a field from the base collection
No join opt
Pipeline
[
{
"$project" : {
"_id" : false
}
},
{
"$lookup" : {
"from" : "basic_joins_md_foreign1",
"as" : "x",
"localField" : "a",
"foreignField" : "a"
}
},
{
"$unwind" : "$x"
},
{
"$lookup" : {
"from" : "basic_joins_md_foreign2",
"as" : "y",
"localField" : "b",
"foreignField" : "b"
}
},
{
"$unwind" : "$y"
}
]
Results
{ "a" : 1, "b" : "bar", "x" : { "_id" : 0, "a" : 1, "c" : "zoo", "d" : 1 }, "y" : { "_id" : 0, "b" : "bar", "d" : 2 } }
{ "a" : 1, "b" : "bar", "x" : { "_id" : 0, "a" : 1, "c" : "zoo", "d" : 1 }, "y" : { "_id" : 1, "b" : "bar", "d" : 6 } }
{ "a" : 2, "b" : "bar", "x" : { "_id" : 1, "a" : 2, "c" : "blah", "d" : 2 }, "y" : { "_id" : 0, "b" : "bar", "d" : 2 } }
{ "a" : 2, "b" : "bar", "x" : { "_id" : 1, "a" : 2, "c" : "blah", "d" : 2 }, "y" : { "_id" : 1, "b" : "bar", "d" : 6 } }
{ "a" : 2, "b" : "bar", "x" : { "_id" : 2, "a" : 2, "c" : "x", "d" : 3 }, "y" : { "_id" : 0, "b" : "bar", "d" : 2 } }
{ "a" : 2, "b" : "bar", "x" : { "_id" : 2, "a" : 2, "c" : "x", "d" : 3 }, "y" : { "_id" : 1, "b" : "bar", "d" : 6 } }
Summarized explain
Execution Engine: sbe
{
"queryShapeHash" : "9A2C9BDFA638F0C7F703251AC894A297CDDB8AF81B931E490B488BCF87386796",
"rejectedPlans" : [ ],
"winningPlan" : {
"asField" : "y",
"foreignCollection" : "test.basic_joins_md_foreign2",
"foreignField" : "b",
"inputStage" : {
"asField" : "x",
"foreignCollection" : "test.basic_joins_md_foreign1",
"foreignField" : "a",
"inputStage" : {
"inputStage" : {
"direction" : "forward",
"filter" : {
},
"nss" : "test.basic_joins_md",
"stage" : "COLLSCAN"
},
"stage" : "PROJECTION_SIMPLE",
"transformBy" : {
"_id" : false
}
},
"localField" : "a",
"scanDirection" : "forward",
"stage" : "EQ_LOOKUP_UNWIND",
"strategy" : "HashJoin"
},
"localField" : "b",
"planNodeId" : 4,
"scanDirection" : "forward",
"stage" : "EQ_LOOKUP_UNWIND",
"strategy" : "HashJoin"
}
}
With bottom-up plan enumeration (left-deep)
usedJoinOptimization: true
HASH_JOIN_EMBEDDING [b = b]
leftEmbeddingField: "none"
rightEmbeddingField: "y"
| |
| COLLSCAN [test.basic_joins_md_foreign2]
| direction: "forward"
|
HASH_JOIN_EMBEDDING [a = a]
leftEmbeddingField: "none"
rightEmbeddingField: "x"
| |
| COLLSCAN [test.basic_joins_md_foreign1]
| direction: "forward"
|
PROJECTION_SIMPLE
transformBy: { "_id" : false }
|
COLLSCAN [test.basic_joins_md]
direction: "forward"
With bottom-up plan enumeration (right-deep)
usedJoinOptimization: true
HASH_JOIN_EMBEDDING [b = b]
leftEmbeddingField: "y"
rightEmbeddingField: "none"
| |
| HASH_JOIN_EMBEDDING [a = a]
| leftEmbeddingField: "none"
| rightEmbeddingField: "x"
| | |
| | COLLSCAN [test.basic_joins_md_foreign1]
| | direction: "forward"
| |
| PROJECTION_SIMPLE
| transformBy: { "_id" : false }
| |
| COLLSCAN [test.basic_joins_md]
| direction: "forward"
|
COLLSCAN [test.basic_joins_md_foreign2]
direction: "forward"
With bottom-up plan enumeration (zig-zag)
usedJoinOptimization: true
HASH_JOIN_EMBEDDING [b = b]
leftEmbeddingField: "none"
rightEmbeddingField: "y"
| |
| COLLSCAN [test.basic_joins_md_foreign2]
| direction: "forward"
|
HASH_JOIN_EMBEDDING [a = a]
leftEmbeddingField: "none"
rightEmbeddingField: "x"
| |
| COLLSCAN [test.basic_joins_md_foreign1]
| direction: "forward"
|
PROJECTION_SIMPLE
transformBy: { "_id" : false }
|
COLLSCAN [test.basic_joins_md]
direction: "forward"
With random order, seed 44, nested loop joins
usedJoinOptimization: true
NESTED_LOOP_JOIN_EMBEDDING [b = b]
leftEmbeddingField: "none"
rightEmbeddingField: "y"
| |
| COLLSCAN [test.basic_joins_md_foreign2]
| direction: "forward"
|
NESTED_LOOP_JOIN_EMBEDDING [a = a]
leftEmbeddingField: "x"
rightEmbeddingField: "none"
| |
| PROJECTION_SIMPLE
| transformBy: { "_id" : false }
| |
| COLLSCAN [test.basic_joins_md]
| direction: "forward"
|
COLLSCAN [test.basic_joins_md_foreign1]
direction: "forward"
With random order, seed 44, hash join enabled
usedJoinOptimization: true
HASH_JOIN_EMBEDDING [b = b]
leftEmbeddingField: "none"
rightEmbeddingField: "y"
| |
| COLLSCAN [test.basic_joins_md_foreign2]
| direction: "forward"
|
HASH_JOIN_EMBEDDING [a = a]
leftEmbeddingField: "x"
rightEmbeddingField: "none"
| |
| PROJECTION_SIMPLE
| transformBy: { "_id" : false }
| |
| COLLSCAN [test.basic_joins_md]
| direction: "forward"
|
COLLSCAN [test.basic_joins_md_foreign1]
direction: "forward"
With random order, seed 45, nested loop joins
usedJoinOptimization: true
HASH_JOIN_EMBEDDING [a = a]
leftEmbeddingField: "none"
rightEmbeddingField: "x"
| |
| COLLSCAN [test.basic_joins_md_foreign1]
| direction: "forward"
|
HASH_JOIN_EMBEDDING [b = b]
leftEmbeddingField: "y"
rightEmbeddingField: "none"
| |
| PROJECTION_SIMPLE
| transformBy: { "_id" : false }
| |
| COLLSCAN [test.basic_joins_md]
| direction: "forward"
|
COLLSCAN [test.basic_joins_md_foreign2]
direction: "forward"
With random order, seed 45, hash join enabled
usedJoinOptimization: true
HASH_JOIN_EMBEDDING [a = a]
leftEmbeddingField: "none"
rightEmbeddingField: "x"
| |
| COLLSCAN [test.basic_joins_md_foreign1]
| direction: "forward"
|
HASH_JOIN_EMBEDDING [b = b]
leftEmbeddingField: "y"
rightEmbeddingField: "none"
| |
| PROJECTION_SIMPLE
| transformBy: { "_id" : false }
| |
| COLLSCAN [test.basic_joins_md]
| direction: "forward"
|
COLLSCAN [test.basic_joins_md_foreign2]
direction: "forward"
With fixed order, index join
usedJoinOptimization: true
INDEXED_NESTED_LOOP_JOIN_EMBEDDING [a = a]
leftEmbeddingField: "none"
rightEmbeddingField: "x"
| |
| FETCH [test.basic_joins_md_foreign1]
|
| |
| INDEX_PROBE_NODE [test.basic_joins_md_foreign1]
| keyPattern: { "a" : 1 }
| indexName: "a_1"
| isMultiKey: false
| isUnique: false
| isSparse: false
| isPartial: false
|
NESTED_LOOP_JOIN_EMBEDDING [b = b]
leftEmbeddingField: "y"
rightEmbeddingField: "none"
| |
| PROJECTION_SIMPLE
| transformBy: { "_id" : false }
| |
| COLLSCAN [test.basic_joins_md]
| direction: "forward"
|
COLLSCAN [test.basic_joins_md_foreign2]
direction: "forward"
With bottom-up plan enumeration and indexes
usedJoinOptimization: true
INDEXED_NESTED_LOOP_JOIN_EMBEDDING [b = b]
leftEmbeddingField: "none"
rightEmbeddingField: "y"
| |
| FETCH [test.basic_joins_md_foreign2]
|
| |
| INDEX_PROBE_NODE [test.basic_joins_md_foreign2]
| keyPattern: { "b" : 1 }
| indexName: "b_1"
| isMultiKey: false
| isUnique: false
| isSparse: false
| isPartial: false
|
INDEXED_NESTED_LOOP_JOIN_EMBEDDING [a = a]
leftEmbeddingField: "none"
rightEmbeddingField: "x"
| |
| FETCH [test.basic_joins_md_foreign1]
|
| |
| INDEX_PROBE_NODE [test.basic_joins_md_foreign1]
| keyPattern: { "a" : 1 }
| indexName: "a_1"
| isMultiKey: false
| isUnique: false
| isSparse: false
| isPartial: false
|
PROJECTION_SIMPLE
transformBy: { "_id" : false }
|
COLLSCAN [test.basic_joins_md]
direction: "forward"