func addSelection(p Plan, child LogicalPlan, conditions []expression.Expression, allocator *idAllocator) error {
conditions = expression.PropagateConstant(p.context(), conditions)
selection := &Selection{
Conditions: conditions,
baseLogicalPlan: newBaseLogicalPlan(Sel, allocator)}
selection.self = selection
selection.initIDAndContext(p.context())
selection.SetSchema(child.GetSchema().Clone())
selection.correlated = child.IsCorrelated()
for _, cond := range conditions {
selection.correlated = selection.correlated || cond.IsCorrelated()
}
return InsertPlan(p, child, selection)
}
// PredicatePushDown implements LogicalPlan PredicatePushDown interface.
func (p *Selection) PredicatePushDown(predicates []expression.Expression) ([]expression.Expression, LogicalPlan, error) {
retConditions, child, err := p.GetChildByIndex(0).(LogicalPlan).PredicatePushDown(append(p.Conditions, predicates...))
if err != nil {
return nil, nil, errors.Trace(err)
}
if len(retConditions) > 0 {
p.Conditions = expression.PropagateConstant(p.ctx, retConditions)
return nil, p, nil
}
err = RemovePlan(p)
if err != nil {
return nil, nil, errors.Trace(err)
}
return nil, child, nil
}
func (s *testPlanSuite) TestConstantPropagation(c *C) {
defer testleak.AfterTest(c)()
cases := []struct {
sql string
after string
}{
{
sql: "a = b and b = c and c = d and d = 1",
after: "eq(test.t.a, 1), eq(test.t.b, 1), eq(test.t.c, 1), eq(test.t.d, 1)",
},
{
sql: "a = b and b = 1 and a = null and c = d and c > 2 and c != 4 and d != 5",
after: "0",
},
{
sql: "a = b and b = 1 and c = d and c > 2 and c != 4 and d != 5",
after: "eq(test.t.a, 1), eq(test.t.b, 1), eq(test.t.c, test.t.d), gt(test.t.c, 2), gt(test.t.d, 2), ne(test.t.c, 4), ne(test.t.c, 5), ne(test.t.d, 4), ne(test.t.d, 5)",
},
{
sql: "a = b and b > 0 and a = c",
after: "eq(test.t.a, test.t.b), eq(test.t.a, test.t.c), gt(test.t.a, 0), gt(test.t.b, 0), gt(test.t.c, 0)",
},
{
sql: "a = b and b = c and c LIKE 'abc%'",
after: "eq(test.t.a, test.t.b), eq(test.t.b, test.t.c), like(cast(test.t.c), abc%, 92)",
},
{
sql: "a = b and a > 2 and b > 3 and a < 1 and b < 2",
after: "eq(test.t.a, test.t.b), gt(test.t.a, 2), gt(test.t.a, 3), gt(test.t.b, 2), gt(test.t.b, 3), lt(test.t.a, 1), lt(test.t.a, 2), lt(test.t.b, 1), lt(test.t.b, 2)",
},
{
sql: "a = 1 and cast(null as SIGNED) is null",
after: "1, eq(test.t.a, 1)",
},
}
for _, ca := range cases {
sql := "select * from t where " + ca.sql
comment := Commentf("for %s", sql)
stmt, err := s.ParseOneStmt(sql, "", "")
c.Assert(err, IsNil, comment)
err = mockResolve(stmt)
c.Assert(err, IsNil)
builder := &planBuilder{
allocator: new(idAllocator),
ctx: mock.NewContext(),
colMapper: make(map[*ast.ColumnNameExpr]int),
}
p := builder.build(stmt)
c.Assert(builder.err, IsNil)
lp := p.(LogicalPlan)
var (
sel *Selection
ok bool
result []string
)
v := lp
for {
if sel, ok = v.(*Selection); ok {
break
}
v = v.GetChildByIndex(0).(LogicalPlan)
}
newConds := expression.PropagateConstant(builder.ctx, sel.Conditions)
for _, v := range newConds {
result = append(result, v.String())
}
sort.Strings(result)
c.Assert(strings.Join(result, ", "), Equals, ca.after, Commentf("for %s", ca.sql))
}
}
// PredicatePushDown implements LogicalPlan PredicatePushDown interface.
func (p *Join) PredicatePushDown(predicates []expression.Expression) (ret []expression.Expression, retPlan LogicalPlan, err error) {
err = outerJoinSimplify(p, predicates)
if err != nil {
return nil, nil, errors.Trace(err)
}
groups, valid := tryToGetJoinGroup(p)
if valid {
e := joinReOrderSolver{allocator: p.allocator}
e.reorderJoin(groups, predicates)
newJoin := e.resultJoin
parent := p.parents[0]
newJoin.SetParents(parent)
parent.ReplaceChild(p, newJoin)
return newJoin.PredicatePushDown(predicates)
}
var leftCond, rightCond []expression.Expression
retPlan = p
leftPlan := p.GetChildByIndex(0).(LogicalPlan)
rightPlan := p.GetChildByIndex(1).(LogicalPlan)
var (
equalCond []*expression.ScalarFunction
leftPushCond, rightPushCond, otherCond []expression.Expression
)
if p.JoinType != InnerJoin {
equalCond, leftPushCond, rightPushCond, otherCond = extractOnCondition(predicates, leftPlan, rightPlan)
} else {
tempCond := make([]expression.Expression, 0, len(p.LeftConditions)+len(p.RightConditions)+len(p.EqualConditions)+len(p.OtherConditions)+len(predicates))
tempCond = append(tempCond, p.LeftConditions...)
tempCond = append(tempCond, p.RightConditions...)
tempCond = append(tempCond, expression.ScalarFuncs2Exprs(p.EqualConditions)...)
tempCond = append(tempCond, p.OtherConditions...)
tempCond = append(tempCond, predicates...)
equalCond, leftPushCond, rightPushCond, otherCond = extractOnCondition(expression.PropagateConstant(p.ctx, tempCond), leftPlan, rightPlan)
}
switch p.JoinType {
case LeftOuterJoin, SemiJoinWithAux:
rightCond = p.RightConditions
p.RightConditions = nil
leftCond = leftPushCond
ret = append(expression.ScalarFuncs2Exprs(equalCond), otherCond...)
ret = append(ret, rightPushCond...)
case RightOuterJoin:
leftCond = p.LeftConditions
p.LeftConditions = nil
rightCond = rightPushCond
ret = append(expression.ScalarFuncs2Exprs(equalCond), otherCond...)
ret = append(ret, leftPushCond...)
case SemiJoin:
equalCond, leftPushCond, rightPushCond, otherCond = extractOnCondition(predicates, leftPlan, rightPlan)
leftCond = append(p.LeftConditions, leftPushCond...)
rightCond = append(p.RightConditions, rightPushCond...)
p.LeftConditions = nil
p.RightConditions = nil
case InnerJoin:
p.LeftConditions = nil
p.RightConditions = nil
p.EqualConditions = equalCond
p.OtherConditions = otherCond
leftCond = leftPushCond
rightCond = rightPushCond
}
leftRet, _, err1 := leftPlan.PredicatePushDown(leftCond)
if err1 != nil {
return nil, nil, errors.Trace(err1)
}
rightRet, _, err2 := rightPlan.PredicatePushDown(rightCond)
if err2 != nil {
return nil, nil, errors.Trace(err2)
}
if len(leftRet) > 0 {
err2 = addSelection(p, leftPlan, leftRet, p.allocator)
if err2 != nil {
return nil, nil, errors.Trace(err2)
}
}
if len(rightRet) > 0 {
err2 = addSelection(p, rightPlan, rightRet, p.allocator)
if err2 != nil {
return nil, nil, errors.Trace(err2)
}
}
return
}
