71 lines
2.6 KiB
Go
71 lines
2.6 KiB
Go
// Copyright 2024 PingCAP, Inc.
|
|
//
|
|
// Licensed under the Apache License, Version 2.0 (the "License");
|
|
// you may not use this file except in compliance with the License.
|
|
// You may obtain a copy of the License at
|
|
//
|
|
// http://www.apache.org/licenses/LICENSE-2.0
|
|
//
|
|
// Unless required by applicable law or agreed to in writing, software
|
|
// distributed under the License is distributed on an "AS IS" BASIS,
|
|
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
|
|
// See the License for the specific language governing permissions and
|
|
// limitations under the License.
|
|
|
|
package constraint
|
|
|
|
import (
|
|
"slices"
|
|
|
|
"github.com/pingcap/tidb/pkg/expression"
|
|
"github.com/pingcap/tidb/pkg/parser/ast"
|
|
"github.com/pingcap/tidb/pkg/parser/mysql"
|
|
"github.com/pingcap/tidb/pkg/sessionctx/stmtctx"
|
|
)
|
|
|
|
// DeleteTrueExprs deletes the surely true expressions
|
|
func DeleteTrueExprs(buildCtx expression.BuildContext, stmtCtx *stmtctx.StatementContext, conds []expression.Expression) []expression.Expression {
|
|
if len(conds) == 0 {
|
|
return conds
|
|
}
|
|
return slices.DeleteFunc(conds, func(cond expression.Expression) bool {
|
|
con, ok := cond.(*expression.Constant)
|
|
if !ok {
|
|
return false
|
|
}
|
|
if expression.MaybeOverOptimized4PlanCache(buildCtx, con) {
|
|
return false
|
|
}
|
|
isTrue, err := con.Value.ToBool(stmtCtx.TypeCtx())
|
|
return err == nil && isTrue == 1
|
|
})
|
|
}
|
|
|
|
// DeleteTrueExprsBySchema delete true expressions such as not(isnull(not null column)).
|
|
// It is used in the predicate pushdown optimization to remove unnecessary conditions which will be pushed down to child operators.
|
|
func DeleteTrueExprsBySchema(ctx expression.EvalContext, schema *expression.Schema, conds []expression.Expression) []expression.Expression {
|
|
return slices.DeleteFunc(conds, func(item expression.Expression) bool {
|
|
if expr, ok := item.(*expression.ScalarFunction); ok && expr.FuncName.L == ast.UnaryNot {
|
|
if args := expr.GetArgs(); len(args) == 1 {
|
|
// If the expression is `not(isnull(not null column))`, we can remove it.
|
|
return isNullWithNotNullColumn(ctx, schema, args[0])
|
|
}
|
|
}
|
|
return false
|
|
})
|
|
}
|
|
|
|
// isNullWithNotNullColumn checks if the expression is `isnull(not null column)`.
|
|
func isNullWithNotNullColumn(ctx expression.EvalContext, schema *expression.Schema, expr expression.Expression) bool {
|
|
if e, ok := expr.(*expression.ScalarFunction); ok && e.FuncName.L == ast.IsNull {
|
|
if args := e.GetArgs(); len(args) == 1 {
|
|
if col, ok := args[0].(*expression.Column); ok {
|
|
if retrieveColumn := schema.RetrieveColumn(col); retrieveColumn != nil {
|
|
return mysql.HasNotNullFlag(retrieveColumn.GetType(ctx).GetFlag())
|
|
}
|
|
}
|
|
}
|
|
}
|
|
return false
|
|
}
|