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planner: refine tryToGetIndexJoin #45587

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Merged
merged 6 commits into from
Jul 26, 2023
Merged

planner: refine tryToGetIndexJoin #45587

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9301980
fixup
qw4990 Jul 26, 2023
79653d3
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qw4990 Jul 26, 2023
34eaa48
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qw4990 Jul 26, 2023
b9e2c48
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qw4990 Jul 26, 2023
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qw4990 Jul 26, 2023
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qw4990 Jul 26, 2023
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119 changes: 56 additions & 63 deletions planner/core/exhaust_physical_plans.go
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Original file line number Diff line number Diff line change
Expand Up @@ -1969,61 +1969,75 @@ func filterIndexJoinBySessionVars(sc sessionctx.Context, indexJoins []PhysicalPl
return indexJoins
}

func (p *LogicalJoin) prefer(joinFlags ...uint) bool {
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Suggest renaming it like preferAny to make it more clear.

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updated

for _, flag := range joinFlags {
if p.preferJoinType&flag > 0 {
return true
}
}
return false
}

// canPassJoinHint returns whether this join plan can pass current join hints.
func (p *LogicalJoin) canPassJoinHint(join PhysicalPlan, leftOuter bool) bool {
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Suggest renaming it like indexJoinSatisfiesHint because the actual logic assumes join is an index join.

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We can also use (*basePhysicalJoin).getInnerChildIdx() to avoid the need to pass the leftOuter.

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Good suggestion, updated.

const left, right = 0, 1
const indexJoin, indexHashJoin, indexMergeJoin = 0, 1, 2
innerSide := left
if leftOuter {
innerSide = right
}
joinMethod := indexJoin
switch join.(type) {
case *PhysicalIndexHashJoin:
joinMethod = indexHashJoin
case *PhysicalIndexMergeJoin:
joinMethod = indexMergeJoin
}

if (p.prefer(preferLeftAsINLJInner) && innerSide == left && joinMethod == indexJoin) ||
(p.prefer(preferRightAsINLJInner) && innerSide == right && joinMethod == indexJoin) ||
(p.prefer(preferLeftAsINLHJInner) && innerSide == left && joinMethod == indexHashJoin) ||
(p.prefer(preferRightAsINLHJInner) && innerSide == right && joinMethod == indexHashJoin) ||
(p.prefer(preferLeftAsINLMJInner) && innerSide == left && joinMethod == indexMergeJoin) ||
(p.prefer(preferRightAsINLMJInner) && innerSide == right && joinMethod == indexMergeJoin) {
return true
}
return false
}

// tryToGetIndexJoin will get index join by hints. If we can generate a valid index join by hint, the second return value
// will be true, which means we force to choose this index join. Otherwise we will select a join algorithm with min-cost.
func (p *LogicalJoin) tryToGetIndexJoin(prop *property.PhysicalProperty) (indexJoins []PhysicalPlan, canForced bool) {
inljRightOuter := (p.preferJoinType & preferLeftAsINLJInner) > 0
inljLeftOuter := (p.preferJoinType & preferRightAsINLJInner) > 0
hasINLJHint := inljLeftOuter || inljRightOuter

inlhjRightOuter := (p.preferJoinType & preferLeftAsINLHJInner) > 0
inlhjLeftOuter := (p.preferJoinType & preferRightAsINLHJInner) > 0
hasINLHJHint := inlhjLeftOuter || inlhjRightOuter

inlmjRightOuter := (p.preferJoinType & preferLeftAsINLMJInner) > 0
inlmjLeftOuter := (p.preferJoinType & preferRightAsINLMJInner) > 0
hasINLMJHint := inlmjLeftOuter || inlmjRightOuter

forceLeftOuter := inljLeftOuter || inlhjLeftOuter || inlmjLeftOuter
forceRightOuter := inljRightOuter || inlhjRightOuter || inlmjRightOuter
forceLeftOuter := p.prefer(preferRightAsINLJInner, preferRightAsINLHJInner, preferRightAsINLMJInner) // left as outer == right as inner
forceRightOuter := p.prefer(preferLeftAsINLJInner, preferLeftAsINLHJInner, preferLeftAsINLMJInner) // right as outer == left as inner
needForced := forceLeftOuter || forceRightOuter

defer func() {
// refine error message
// Print warning message if any hints cannot work.
// If the required property is not empty, we will enforce it and try the hint again.
// So we only need to generate warning message when the property is empty.
if !canForced && needForced && prop.IsSortItemEmpty() {
// Construct warning message prefix.
var indexJoinTables, indexHashJoinTables, indexMergeJoinTables []hintTableInfo
if p.hintInfo != nil {
t := p.hintInfo.indexNestedLoopJoinTables
indexJoinTables, indexHashJoinTables, indexMergeJoinTables = t.inljTables, t.inlhjTables, t.inlmjTables
}
var errMsg string
switch {
case hasINLJHint:
errMsg = "Optimizer Hint INL_JOIN or TIDB_INLJ is inapplicable"
case hasINLHJHint:
errMsg = "Optimizer Hint INL_HASH_JOIN is inapplicable"
case hasINLMJHint:
errMsg = "Optimizer Hint INL_MERGE_JOIN is inapplicable"
}
if p.hintInfo != nil && p.preferJoinType > 0 {
t := p.hintInfo.indexNestedLoopJoinTables
switch {
case len(t.inljTables) != 0 && ((p.preferJoinType&preferLeftAsINLJInner > 0) || (p.preferJoinType&preferRightAsINLJInner > 0)):
errMsg = fmt.Sprintf("Optimizer Hint %s or %s is inapplicable",
restore2JoinHint(HintINLJ, t.inljTables), restore2JoinHint(TiDBIndexNestedLoopJoin, t.inljTables))
case len(t.inlhjTables) != 0 && ((p.preferJoinType&preferLeftAsINLHJInner > 0) || (p.preferJoinType&preferRightAsINLHJInner > 0)):
errMsg = fmt.Sprintf("Optimizer Hint %s is inapplicable", restore2JoinHint(HintINLHJ, t.inlhjTables))
case len(t.inlmjTables) != 0 && ((p.preferJoinType&preferLeftAsINLMJInner > 0) || (p.preferJoinType&preferRightAsINLMJInner > 0)):
errMsg = fmt.Sprintf("Optimizer Hint %s is inapplicable", restore2JoinHint(HintINLMJ, t.inlmjTables))
}
case p.prefer(preferLeftAsINLJInner, preferRightAsINLJInner): // prefer index join
errMsg = fmt.Sprintf("Optimizer Hint %s or %s is inapplicable", restore2JoinHint(HintINLJ, indexJoinTables), restore2JoinHint(TiDBIndexNestedLoopJoin, indexJoinTables))
case p.prefer(preferLeftAsINLHJInner, preferRightAsINLHJInner): // prefer index hash join
errMsg = fmt.Sprintf("Optimizer Hint %s is inapplicable", restore2JoinHint(HintINLHJ, indexHashJoinTables))
case p.prefer(preferLeftAsINLMJInner, preferRightAsINLMJInner): // prefer index merge join
errMsg = fmt.Sprintf("Optimizer Hint %s is inapplicable", restore2JoinHint(HintINLMJ, indexMergeJoinTables))
}

// Append inapplicable reason.
if len(p.EqualConditions) == 0 {
errMsg += " without column equal ON condition"
}

// Generate warning message to client.
warning := ErrInternal.GenWithStack(errMsg)
p.SCtx().GetSessionVars().StmtCtx.AppendWarning(warning)
p.SCtx().GetSessionVars().StmtCtx.AppendWarning(ErrInternal.GenWithStack(errMsg))
}
}()

Expand All @@ -2044,19 +2058,8 @@ func (p *LogicalJoin) tryToGetIndexJoin(prop *property.PhysicalProperty) (indexJ
allLeftOuterJoins = p.getIndexJoinByOuterIdx(prop, 0)
forcedLeftOuterJoins = make([]PhysicalPlan, 0, len(allLeftOuterJoins))
for _, j := range allLeftOuterJoins {
switch j.(type) {
case *PhysicalIndexJoin:
if inljLeftOuter {
forcedLeftOuterJoins = append(forcedLeftOuterJoins, j)
}
case *PhysicalIndexHashJoin:
if inlhjLeftOuter {
forcedLeftOuterJoins = append(forcedLeftOuterJoins, j)
}
case *PhysicalIndexMergeJoin:
if inlmjLeftOuter {
forcedLeftOuterJoins = append(forcedLeftOuterJoins, j)
}
if p.canPassJoinHint(j, true) {
forcedLeftOuterJoins = append(forcedLeftOuterJoins, j)
}
}
switch {
Expand All @@ -2066,23 +2069,13 @@ func (p *LogicalJoin) tryToGetIndexJoin(prop *property.PhysicalProperty) (indexJ
return forcedLeftOuterJoins, true
}
}

if supportRightOuter {
allRightOuterJoins = p.getIndexJoinByOuterIdx(prop, 1)
forcedRightOuterJoins = make([]PhysicalPlan, 0, len(allRightOuterJoins))
for _, j := range allRightOuterJoins {
switch j.(type) {
case *PhysicalIndexJoin:
if inljRightOuter {
forcedRightOuterJoins = append(forcedRightOuterJoins, j)
}
case *PhysicalIndexHashJoin:
if inlhjRightOuter {
forcedRightOuterJoins = append(forcedRightOuterJoins, j)
}
case *PhysicalIndexMergeJoin:
if inlmjRightOuter {
forcedRightOuterJoins = append(forcedRightOuterJoins, j)
}
if p.canPassJoinHint(j, false) {
forcedRightOuterJoins = append(forcedRightOuterJoins, j)
}
}
switch {
Expand Down
3 changes: 3 additions & 0 deletions planner/core/planbuilder.go
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Original file line number Diff line number Diff line change
Expand Up @@ -343,6 +343,9 @@ func restore2TableHint(hintTables ...hintTableInfo) string {
}

func restore2JoinHint(hintType string, hintTables []hintTableInfo) string {
if len(hintTables) == 0 {
return strings.ToUpper(hintType)
}
buffer := bytes.NewBufferString("/*+ ")
buffer.WriteString(strings.ToUpper(hintType))
buffer.WriteString("(")
Expand Down