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optimize for the last step of go n steps plan (#4690)
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* optimize for the last step of go n steps plan

* improve some comments
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@jievince
jievince committed Oct 8, 2022
1 parent d67cc4b commit 444a1f1
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Showing 6 changed files with 115 additions and 22 deletions.
5 changes: 4 additions & 1 deletion src/graph/context/ast/QueryAstContext.h
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Original file line number Diff line number Diff line change
Expand Up @@ -93,8 +93,11 @@ struct GoContext final : AstContext {
bool joinInput{false};
// true when $$.tag.prop exist
bool joinDst{false};
// true when yield clause only yield distinct dst id
bool onlyYieldDistinctDstId{false};
// true when edge props only use dst id
bool edgePropsOnlyUseDstId{false};
// Optimize for some simple go sentence which only need dst id.
// eg. GO 1 TO N STEPS FROM "A" OVER like YIELD DISTINCT like._dst
bool isSimple{false};

ExpressionProps exprProps;
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2 changes: 1 addition & 1 deletion src/graph/executor/query/GetDstBySrcExecutor.h
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Expand Up @@ -8,7 +8,7 @@
#include "graph/executor/StorageAccessExecutor.h"
#include "graph/planner/plan/Query.h"

// get the dst id of the src id
// Get the dst id of the src id. The dst is is partially deduplicated on the storage side.
namespace nebula {
namespace graph {
class GetDstBySrcExecutor final : public StorageAccessExecutor {
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65 changes: 46 additions & 19 deletions src/graph/planner/ngql/GoPlanner.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -310,41 +310,53 @@ PlanNode* GoPlanner::buildLastStepJoinPlan(PlanNode* gn, PlanNode* join) {
PlanNode* GoPlanner::lastStep(PlanNode* dep, PlanNode* join) {
auto qctx = goCtx_->qctx;
PlanNode* scan = nullptr;
if (goCtx_->isSimple) {

if (!goCtx_->joinInput && goCtx_->limits.empty() && goCtx_->onlyYieldDistinctDstId &&
!goCtx_->exprProps.hasSrcTagProperty() && goCtx_->edgePropsOnlyUseDstId) {
auto* gd = GetDstBySrc::make(qctx, dep, goCtx_->space.id);
gd->setSrc(goCtx_->from.src);
gd->setEdgeTypes(buildEdgeTypes());
gd->setInputVar(goCtx_->vidsVar);
gd->setColNames({kDst});
scan = gd;
gd->setColNames(goCtx_->colNames);
auto* dedup = Dedup::make(qctx, gd);
dedup->setColNames(goCtx_->colNames);
scan = dedup;

auto* root = goCtx_->joinDst ? buildJoinDstPlan(scan) : scan;
if (goCtx_->filter != nullptr) {
root = Filter::make(qctx, root, goCtx_->filter);
}
if (goCtx_->joinDst) {
goCtx_->yieldExpr->columns()[0]->setExpr(ColumnExpression::make(qctx->objPool(), 0));
root = Project::make(qctx, root, goCtx_->yieldExpr);
}
root->setColNames(std::move(goCtx_->colNames));
return root;
} else {
auto* gn = GetNeighbors::make(qctx, dep, goCtx_->space.id);
gn->setSrc(goCtx_->from.src);
gn->setVertexProps(buildVertexProps(goCtx_->exprProps.srcTagProps()));
gn->setEdgeProps(buildEdgeProps(false));
gn->setInputVar(goCtx_->vidsVar);
scan = gn;
}

const auto& steps = goCtx_->steps;
auto* sampleLimit = buildSampleLimit(scan, steps.isMToN() ? steps.nSteps() : steps.steps());
const auto& steps = goCtx_->steps;
auto* sampleLimit = buildSampleLimit(scan, steps.isMToN() ? steps.nSteps() : steps.steps());

auto* root = buildLastStepJoinPlan(sampleLimit, join);
auto* root = buildLastStepJoinPlan(sampleLimit, join);

if (goCtx_->filter != nullptr) {
root = Filter::make(qctx, root, goCtx_->filter);
}
if (goCtx_->filter != nullptr) {
root = Filter::make(qctx, root, goCtx_->filter);
}

if (!goCtx_->isSimple) {
root = Project::make(qctx, root, goCtx_->yieldExpr);
}
root->setColNames(std::move(goCtx_->colNames));
root->setColNames(std::move(goCtx_->colNames));

if (goCtx_->distinct) {
root = Dedup::make(qctx, root);
if (goCtx_->distinct) {
root = Dedup::make(qctx, root);
}
return root;
}

return root;
}

PlanNode* GoPlanner::buildOneStepJoinPlan(PlanNode* gn) {
Expand Down Expand Up @@ -595,6 +607,8 @@ StatusOr<SubPlan> GoPlanner::transform(AstContext* astCtx) {
auto qctx = goCtx_->qctx;
goCtx_->joinInput = goCtx_->from.fromType != FromType::kInstantExpr;
goCtx_->joinDst = !goCtx_->exprProps.dstTagProps().empty();
goCtx_->onlyYieldDistinctDstId = onlyYieldDistinctDstId();
goCtx_->edgePropsOnlyUseDstId = edgePropsOnlyUseDstId();
goCtx_->isSimple = isSimpleCase();
if (goCtx_->isSimple) {
// We don't need to do a inner join in such case.
Expand Down Expand Up @@ -626,18 +640,31 @@ StatusOr<SubPlan> GoPlanner::transform(AstContext* astCtx) {
}

bool GoPlanner::isSimpleCase() {
if (goCtx_->joinDst || goCtx_->filter || !goCtx_->distinct || !goCtx_->limits.empty()) {
if (!goCtx_->onlyYieldDistinctDstId) {
return false;
}
if (goCtx_->joinDst || goCtx_->filter || !goCtx_->limits.empty()) {
return false;
}
auto& exprProps = goCtx_->exprProps;
if (!exprProps.srcTagProps().empty()) return false;
if (!exprProps.dstTagProps().empty()) return false;
for (auto& edgeProp : exprProps.edgeProps()) {

return goCtx_->edgePropsOnlyUseDstId;
}

bool GoPlanner::edgePropsOnlyUseDstId() {
for (auto& edgeProp : goCtx_->exprProps.edgeProps()) {
auto props = edgeProp.second;
if (props.size() != 1) return false;
if (props.find(kDst) == props.end()) return false;
}

return true;
}

bool GoPlanner::onlyYieldDistinctDstId() {
if (!goCtx_->distinct) return false;
if (goCtx_->yieldExpr->columns().size() != 1) {
return false;
}
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2 changes: 2 additions & 0 deletions src/graph/planner/ngql/GoPlanner.h
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Original file line number Diff line number Diff line change
Expand Up @@ -90,6 +90,8 @@ class GoPlanner final : public Planner {
Expression* stepSampleLimit();

bool isSimpleCase();
bool edgePropsOnlyUseDstId();
bool onlyYieldDistinctDstId();
std::vector<EdgeType> buildEdgeTypes();

private:
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4 changes: 4 additions & 0 deletions src/graph/visitor/DeducePropsVisitor.h
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Original file line number Diff line number Diff line change
Expand Up @@ -54,6 +54,10 @@ class ExpressionProps final {
return !inputProps_.empty() || !varProps_.empty();
}

bool hasSrcTagProperty() const {
return !srcTagProps_.empty();
}

bool hasSrcDstTagProperty() const {
return !srcTagProps_.empty() || !dstTagProps_.empty();
}
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59 changes: 58 additions & 1 deletion tests/tck/features/go/SimpleCase.feature
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Original file line number Diff line number Diff line change
Expand Up @@ -39,7 +39,46 @@ Feature: Simple case
| 2 | GetDstBySrc | 1 | |
| 1 | Start | | |
| 0 | Start | | |
# The last step degenerates to `GetNeighbors` when yield or filter properties other than `_dst`
When profiling query:
"""
GO 3 STEPS FROM "Tony Parker" OVER serve BIDIRECT WHERE $$.team.name != "Lakers" YIELD DISTINCT id($$) | YIELD count(*)
"""
Then the result should be, in any order, with relax comparison:
| count(*) |
| 21 |
And the execution plan should be:
| id | name | dependencies | operator info |
| 12 | Aggregate | 11 | |
| 11 | Project | 10 | |
| 10 | Filter | 9 | |
| 9 | LeftJoin | 8 | |
| 8 | Project | 7 | |
| 7 | GetVertices | 6 | |
| 6 | Dedup | 5 | |
| 5 | GetDstBySrc | 4 | |
| 4 | Loop | 0 | {"loopBody": "3"} |
| 3 | Dedup | 2 | |
| 2 | GetDstBySrc | 1 | |
| 1 | Start | | |
| 0 | Start | | |
# The last step degenerates to `GetNeighbors` when the yield clause is not `YIELD DISTINCT id($$)`
When profiling query:
"""
GO 3 STEPS FROM "Tony Parker" OVER serve BIDIRECT YIELD id($$) AS dst | YIELD count(*)
"""
Then the result should be, in any order, with relax comparison:
| count(*) |
| 65 |
And the execution plan should be:
| id | name | dependencies | operator info |
| 7 | Aggregate | 6 | |
| 6 | Project | 5 | |
| 5 | GetNeighbors | 4 | |
| 4 | Loop | 0 | {"loopBody": "3"} |
| 3 | Dedup | 2 | |
| 2 | GetDstBySrc | 1 | |
| 1 | Start | | |
| 0 | Start | | |
When profiling query:
"""
GO 3 STEPS FROM "Tony Parker" OVER serve BIDIRECT YIELD id($$) AS dst | YIELD count(*)
Expand All @@ -57,6 +96,24 @@ Feature: Simple case
| 2 | GetDstBySrc | 1 | |
| 1 | Start | | |
| 0 | Start | | |
When profiling query:
"""
GO 3 STEPS FROM "Tony Parker" OVER serve BIDIRECT WHERE $^.player.age > 30 YIELD DISTINCT id($$) AS dst | YIELD count(*)
"""
Then the result should be, in any order, with relax comparison:
| count(*) |
| 22 |
And the execution plan should be:
| id | name | dependencies | operator info |
| 9 | Aggregate | 8 | |
| 8 | Dedup | 7 | |
| 7 | Project | 10 | |
| 10 | GetNeighbors | 4 | |
| 4 | Loop | 0 | {"loopBody": "3"} |
| 3 | Dedup | 2 | |
| 2 | GetDstBySrc | 1 | |
| 1 | Start | | |
| 0 | Start | | |
When profiling query:
"""
GO 3 STEPS FROM "Tony Parker" OVER serve BIDIRECT YIELD $$.player.age AS age | YIELD count(*)
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