expression: introduce cast(... as ... array) in expression index

br/pkg/lightning/backend/kv/sql2kv.go

@@ -169,7 +169,7 @@ func collectGeneratedColumns(se *session, meta *model.TableInfo, cols []*table.C
 	var genCols []genCol
 	for i, col := range cols {
 		if col.GeneratedExpr != nil {
-			expr, err := expression.RewriteAstExpr(se, col.GeneratedExpr, schema, names)
+			expr, err := expression.RewriteAstExpr(se, col.GeneratedExpr, schema, names, false)
 			if err != nil {
 				return nil, err
 			}

ddl/ddl_api.go

@@ -6164,7 +6164,7 @@ func (d *ddl) CreatePrimaryKey(ctx sessionctx.Context, ti ast.Ident, indexName m
 	// After DDL job is put to the queue, and if the check fail, TiDB will run the DDL cancel logic.
 	// The recover step causes DDL wait a few seconds, makes the unit test painfully slow.
 	// For same reason, decide whether index is global here.
-	indexColumns, err := buildIndexColumns(ctx, tblInfo.Columns, indexPartSpecifications)
+	indexColumns, _, err := buildIndexColumns(ctx, tblInfo.Columns, indexPartSpecifications)
 	if err != nil {
 		return errors.Trace(err)
 	}
@@ -6274,7 +6274,7 @@ func BuildHiddenColumnInfo(ctx sessionctx.Context, indexPartSpecifications []*as
 		if err != nil {
 			return nil, errors.Trace(err)
 		}
-		expr, err := expression.RewriteSimpleExprWithTableInfo(ctx, tblInfo, idxPart.Expr)
+		expr, err := expression.RewriteSimpleExprWithTableInfo(ctx, tblInfo, idxPart.Expr, true)
 		if err != nil {
 			// TODO: refine the error message.
 			return nil, err
@@ -6389,7 +6389,7 @@ func (d *ddl) createIndex(ctx sessionctx.Context, ti ast.Ident, keyType ast.Inde
 	// After DDL job is put to the queue, and if the check fail, TiDB will run the DDL cancel logic.
 	// The recover step causes DDL wait a few seconds, makes the unit test painfully slow.
 	// For same reason, decide whether index is global here.
-	indexColumns, err := buildIndexColumns(ctx, finalColumns, indexPartSpecifications)
+	indexColumns, _, err := buildIndexColumns(ctx, finalColumns, indexPartSpecifications)
 	if err != nil {
 		return errors.Trace(err)
 	}

ddl/generated_column.go

@@ -268,12 +268,14 @@ func checkModifyGeneratedColumn(sctx sessionctx.Context, tbl table.Table, oldCol
 }
 
 type illegalFunctionChecker struct {
-	hasIllegalFunc       bool
-	hasAggFunc           bool
-	hasRowVal            bool // hasRowVal checks whether the functional index refers to a row value
-	hasWindowFunc        bool
-	hasNotGAFunc4ExprIdx bool
-	otherErr             error
+	hasIllegalFunc        bool
+	hasAggFunc            bool
+	hasRowVal             bool // hasRowVal checks whether the functional index refers to a row value
+	hasWindowFunc         bool
+	hasNotGAFunc4ExprIdx  bool
+	hasCastArrayFunc      bool
+	disallowCastArrayFunc bool
+	otherErr              error
 }
 
 func (c *illegalFunctionChecker) Enter(inNode ast.Node) (outNode ast.Node, skipChildren bool) {
@@ -308,7 +310,14 @@ func (c *illegalFunctionChecker) Enter(inNode ast.Node) (outNode ast.Node, skipC
 	case *ast.WindowFuncExpr:
 		c.hasWindowFunc = true
 		return inNode, true
+	case *ast.FuncCastExpr:
+		c.hasCastArrayFunc = c.hasCastArrayFunc || node.Tp.IsArray()
+		if c.disallowCastArrayFunc && node.Tp.IsArray() {
+			c.otherErr = expression.ErrNotSupportedYet.GenWithStackByArgs("Use of CAST( .. AS .. ARRAY) outside of functional index in CREATE(non-SELECT)/ALTER TABLE or in general expressions")
+			return inNode, true
+		}
 	}
+	c.disallowCastArrayFunc = true
 	return inNode, false
 }
 
@@ -355,6 +364,9 @@ func checkIllegalFn4Generated(name string, genType int, expr ast.ExprNode) error
 	if genType == typeIndex && c.hasNotGAFunc4ExprIdx && !config.GetGlobalConfig().Experimental.AllowsExpressionIndex {
 		return dbterror.ErrUnsupportedExpressionIndex
 	}
+	if genType == typeColumn && c.hasCastArrayFunc {
+		return expression.ErrNotSupportedYet.GenWithStackByArgs("Use of CAST( .. AS .. ARRAY) outside of functional index in CREATE(non-SELECT)/ALTER TABLE or in general expressions")
+	}
 	return nil
 }
 

ddl/index.go

@@ -64,26 +64,28 @@ var (
 	telemetryAddIndexIngestUsage = metrics.TelemetryAddIndexIngestCnt
 )
 
-func buildIndexColumns(ctx sessionctx.Context, columns []*model.ColumnInfo, indexPartSpecifications []*ast.IndexPartSpecification) ([]*model.IndexColumn, error) {
+func buildIndexColumns(ctx sessionctx.Context, columns []*model.ColumnInfo, indexPartSpecifications []*ast.IndexPartSpecification) ([]*model.IndexColumn, bool, error) {
 	// Build offsets.
 	idxParts := make([]*model.IndexColumn, 0, len(indexPartSpecifications))
 	var col *model.ColumnInfo
+	var mvIndex bool
 	maxIndexLength := config.GetGlobalConfig().MaxIndexLength
 	// The sum of length of all index columns.
 	sumLength := 0
 	for _, ip := range indexPartSpecifications {
 		col = model.FindColumnInfo(columns, ip.Column.Name.L)
 		if col == nil {
-			return nil, dbterror.ErrKeyColumnDoesNotExits.GenWithStack("column does not exist: %s", ip.Column.Name)
+			return nil, false, dbterror.ErrKeyColumnDoesNotExits.GenWithStack("column does not exist: %s", ip.Column.Name)
 		}
 
 		if err := checkIndexColumn(ctx, col, ip.Length); err != nil {
-			return nil, err
+			return nil, false, err
 		}
+		mvIndex = mvIndex || col.FieldType.IsArray()
 		indexColLen := ip.Length
 		indexColumnLength, err := getIndexColumnLength(col, ip.Length)
 		if err != nil {
-			return nil, err
+			return nil, false, err
 		}
 		sumLength += indexColumnLength
 
@@ -92,12 +94,12 @@ func buildIndexColumns(ctx sessionctx.Context, columns []*model.ColumnInfo, inde
 			// The multiple column index and the unique index in which the length sum exceeds the maximum size
 			// will return an error instead produce a warning.
 			if ctx == nil || ctx.GetSessionVars().StrictSQLMode || mysql.HasUniKeyFlag(col.GetFlag()) || len(indexPartSpecifications) > 1 {
-				return nil, dbterror.ErrTooLongKey.GenWithStackByArgs(maxIndexLength)
+				return nil, false, dbterror.ErrTooLongKey.GenWithStackByArgs(maxIndexLength)
 			}
 			// truncate index length and produce warning message in non-restrict sql mode.
 			colLenPerUint, err := getIndexColumnLength(col, 1)
 			if err != nil {
-				return nil, err
+				return nil, false, err
 			}
 			indexColLen = maxIndexLength / colLenPerUint
 			// produce warning message
@@ -111,7 +113,7 @@ func buildIndexColumns(ctx sessionctx.Context, columns []*model.ColumnInfo, inde
 		})
 	}
 
-	return idxParts, nil
+	return idxParts, mvIndex, nil
 }
 
 // CheckPKOnGeneratedColumn checks the specification of PK is valid.
@@ -154,7 +156,7 @@ func checkIndexColumn(ctx sessionctx.Context, col *model.ColumnInfo, indexColumn
 	}
 
 	// JSON column cannot index.
-	if col.FieldType.GetType() == mysql.TypeJSON {
+	if col.FieldType.GetType() == mysql.TypeJSON && !col.FieldType.IsArray() {
 		if col.Hidden {
 			return dbterror.ErrFunctionalIndexOnJSONOrGeometryFunction
 		}
@@ -263,7 +265,7 @@ func BuildIndexInfo(
 		return nil, errors.Trace(err)
 	}
 
-	idxColumns, err := buildIndexColumns(ctx, allTableColumns, indexPartSpecifications)
+	idxColumns, mvIndex, err := buildIndexColumns(ctx, allTableColumns, indexPartSpecifications)
 	if err != nil {
 		return nil, errors.Trace(err)
 	}
@@ -276,6 +278,7 @@ func BuildIndexInfo(
 		Primary: isPrimary,
 		Unique:  isUnique,
 		Global:  isGlobal,
+		MVIndex: mvIndex,
 	}
 
 	if indexOption != nil {

ddl/partition.go

@@ -1375,7 +1375,7 @@ func checkPartitionFuncType(ctx sessionctx.Context, expr ast.ExprNode, tblInfo *
 		return nil
 	}
 
-	e, err := expression.RewriteSimpleExprWithTableInfo(ctx, tblInfo, expr)
+	e, err := expression.RewriteSimpleExprWithTableInfo(ctx, tblInfo, expr, false)
 	if err != nil {
 		return errors.Trace(err)
 	}

expression/BUILD.bazel

@@ -177,6 +177,7 @@ go_test(
         "integration_serial_test.go",
         "integration_test.go",
         "main_test.go",
+        "multi_valued_index_test.go",
         "scalar_function_test.go",
         "schema_test.go",
         "typeinfer_test.go",

expression/builtin_cast.go

@@ -23,6 +23,7 @@
 package expression
 
 import (
+	"fmt"
 	"math"
 	"strconv"
 	"strings"
@@ -407,6 +408,70 @@ func (c *castAsDurationFunctionClass) getFunction(ctx sessionctx.Context, args [
 	return sig, nil
 }
 
+type castAsArrayFunctionClass struct {
+	baseFunctionClass
+
+	tp *types.FieldType
+}
+
+func (c *castAsArrayFunctionClass) verifyArgs(args []Expression) error {
+	if err := c.baseFunctionClass.verifyArgs(args); err != nil {
+		return err
+	}
+
+	if args[0].GetType().EvalType() != types.ETJson {
+		return types.ErrInvalidJSONData.GenWithStackByArgs("1", "cast_as_array")
+	}
+
+	return nil
+}
+
+func (c *castAsArrayFunctionClass) getFunction(ctx sessionctx.Context, args []Expression) (sig builtinFunc, err error) {
+	if err := c.verifyArgs(args); err != nil {
+		return nil, err
+	}
+	arrayType := c.tp.ArrayType()
+	switch arrayType.GetType() {
+	case mysql.TypeYear, mysql.TypeJSON:
+		return nil, ErrNotSupportedYet.GenWithStackByArgs(fmt.Sprintf("CAST-ing data to array of %s", arrayType.String()))
+	}
+	if arrayType.EvalType() == types.ETString && arrayType.GetCharset() != charset.CharsetUTF8MB4 && arrayType.GetCharset() != charset.CharsetBin {
+		return nil, ErrNotSupportedYet.GenWithStackByArgs("specifying charset for multi-valued index", arrayType.String())
+	}
+
+	bf, err := newBaseBuiltinFunc(ctx, c.funcName, args, c.tp)
+	if err != nil {
+		return nil, err
+	}
+	sig = &castJSONAsArrayFunctionSig{bf}
+	return sig, nil
+}
+
+type castJSONAsArrayFunctionSig struct {
+	baseBuiltinFunc
+}
+
+func (b *castJSONAsArrayFunctionSig) Clone() builtinFunc {
+	newSig := &castJSONAsArrayFunctionSig{}
+	newSig.cloneFrom(&b.baseBuiltinFunc)
+	return newSig
+}
+
+func (b *castJSONAsArrayFunctionSig) evalJSON(row chunk.Row) (res types.BinaryJSON, isNull bool, err error) {
+	val, isNull, err := b.args[0].EvalJSON(b.ctx, row)
+	if isNull || err != nil {
+		return res, isNull, err
+	}
+
+	if val.TypeCode != types.JSONTypeCodeArray {
+		return types.BinaryJSON{}, false, ErrNotSupportedYet.GenWithStackByArgs("CAST-ing Non-JSON Array type to array")
+	}
+
+	// TODO: impl the cast(... as ... array) function
+
+	return types.BinaryJSON{}, false, nil
+}
+
 type castAsJSONFunctionClass struct {
 	baseFunctionClass
 
@@ -1914,6 +1979,13 @@ func BuildCastCollationFunction(ctx sessionctx.Context, expr Expression, ec *Exp
 
 // BuildCastFunction builds a CAST ScalarFunction from the Expression.
 func BuildCastFunction(ctx sessionctx.Context, expr Expression, tp *types.FieldType) (res Expression) {
+	res, err := BuildCastFunctionWithCheck(ctx, expr, tp)
+	terror.Log(err)
+	return
+}
+
+// BuildCastFunctionWithCheck builds a CAST ScalarFunction from the Expression and return error if any.
+func BuildCastFunctionWithCheck(ctx sessionctx.Context, expr Expression, tp *types.FieldType) (res Expression, err error) {
 	argType := expr.GetType()
 	// If source argument's nullable, then target type should be nullable
 	if !mysql.HasNotNullFlag(argType.GetFlag()) {
@@ -1933,15 +2005,18 @@ func BuildCastFunction(ctx sessionctx.Context, expr Expression, tp *types.FieldT
 	case types.ETDuration:
 		fc = &castAsDurationFunctionClass{baseFunctionClass{ast.Cast, 1, 1}, tp}
 	case types.ETJson:
-		fc = &castAsJSONFunctionClass{baseFunctionClass{ast.Cast, 1, 1}, tp}
+		if tp.IsArray() {
+			fc = &castAsArrayFunctionClass{baseFunctionClass{ast.Cast, 1, 1}, tp}
+		} else {
+			fc = &castAsJSONFunctionClass{baseFunctionClass{ast.Cast, 1, 1}, tp}
+		}
 	case types.ETString:
 		fc = &castAsStringFunctionClass{baseFunctionClass{ast.Cast, 1, 1}, tp}
 		if expr.GetType().GetType() == mysql.TypeBit {
 			tp.SetFlen((expr.GetType().GetFlen() + 7) / 8)
 		}
 	}
 	f, err := fc.getFunction(ctx, []Expression{expr})
-	terror.Log(err)
 	res = &ScalarFunction{
 		FuncName: model.NewCIStr(ast.Cast),
 		RetType:  tp,
@@ -1950,10 +2025,10 @@ func BuildCastFunction(ctx sessionctx.Context, expr Expression, tp *types.FieldT
 	// We do not fold CAST if the eval type of this scalar function is ETJson
 	// since we may reset the flag of the field type of CastAsJson later which
 	// would affect the evaluation of it.
-	if tp.EvalType() != types.ETJson {
+	if tp.EvalType() != types.ETJson && err == nil {
 		res = FoldConstant(res)
 	}
-	return res
+	return res, err
 }
 
 // WrapWithCastAsInt wraps `expr` with `cast` if the return type of expr is not

expression/errors.go

@@ -37,6 +37,7 @@ var (
 	ErrInvalidTableSample          = dbterror.ClassExpression.NewStd(mysql.ErrInvalidTableSample)
 	ErrInternal                    = dbterror.ClassOptimizer.NewStd(mysql.ErrInternal)
 	ErrNoDB                        = dbterror.ClassOptimizer.NewStd(mysql.ErrNoDB)
+	ErrNotSupportedYet             = dbterror.ClassExpression.NewStd(mysql.ErrNotSupportedYet)
 
 	// All the un-exported errors are defined here:
 	errFunctionNotExists             = dbterror.ClassExpression.NewStd(mysql.ErrSpDoesNotExist)

expression/expression.go

@@ -59,7 +59,7 @@ var EvalAstExpr func(sctx sessionctx.Context, expr ast.ExprNode) (types.Datum, e
 // RewriteAstExpr rewrites ast expression directly.
 // Note: initialized in planner/core
 // import expression and planner/core together to use EvalAstExpr
-var RewriteAstExpr func(sctx sessionctx.Context, expr ast.ExprNode, schema *Schema, names types.NameSlice) (Expression, error)
+var RewriteAstExpr func(sctx sessionctx.Context, expr ast.ExprNode, schema *Schema, names types.NameSlice, allowCastArray bool) (Expression, error)
 
 // VecExpr contains all vectorized evaluation methods.
 type VecExpr interface {
@@ -998,7 +998,7 @@ func ColumnInfos2ColumnsAndNames(ctx sessionctx.Context, dbName, tblName model.C
 			if err != nil {
 				return nil, nil, errors.Trace(err)
 			}
-			e, err := RewriteAstExpr(ctx, expr, mockSchema, names)
+			e, err := RewriteAstExpr(ctx, expr, mockSchema, names, false)
 			if err != nil {
 				return nil, nil, errors.Trace(err)
 			}

expression/multi_valued_index_test.go

@@ -0,0 +1,47 @@
+// Copyright 2022 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 expression_test
+
+import (
+	"testing"
+
+	"github.com/pingcap/tidb/errno"
+	"github.com/pingcap/tidb/testkit"
+)
+
+func TestMultiValuedIndexDDL(t *testing.T) {
+	store := testkit.CreateMockStore(t)
+
+	tk := testkit.NewTestKit(t, store)
+	tk.MustExec("USE test;")
+
+	tk.MustExec("create table t(a json);")
+	tk.MustGetErrCode("select cast(a as signed array) from t", errno.ErrNotSupportedYet)
+	tk.MustGetErrCode("select json_extract(cast(a as signed array), '$[0]') from t", errno.ErrNotSupportedYet)
+	tk.MustGetErrCode("select * from t where cast(a as signed array)", errno.ErrNotSupportedYet)
+	tk.MustGetErrCode("select cast('[1,2,3]' as unsigned array);", errno.ErrNotSupportedYet)
+
+	tk.MustExec("drop table t")
+	tk.MustGetErrCode("CREATE TABLE t(x INT, KEY k ((1 AND CAST(JSON_ARRAY(x) AS UNSIGNED ARRAY))));", errno.ErrNotSupportedYet)
+	tk.MustGetErrCode("CREATE TABLE t1 (f1 json, key mvi((cast(cast(f1 as unsigned array) as unsigned array))));", errno.ErrNotSupportedYet)
+	tk.MustGetErrCode("CREATE TABLE t1 (f1 json, key mvi((cast(f1->>'$[*]' as unsigned array))));", errno.ErrInvalidJSONData)
+	tk.MustGetErrCode("CREATE TABLE t1 (f1 json, key mvi((cast(f1->'$[*]' as year array))));", errno.ErrNotSupportedYet)
+	tk.MustGetErrCode("CREATE TABLE t1 (f1 json, key mvi((cast(f1->'$[*]' as json array))));", errno.ErrNotSupportedYet)
+	tk.MustGetErrCode("CREATE TABLE t1 (f1 json, key mvi((cast(f1->'$[*]' as char(10) charset gbk array))));", errno.ErrNotSupportedYet)
+	tk.MustGetErrCode("create table t(j json, gc json as ((concat(cast(j->'$[*]' as unsigned array),\"x\"))));", errno.ErrNotSupportedYet)
+	tk.MustGetErrCode("create table t(j json, gc json as (cast(j->'$[*]' as unsigned array)));", errno.ErrNotSupportedYet)
+	tk.MustGetErrCode("create view v as select cast('[1,2,3]' as unsigned array);", errno.ErrNotSupportedYet)
+	tk.MustExec("create table t(a json, index idx((cast(a as signed array))));")
+}