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expression, planner: push cast down to control function with enum typ…
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…e. (#24542)
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@wshwsh12
wshwsh12 authored May 18, 2021
1 parent 3ec8c8b commit ac7e6a4
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90 changes: 90 additions & 0 deletions expression/builtin_cast.go
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Original file line number Diff line number Diff line change
Expand Up @@ -1804,6 +1804,7 @@ func BuildCastFunction4Union(ctx sessionctx.Context, expr Expression, tp *types.

// BuildCastFunction builds a CAST ScalarFunction from the Expression.
func BuildCastFunction(ctx sessionctx.Context, expr Expression, tp *types.FieldType) (res Expression) {
expr = TryPushCastIntoControlFunctionForHybridType(ctx, expr, tp)
var fc functionClass
switch tp.EvalType() {
case types.ETInt:
Expand Down Expand Up @@ -1983,3 +1984,92 @@ func WrapWithCastAsJSON(ctx sessionctx.Context, expr Expression) Expression {
}
return BuildCastFunction(ctx, expr, tp)
}

// TryPushCastIntoControlFunctionForHybridType try to push cast into control function for Hybrid Type.
// If necessary, it will rebuild control function using changed args.
// When a hybrid type is the output of a control function, the result may be as a numeric type to subsequent calculation
// We should perform the `Cast` operation early to avoid using the wrong type for calculation
// For example, the condition `if(1, e, 'a') = 1`, `if` function will output `e` and compare with `1`.
// If the evaltype is ETString, it will get wrong result. So we can rewrite the condition to
// `IfInt(1, cast(e as int), cast('a' as int)) = 1` to get the correct result.
func TryPushCastIntoControlFunctionForHybridType(ctx sessionctx.Context, expr Expression, tp *types.FieldType) (res Expression) {
sf, ok := expr.(*ScalarFunction)
if !ok {
return expr
}

var wrapCastFunc func(ctx sessionctx.Context, expr Expression) Expression
switch tp.EvalType() {
case types.ETInt:
wrapCastFunc = WrapWithCastAsInt
case types.ETReal:
wrapCastFunc = WrapWithCastAsReal
default:
return expr
}

isHybrid := func(ft *types.FieldType) bool {
// todo: compatible with mysql control function using bit type. issue 24725
return ft.Hybrid() && ft.Tp != mysql.TypeBit
}

args := sf.GetArgs()
switch sf.FuncName.L {
case ast.If:
if isHybrid(args[1].GetType()) || isHybrid(args[2].GetType()) {
args[1] = wrapCastFunc(ctx, args[1])
args[2] = wrapCastFunc(ctx, args[2])
f, err := funcs[ast.If].getFunction(ctx, args)
if err != nil {
return expr
}
sf.RetType, sf.Function = f.getRetTp(), f
return sf
}
case ast.Case:
hasHybrid := false
for i := 0; i < len(args)-1; i += 2 {
hasHybrid = hasHybrid || isHybrid(args[i+1].GetType())
}
if len(args)%2 == 1 {
hasHybrid = hasHybrid || isHybrid(args[len(args)-1].GetType())
}
if !hasHybrid {
return expr
}

for i := 0; i < len(args)-1; i += 2 {
args[i+1] = wrapCastFunc(ctx, args[i+1])
}
if len(args)%2 == 1 {
args[len(args)-1] = wrapCastFunc(ctx, args[len(args)-1])
}
f, err := funcs[ast.Case].getFunction(ctx, args)
if err != nil {
return expr
}
sf.RetType, sf.Function = f.getRetTp(), f
return sf
case ast.Elt:
hasHybrid := false
for i := 1; i < len(args); i++ {
hasHybrid = hasHybrid || isHybrid(args[i].GetType())
}
if !hasHybrid {
return expr
}

for i := 1; i < len(args); i++ {
args[i] = wrapCastFunc(ctx, args[i])
}
f, err := funcs[ast.Elt].getFunction(ctx, args)
if err != nil {
return expr
}
sf.RetType, sf.Function = f.getRetTp(), f
return sf
default:
return expr
}
return expr
}
73 changes: 73 additions & 0 deletions expression/integration_test.go
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Original file line number Diff line number Diff line change
Expand Up @@ -9435,3 +9435,76 @@ func (s *testIntegrationSuite) TestEnumIndex(c *C) {
tk.MustQuery("select /*+ use_index(t,idx) */ col3 from t where col2 = 'b' and col1 is not null;").Check(
testkit.Rows("2"))
}

func (s *testIntegrationSuite) TestControlFunctionWithEnumOrSet(c *C) {
defer s.cleanEnv(c)

// issue 23114
tk := testkit.NewTestKit(c, s.store)
tk.MustExec("use test")
tk.MustExec("drop table if exists e;")
tk.MustExec("create table e(e enum('c', 'b', 'a'));")
tk.MustExec("insert into e values ('a'),('b'),('a'),('b');")
tk.MustQuery("select e from e where if(e>1, e, e);").Sort().Check(
testkit.Rows("a", "a", "b", "b"))
tk.MustQuery("select e from e where case e when 1 then e else e end;").Sort().Check(
testkit.Rows("a", "a", "b", "b"))
tk.MustQuery("select e from e where case 1 when e then e end;").Check(testkit.Rows())

tk.MustQuery("select if(e>1,e,e)='a' from e").Sort().Check(
testkit.Rows("0", "0", "1", "1"))
tk.MustQuery("select if(e>1,e,e)=1 from e").Sort().Check(
testkit.Rows("0", "0", "0", "0"))
// if and if
tk.MustQuery("select if(e>2,e,e) and if(e<=2,e,e) from e;").Sort().Check(
testkit.Rows("1", "1", "1", "1"))
tk.MustQuery("select if(e>2,e,e) and (if(e<3,0,e) or if(e>=2,0,e)) from e;").Sort().Check(
testkit.Rows("0", "0", "1", "1"))
tk.MustQuery("select * from e where if(e>2,e,e) and if(e<=2,e,e);").Sort().Check(
testkit.Rows("a", "a", "b", "b"))
tk.MustQuery("select * from e where if(e>2,e,e) and (if(e<3,0,e) or if(e>=2,0,e));").Sort().Check(
testkit.Rows("a", "a"))

// issue 24494
tk.MustExec("drop table if exists t;")
tk.MustExec("create table t(a int,b enum(\"b\",\"y\",\"1\"));")
tk.MustExec("insert into t values(0,\"y\"),(1,\"b\"),(null,null),(2,\"1\");")
tk.MustQuery("SELECT count(*) FROM t where if(a,b ,null);").Check(testkit.Rows("2"))

tk.MustExec("drop table if exists t;")
tk.MustExec("create table t(a int,b enum(\"b\"),c enum(\"c\"));")
tk.MustExec("insert into t values(1,1,1),(2,1,1),(1,1,1),(2,1,1);")
tk.MustQuery("select a from t where if(a=1,b,c)=\"b\";").Check(testkit.Rows("1", "1"))
tk.MustQuery("select a from t where if(a=1,b,c)=\"c\";").Check(testkit.Rows("2", "2"))
tk.MustQuery("select a from t where if(a=1,b,c)=1;").Sort().Check(testkit.Rows("1", "1", "2", "2"))
tk.MustQuery("select a from t where if(a=1,b,c);").Sort().Check(testkit.Rows("1", "1", "2", "2"))

tk.MustExec("drop table if exists e;")
tk.MustExec("create table e(e enum('c', 'b', 'a'));")
tk.MustExec("insert into e values(3)")
tk.MustQuery("select elt(1,e) = 'a' from e").Check(testkit.Rows("1"))
tk.MustQuery("select elt(1,e) = 3 from e").Check(testkit.Rows("1"))
tk.MustQuery("select e from e where elt(1,e)").Check(testkit.Rows("a"))

// test set type
tk.MustExec("drop table if exists s;")
tk.MustExec("create table s(s set('c', 'b', 'a'));")
tk.MustExec("insert into s values ('a'),('b'),('a'),('b');")
tk.MustQuery("select s from s where if(s>1, s, s);").Sort().Check(
testkit.Rows("a", "a", "b", "b"))
tk.MustQuery("select s from s where case s when 1 then s else s end;").Sort().Check(
testkit.Rows("a", "a", "b", "b"))
tk.MustQuery("select s from s where case 1 when s then s end;").Check(testkit.Rows())

tk.MustQuery("select if(s>1,s,s)='a' from s").Sort().Check(
testkit.Rows("0", "0", "1", "1"))
tk.MustQuery("select if(s>1,s,s)=4 from s").Sort().Check(
testkit.Rows("0", "0", "1", "1"))

tk.MustExec("drop table if exists s;")
tk.MustExec("create table s(s set('c', 'b', 'a'));")
tk.MustExec("insert into s values('a')")
tk.MustQuery("select elt(1,s) = 'a' from s").Check(testkit.Rows("1"))
tk.MustQuery("select elt(1,s) = 4 from s").Check(testkit.Rows("1"))
tk.MustQuery("select s from s where elt(1,s)").Check(testkit.Rows("a"))
}
13 changes: 13 additions & 0 deletions planner/core/logical_plan_builder.go
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Original file line number Diff line number Diff line change
Expand Up @@ -975,6 +975,19 @@ func (b *PlanBuilder) buildSelection(ctx context.Context, p LogicalPlan, where a
if len(cnfExpres) == 0 {
return p, nil
}
// check expr field types.
for i, expr := range cnfExpres {
if expr.GetType().EvalType() == types.ETString {
tp := &types.FieldType{
Tp: mysql.TypeDouble,
Flag: expr.GetType().Flag,
Flen: mysql.MaxRealWidth,
Decimal: types.UnspecifiedLength,
}
types.SetBinChsClnFlag(tp)
cnfExpres[i] = expression.TryPushCastIntoControlFunctionForHybridType(b.ctx, expr, tp)
}
}
selection.Conditions = cnfExpres
selection.SetChildren(p)
return selection, nil
Expand Down

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