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*: refactor limit hint #50730

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merged 1 commit into from
Jan 25, 2024
Merged

*: refactor limit hint #50730

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4 changes: 2 additions & 2 deletions pkg/planner/core/exhaust_physical_plans.go
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Original file line number Diff line number Diff line change
Expand Up @@ -2679,10 +2679,10 @@ func pushLimitOrTopNForcibly(p LogicalPlan) bool {
var preferPushDown *bool
switch lp := p.(type) {
case *LogicalTopN:
preferPushDown = &lp.limitHints.PreferLimitToCop
preferPushDown = &lp.PreferLimitToCop
meetThreshold = lp.Count+lp.Offset <= uint64(lp.SCtx().GetSessionVars().LimitPushDownThreshold)
case *LogicalLimit:
preferPushDown = &lp.limitHints.PreferLimitToCop
preferPushDown = &lp.PreferLimitToCop
meetThreshold = true // always push Limit down in this case since it has no side effect
default:
return false
Expand Down
8 changes: 4 additions & 4 deletions pkg/planner/core/logical_plan_builder.go
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Original file line number Diff line number Diff line change
Expand Up @@ -2435,7 +2435,7 @@ func (b *PlanBuilder) buildLimit(src LogicalPlan, limit *ast.Limit) (LogicalPlan
Count: count,
}.Init(b.ctx, b.getSelectOffset())
if hint := b.TableHints(); hint != nil {
li.limitHints = hint.Limit
li.PreferLimitToCop = hint.PreferLimitToCop
}
li.SetChildren(src)
return li, nil
Expand Down Expand Up @@ -3966,7 +3966,7 @@ func (b *PlanBuilder) pushTableHints(hints []*ast.TableOptimizerHint, currentLev
tiflashTables, tikvTables []h.HintedTable
aggHints h.AggHints
timeRangeHint ast.HintTimeRange
limitHints h.LimitHints
preferLimitToCop bool
cteMerge bool
leadingJoinOrder []h.HintedTable
hjBuildTables, hjProbeTables []h.HintedTable
Expand Down Expand Up @@ -4076,7 +4076,7 @@ func (b *PlanBuilder) pushTableHints(hints []*ast.TableOptimizerHint, currentLev
case h.HintTimeRange:
timeRangeHint = hint.HintData.(ast.HintTimeRange)
case h.HintLimitToCop:
limitHints.PreferLimitToCop = true
preferLimitToCop = true
case h.HintMerge:
if hint.Tables != nil {
b.ctx.GetSessionVars().StmtCtx.SetHintWarning(ErrInternal.FastGen("The MERGE hint is not used correctly, maybe it inputs a table name."))
Expand Down Expand Up @@ -4128,7 +4128,7 @@ func (b *PlanBuilder) pushTableHints(hints []*ast.TableOptimizerHint, currentLev
Agg: aggHints,
IndexMergeHintList: indexMergeHintList,
TimeRangeHint: timeRangeHint,
Limit: limitHints,
PreferLimitToCop: preferLimitToCop,
CTEMerge: cteMerge,
LeadingJoinOrder: leadingJoinOrder,
HJBuild: hjBuildTables,
Expand Down
18 changes: 9 additions & 9 deletions pkg/planner/core/logical_plans.go
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Expand Up @@ -1917,10 +1917,10 @@ type LogicalTopN struct {

ByItems []*util.ByItems
// PartitionBy is used for extended TopN to consider K heaps. Used by rule_derive_topn_from_window
PartitionBy []property.SortItem // This is used for enhanced topN optimization
Offset uint64
Count uint64
limitHints h.LimitHints
PartitionBy []property.SortItem // This is used for enhanced topN optimization
Offset uint64
Count uint64
PreferLimitToCop bool
}

// GetPartitionBy returns partition by fields
Expand All @@ -1946,11 +1946,11 @@ func (lt *LogicalTopN) isLimit() bool {
type LogicalLimit struct {
logicalSchemaProducer

PartitionBy []property.SortItem // This is used for enhanced topN optimization
Offset uint64
Count uint64
limitHints h.LimitHints
IsPartial bool
PartitionBy []property.SortItem // This is used for enhanced topN optimization
Offset uint64
Count uint64
PreferLimitToCop bool
IsPartial bool
}

// GetPartitionBy returns partition by fields
Expand Down
18 changes: 9 additions & 9 deletions pkg/planner/core/rule_topn_push_down.go
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Expand Up @@ -66,10 +66,10 @@ func (lt *LogicalTopN) setChild(p LogicalPlan, opt *logicalOptimizeOp) LogicalPl

if lt.isLimit() {
limit := LogicalLimit{
Count: lt.Count,
Offset: lt.Offset,
limitHints: lt.limitHints,
PartitionBy: lt.GetPartitionBy(),
Count: lt.Count,
Offset: lt.Offset,
PreferLimitToCop: lt.PreferLimitToCop,
PartitionBy: lt.GetPartitionBy(),
}.Init(lt.SCtx(), lt.QueryBlockOffset())
limit.SetChildren(p)
appendTopNPushDownTraceStep(limit, p, opt)
Expand All @@ -94,7 +94,7 @@ func (ls *LogicalSort) pushDownTopN(topN *LogicalTopN, opt *logicalOptimizeOp) L
}

func (p *LogicalLimit) convertToTopN(opt *logicalOptimizeOp) *LogicalTopN {
topn := LogicalTopN{Offset: p.Offset, Count: p.Count, limitHints: p.limitHints}.Init(p.SCtx(), p.QueryBlockOffset())
topn := LogicalTopN{Offset: p.Offset, Count: p.Count, PreferLimitToCop: p.PreferLimitToCop}.Init(p.SCtx(), p.QueryBlockOffset())
appendConvertTopNTraceStep(p, topn, opt)
return topn
}
Expand All @@ -111,7 +111,7 @@ func (p *LogicalUnionAll) pushDownTopN(topN *LogicalTopN, opt *logicalOptimizeOp
for i, child := range p.children {
var newTopN *LogicalTopN
if topN != nil {
newTopN = LogicalTopN{Count: topN.Count + topN.Offset, limitHints: topN.limitHints}.Init(p.SCtx(), topN.QueryBlockOffset())
newTopN = LogicalTopN{Count: topN.Count + topN.Offset, PreferLimitToCop: topN.PreferLimitToCop}.Init(p.SCtx(), topN.QueryBlockOffset())
for _, by := range topN.ByItems {
newTopN.ByItems = append(newTopN.ByItems, &util.ByItems{Expr: by.Expr, Desc: by.Desc})
}
Expand Down Expand Up @@ -187,9 +187,9 @@ func (p *LogicalJoin) pushDownTopNToChild(topN *LogicalTopN, idx int, opt *logic
}

newTopN := LogicalTopN{
Count: topN.Count + topN.Offset,
ByItems: make([]*util.ByItems, len(topN.ByItems)),
limitHints: topN.limitHints,
Count: topN.Count + topN.Offset,
ByItems: make([]*util.ByItems, len(topN.ByItems)),
PreferLimitToCop: topN.PreferLimitToCop,
}.Init(topN.SCtx(), topN.QueryBlockOffset())
for i := range topN.ByItems {
newTopN.ByItems[i] = topN.ByItems[i].Clone()
Expand Down
13 changes: 4 additions & 9 deletions pkg/util/hint/hint.go
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Expand Up @@ -229,15 +229,10 @@ type PlanHints struct {
HJProbe []HintedTable // hash_join_probe

// Hints belows are not associated with any particular table.
Agg AggHints // hash_agg, merge_agg, agg_to_cop
Limit LimitHints // limit_to_cop
CTEMerge bool // merge
TimeRangeHint ast.HintTimeRange
}

// LimitHints stores limit hint information.
type LimitHints struct {
PreferLimitToCop bool
Agg AggHints // hash_agg, merge_agg, agg_to_cop
PreferLimitToCop bool // limit_to_cop
CTEMerge bool // merge
TimeRangeHint ast.HintTimeRange
}

// HintedTable indicates which table this hint should take effect on.
Expand Down