diff --git a/ddl/db_partition_test.go b/ddl/db_partition_test.go
index c0e087ef4a046..fbf8a3782378f 100644
--- a/ddl/db_partition_test.go
+++ b/ddl/db_partition_test.go
@@ -4662,4 +4662,73 @@ func TestAlterModifyColumnOnPartitionedTable(t *testing.T) {
 		"34 34💥",
 		"46 46",
 		"57 57"))
+	tk.MustGetErrCode(`alter table t modify a varchar(20)`, errno.ErrUnsupportedDDLOperation)
+}
+
+func TestAlterModifyColumnOnPartitionedTableFail(t *testing.T) {
+	store := testkit.CreateMockStore(t)
+	tk := testkit.NewTestKit(t, store)
+	schemaName := "modColPartFail"
+	tk.MustExec("create database " + schemaName)
+	tk.MustExec("use " + schemaName)
+	tk.MustExec(`create table t (a int unsigned, b varchar(255), key (b)) partition by range (a) (partition p0 values less than (10), partition p1 values less than (20), partition pMax values less than (MAXVALUE))`)
+	tk.MustExec(`insert into t values (7, "07"), (8, "08"),(23,"23"),(34,"34💥"),(46,"46"),(57,"57")`)
+	tk.MustGetErrCode(`alter table t modify a varchar(255)`, errno.ErrUnsupportedDDLOperation)
+	tk.MustGetErrCode(`alter table t modify a float`, mysql.ErrFieldTypeNotAllowedAsPartitionField)
+	tk.MustExec(`drop table t`)
+	tk.MustExec(`create table t (b int unsigned, a varchar(255), key (b)) partition by range columns (a) (partition p0 values less than (""), partition p1 values less than ("11111"), partition pMax values less than (MAXVALUE))`)
+	tk.MustExec(`insert into t values (7, "07"), (8, "08"),(23,"23"),(34,"34 💥💥Longer than 11111"),(46,"46"),(57,"57")`)
+	tk.MustExec(`alter table t modify a varchar(50)`)
+	tk.MustGetErrCode(`alter table t modify a float`, mysql.ErrFieldTypeNotAllowedAsPartitionField)
+	tk.MustGetErrCode(`alter table t modify a int`, errno.ErrUnsupportedDDLOperation)
+	tk.MustContainErrMsg(`alter table t modify a varchar(4)`, "[ddl:8200]New column does not match partition definitions: [ddl:1654]Partition column values of incorrect type")
+	tk.MustGetErrCode(`alter table t modify a varchar(5)`, errno.WarnDataTruncated)
+	tk.MustExec(`SET SQL_MODE = ''`)
+	tk.MustExec(`alter table t modify a varchar(5)`)
+	// TODO: Investigate why there are no warnings here?!?
+	tk.MustQuery(`show warnings`).Check(testkit.Rows())
+	tk.MustExec(`SET SQL_MODE = DEFAULT`)
+	tk.MustQuery(`select * from t`).Sort().Check(testkit.Rows(""+
+		"23 23",
+		"34 34 💥💥",
+		"46 46",
+		"57 57",
+		"7 07",
+		"8 08"))
+	tStr := "" +
+		"CREATE TABLE `t` (\n" +
+		"  `b` int(10) unsigned DEFAULT NULL,\n" +
+		"  `a` varchar(5) DEFAULT NULL,\n" +
+		"  KEY `b` (`b`)\n" +
+		") ENGINE=InnoDB DEFAULT CHARSET=utf8mb4 COLLATE=utf8mb4_bin\n" +
+		"PARTITION BY RANGE COLUMNS(`a`)\n" +
+		"(PARTITION `p0` VALUES LESS THAN (''),\n" +
+		" PARTITION `p1` VALUES LESS THAN ('11111'),\n" +
+		" PARTITION `pMax` VALUES LESS THAN (MAXVALUE))"
+	tk.MustQuery(`show create table t`).Check(testkit.Rows("t " + tStr))
+	tk.MustExec(`drop table t`)
+	tk.MustExec(tStr)
+	tk.MustExec(`drop table t`)
+	tk.MustExec("create table t (a int, b varchar(255), key (b)) partition by range (a) (partition `p-300` values less than (-300), partition p0 values less than (0), partition p300 values less than (300))")
+	tk.MustExec(`insert into t values (-400, "-400"), (-100, "-100"), (0, "0"), (100, "100"), (290, "290")`)
+	tk.MustContainErrMsg(`alter table t modify a int unsigned`, "[ddl:8200]Unsupported modify column, decreasing length of int may result in truncation and change of partition")
+	tk.MustContainErrMsg(`alter table t modify a tinyint`, "[ddl:8200]Unsupported modify column, decreasing length of int may result in truncation and change of partition")
+	tk.MustExec(`set sql_mode = ''`)
+	tk.MustContainErrMsg(`alter table t modify a tinyint`, "[ddl:8200]Unsupported modify column, decreasing length of int may result in truncation and change of partition")
+	tk.MustQuery("select * from t partition (`p-300`)").Sort().Check(testkit.Rows("-400 -400"))
+	tk.MustExec(`set sql_mode = default`)
+	tk.MustContainErrMsg(`alter table t modify a smallint`, "[ddl:8200]Unsupported modify column, decreasing length of int may result in truncation and change of partition")
+	tk.MustExec(`alter table t modify a bigint`)
+	tk.MustExec(`drop table t`)
+	tk.MustExec("create table t (a int, b varchar(255), key (b)) partition by range columns (a) (partition `p-300` values less than (-300), partition p0 values less than (0), partition p300 values less than (300))")
+	tk.MustExec(`insert into t values (-400, "-400"), (-100, "-100"), (0, "0"), (100, "100"), (290, "290")`)
+	tk.MustContainErrMsg(`alter table t modify a int unsigned`, "[ddl:8200]Unsupported modify column: can't change the partitioning column, since it would require reorganize all partitions")
+	tk.MustContainErrMsg(`alter table t modify a tinyint`, "[ddl:8200]New column does not match partition definitions: [ddl:1654]Partition column values of incorrect type")
+	tk.MustExec(`set sql_mode = ''`)
+	tk.MustContainErrMsg(`alter table t modify a tinyint`, "[ddl:8200]New column does not match partition definitions: [ddl:1654]Partition column values of incorrect type")
+	tk.MustQuery("select * from t partition (`p-300`)").Sort().Check(testkit.Rows("-400 -400"))
+	tk.MustExec(`set sql_mode = default`)
+	// OK to decrease, since with RANGE COLUMNS, it will check the partition definition values against the new type
+	tk.MustExec(`alter table t modify a smallint`)
+	tk.MustExec(`alter table t modify a bigint`)
 }
diff --git a/ddl/ddl_api.go b/ddl/ddl_api.go
index a0ee1310fa9f1..e9a502877c384 100644
--- a/ddl/ddl_api.go
+++ b/ddl/ddl_api.go
@@ -38,6 +38,7 @@ import (
 	"github.com/pingcap/tidb/infoschema"
 	"github.com/pingcap/tidb/kv"
 	"github.com/pingcap/tidb/meta/autoid"
+	"github.com/pingcap/tidb/parser"
 	"github.com/pingcap/tidb/parser/ast"
 	"github.com/pingcap/tidb/parser/charset"
 	"github.com/pingcap/tidb/parser/format"
@@ -2789,23 +2790,30 @@ func checkPartitionByList(ctx sessionctx.Context, tbInfo *model.TableInfo) error
 	return checkListPartitionValue(ctx, tbInfo)
 }
 
+func isColTypeAllowedAsPartitioningCol(fieldType types.FieldType) bool {
+	// The permitted data types are shown in the following list:
+	// All integer types
+	// DATE and DATETIME
+	// CHAR, VARCHAR, BINARY, and VARBINARY
+	// See https://dev.mysql.com/doc/mysql-partitioning-excerpt/5.7/en/partitioning-columns.html
+	// Note that also TIME is allowed in MySQL. Also see https://bugs.mysql.com/bug.php?id=84362
+	switch fieldType.GetType() {
+	case mysql.TypeTiny, mysql.TypeShort, mysql.TypeInt24, mysql.TypeLong, mysql.TypeLonglong:
+	case mysql.TypeDate, mysql.TypeDatetime, mysql.TypeDuration:
+	case mysql.TypeVarchar, mysql.TypeString:
+	default:
+		return false
+	}
+	return true
+}
+
 func checkColumnsPartitionType(tbInfo *model.TableInfo) error {
 	for _, col := range tbInfo.Partition.Columns {
 		colInfo := tbInfo.FindPublicColumnByName(col.L)
 		if colInfo == nil {
 			return errors.Trace(dbterror.ErrFieldNotFoundPart)
 		}
-		// The permitted data types are shown in the following list:
-		// All integer types
-		// DATE and DATETIME
-		// CHAR, VARCHAR, BINARY, and VARBINARY
-		// See https://dev.mysql.com/doc/mysql-partitioning-excerpt/5.7/en/partitioning-columns.html
-		// Note that also TIME is allowed in MySQL. Also see https://bugs.mysql.com/bug.php?id=84362
-		switch colInfo.FieldType.GetType() {
-		case mysql.TypeTiny, mysql.TypeShort, mysql.TypeInt24, mysql.TypeLong, mysql.TypeLonglong:
-		case mysql.TypeDate, mysql.TypeDatetime, mysql.TypeDuration:
-		case mysql.TypeVarchar, mysql.TypeString:
-		default:
+		if !isColTypeAllowedAsPartitioningCol(colInfo.FieldType) {
 			return dbterror.ErrNotAllowedTypeInPartition.GenWithStackByArgs(col.O)
 		}
 	}
@@ -4562,6 +4570,91 @@ func GetModifiableColumnJob(
 		}
 	}
 
+	// Check that the column change does not affect the partitioning column
+	// It must keep the same type, int [unsigned], [var]char, date[time]
+	if t.Meta().Partition != nil {
+		pt, ok := t.(table.PartitionedTable)
+		if !ok {
+			// Should never happen!
+			return nil, dbterror.ErrNotAllowedTypeInPartition.GenWithStackByArgs(newCol.Name.O)
+		}
+		isPartitioningColumn := false
+		for _, name := range pt.GetPartitionColumnNames() {
+			if strings.EqualFold(name.L, col.Name.L) {
+				isPartitioningColumn = true
+			}
+		}
+		if isPartitioningColumn {
+			if !isColTypeAllowedAsPartitioningCol(newCol.FieldType) {
+				return nil, dbterror.ErrNotAllowedTypeInPartition.GenWithStackByArgs(newCol.Name.O)
+			}
+			pi := pt.Meta().GetPartitionInfo()
+			if len(pi.Columns) == 0 {
+				// non COLUMNS partitioning, only checks INTs, not their actual range
+				// There are many edge cases, like when truncating SQL Mode is allowed
+				// which will change the partitioning expression value resulting in a
+				// different partition. Better be safe and not allow decreasing of length.
+				// TODO: Should we allow it in strict mode? Wait for a use case / request.
+				if newCol.FieldType.GetFlen() < col.FieldType.GetFlen() {
+					return nil, dbterror.ErrUnsupportedModifyCollation.GenWithStack("Unsupported modify column, decreasing length of int may result in truncation and change of partition")
+				}
+			}
+			// TODO: Test with LIST partitioning and decreasing the length so it is shorter
+			// than existing partition definitions. (RANGE is OK, since LESS THAN)
+
+			// Basically only allow changes of the length/decimals for the column
+			// Note that enum is not allowed, so elems are not checked
+			// TODO: support partition by ENUM
+			if newCol.FieldType.EvalType() != col.FieldType.EvalType() ||
+				newCol.FieldType.GetFlag() != col.FieldType.GetFlag() ||
+				newCol.FieldType.GetCollate() != col.FieldType.GetCollate() ||
+				newCol.FieldType.GetCharset() != col.FieldType.GetCharset() {
+				return nil, dbterror.ErrUnsupportedModifyColumn.GenWithStackByArgs("can't change the partitioning column, since it would require reorganize all partitions")
+			}
+			// Generate a new PartitionInfo and validate it together with the new column definition
+			// Checks if all partition definition values are compatible.
+			// Similar to what buildRangePartitionDefinitions would do in terms of checks.
+			// Try 1: Test generating the string, then parse it with the new column?
+			//func buildPartitionDefinitionsInfo(ctx sessionctx.Context, defs []*ast.PartitionDefinition, tbInfo *model.TableInfo) (partitions []model.PartitionDefinition, err error) {
+
+			// TODO: do not allow truncations, not even if not Strict SQLMode!!!
+
+			tblInfo := pt.Meta()
+			newTblInfo := *tblInfo
+			// Replace col with newCol and see if we can generate a new SHOW CREATE TABLE
+			// and reparse it and build new partition definitions (which will do additional
+			// checks columns vs partition definition values
+			newCols := make([]*model.ColumnInfo, 0, len(newTblInfo.Columns))
+			for _, c := range newTblInfo.Columns {
+				if c.ID == col.ID {
+					newCols = append(newCols, newCol.ColumnInfo)
+					continue
+				}
+				newCols = append(newCols, c)
+			}
+			newTblInfo.Columns = newCols
+			// TODO: Test and handle SQLMode?
+
+			var buf bytes.Buffer
+			AppendPartitionInfo(tblInfo.GetPartitionInfo(), &buf, mysql.ModeNone)
+			// The parser supports ALTER TABLE ... PARTITION BY ... even if the ddl code does not yet :)
+			// Ignoring warnings
+			stmt, _, err := parser.New().ParseSQL("ALTER TABLE t " + buf.String())
+			if err != nil {
+				// Should never happen!
+				return nil, dbterror.ErrUnsupportedModifyColumn.GenWithStack("cannot parse generated PartitionInfo")
+			}
+			at, ok := stmt[0].(*ast.AlterTableStmt)
+			if !ok || len(at.Specs) != 1 || at.Specs[0].Partition == nil {
+				return nil, dbterror.ErrUnsupportedModifyColumn.GenWithStack("cannot parse generated PartitionInfo")
+			}
+			pAst := at.Specs[0].Partition
+			if _, err = buildPartitionDefinitionsInfo(sctx, pAst.Definitions, &newTblInfo); err != nil {
+				return nil, dbterror.ErrUnsupportedModifyColumn.GenWithStack("New column does not match partition definitions: %s", err.Error())
+			}
+		}
+	}
+
 	// We don't support modifying column from not_auto_increment to auto_increment.
 	if !mysql.HasAutoIncrementFlag(col.GetFlag()) && mysql.HasAutoIncrementFlag(newCol.GetFlag()) {
 		return nil, dbterror.ErrUnsupportedModifyColumn.GenWithStackByArgs("can't set auto_increment")
diff --git a/ddl/partition.go b/ddl/partition.go
index c9a00a52fe5ec..5a6a5b561b146 100644
--- a/ddl/partition.go
+++ b/ddl/partition.go
@@ -2807,6 +2807,54 @@ func hexIfNonPrint(s string) string {
 	return "0x" + hex.EncodeToString([]byte(driver.UnwrapFromSingleQuotes(s)))
 }
 
+// AppendPartitionInfo is used in SHOW CREATE TABLE as well as generation the SQL syntax
+// for the PartitionInfo during validation of various DDL commands
+func AppendPartitionInfo(partitionInfo *model.PartitionInfo, buf *bytes.Buffer, sqlMode mysql.SQLMode) {
+	if partitionInfo == nil {
+		return
+	}
+	// Since MySQL 5.1/5.5 is very old and TiDB aims for 5.7/8.0 compatibility, we will not
+	// include the /*!50100 or /*!50500 comments for TiDB.
+	// This also solves the issue with comments within comments that would happen for
+	// PLACEMENT POLICY options.
+	if partitionInfo.Type == model.PartitionTypeHash {
+		defaultPartitionDefinitions := true
+		for i, def := range partitionInfo.Definitions {
+			if def.Name.O != fmt.Sprintf("p%d", i) {
+				defaultPartitionDefinitions = false
+				break
+			}
+			if len(def.Comment) > 0 || def.PlacementPolicyRef != nil {
+				defaultPartitionDefinitions = false
+				break
+			}
+		}
+
+		if defaultPartitionDefinitions {
+			fmt.Fprintf(buf, "\nPARTITION BY HASH (%s) PARTITIONS %d", partitionInfo.Expr, partitionInfo.Num)
+			return
+		}
+	}
+	// this if statement takes care of lists/range columns case
+	if len(partitionInfo.Columns) > 0 {
+		// partitionInfo.Type == model.PartitionTypeRange || partitionInfo.Type == model.PartitionTypeList
+		// Notice that MySQL uses two spaces between LIST and COLUMNS...
+		fmt.Fprintf(buf, "\nPARTITION BY %s COLUMNS(", partitionInfo.Type.String())
+		for i, col := range partitionInfo.Columns {
+			buf.WriteString(stringutil.Escape(col.O, sqlMode))
+			if i < len(partitionInfo.Columns)-1 {
+				buf.WriteString(",")
+			}
+		}
+		buf.WriteString(")\n(")
+	} else {
+		fmt.Fprintf(buf, "\nPARTITION BY %s (%s)\n(", partitionInfo.Type.String(), partitionInfo.Expr)
+	}
+
+	AppendPartitionDefs(partitionInfo, buf, sqlMode)
+	buf.WriteString(")")
+}
+
 // AppendPartitionDefs generates a list of partition definitions needed for SHOW CREATE TABLE (in executor/show.go)
 // as well as needed for generating the ADD PARTITION query for INTERVAL partitioning of ALTER TABLE t LAST PARTITION
 // and generating the CREATE TABLE query from CREATE TABLE ... INTERVAL
diff --git a/executor/show.go b/executor/show.go
index 03f694fc504e1..070e95c650101 100644
--- a/executor/show.go
+++ b/executor/show.go
@@ -1216,7 +1216,7 @@ func ConstructResultOfShowCreateTable(ctx sessionctx.Context, tableInfo *model.T
 	}
 
 	// add partition info here.
-	appendPartitionInfo(tableInfo.Partition, buf, sqlMode)
+	ddl.AppendPartitionInfo(tableInfo.Partition, buf, sqlMode)
 	return nil
 }
 
@@ -1349,52 +1349,6 @@ func fetchShowCreateTable4View(ctx sessionctx.Context, tb *model.TableInfo, buf
 	fmt.Fprintf(buf, ") AS %s", tb.View.SelectStmt)
 }
 
-func appendPartitionInfo(partitionInfo *model.PartitionInfo, buf *bytes.Buffer, sqlMode mysql.SQLMode) {
-	if partitionInfo == nil {
-		return
-	}
-	// Since MySQL 5.1/5.5 is very old and TiDB aims for 5.7/8.0 compatibility, we will not
-	// include the /*!50100 or /*!50500 comments for TiDB.
-	// This also solves the issue with comments within comments that would happen for
-	// PLACEMENT POLICY options.
-	if partitionInfo.Type == model.PartitionTypeHash {
-		defaultPartitionDefinitions := true
-		for i, def := range partitionInfo.Definitions {
-			if def.Name.O != fmt.Sprintf("p%d", i) {
-				defaultPartitionDefinitions = false
-				break
-			}
-			if len(def.Comment) > 0 || def.PlacementPolicyRef != nil {
-				defaultPartitionDefinitions = false
-				break
-			}
-		}
-
-		if defaultPartitionDefinitions {
-			fmt.Fprintf(buf, "\nPARTITION BY HASH (%s) PARTITIONS %d", partitionInfo.Expr, partitionInfo.Num)
-			return
-		}
-	}
-	// this if statement takes care of lists/range columns case
-	if len(partitionInfo.Columns) > 0 {
-		// partitionInfo.Type == model.PartitionTypeRange || partitionInfo.Type == model.PartitionTypeList
-		// Notice that MySQL uses two spaces between LIST and COLUMNS...
-		fmt.Fprintf(buf, "\nPARTITION BY %s COLUMNS(", partitionInfo.Type.String())
-		for i, col := range partitionInfo.Columns {
-			buf.WriteString(stringutil.Escape(col.O, sqlMode))
-			if i < len(partitionInfo.Columns)-1 {
-				buf.WriteString(",")
-			}
-		}
-		buf.WriteString(")\n(")
-	} else {
-		fmt.Fprintf(buf, "\nPARTITION BY %s (%s)\n(", partitionInfo.Type.String(), partitionInfo.Expr)
-	}
-
-	ddl.AppendPartitionDefs(partitionInfo, buf, sqlMode)
-	buf.WriteString(")")
-}
-
 // ConstructResultOfShowCreateDatabase constructs the result for show create database.
 func ConstructResultOfShowCreateDatabase(ctx sessionctx.Context, dbInfo *model.DBInfo, ifNotExists bool, buf *bytes.Buffer) (err error) {
 	sqlMode := ctx.GetSessionVars().SQLMode