util: let TypeFloat should be decoded as Float32 in Chunk (#35978)

.github/licenserc.yml

@@ -31,4 +31,5 @@ header:
     - 'dumpling/'
     - 'tidb-binlog/driver/example'
     - 'tidb-binlog/proto/go-binlog/secondary_binlog.pb.go'
+    - '**/*.sql'
   comment: on-failure

executor/analyze_test.go

@@ -18,6 +18,7 @@ import (
 	"context"
 	"encoding/json"
 	"fmt"
+	"io/ioutil"
 	"strconv"
 	"strings"
 	"sync"
@@ -3389,3 +3390,23 @@ PARTITION BY RANGE ( a ) (
 	tbl := h.GetTableStats(tableInfo)
 	require.Equal(t, int64(6), tbl.Columns[tableInfo.Columns[0].ID].Histogram.NDV)
 }
+
+func TestAnalyzePartitionTableForFloat(t *testing.T) {
+	store, clean := testkit.CreateMockStore(t)
+	defer clean()
+	tk := testkit.NewTestKit(t, store)
+	tk.MustExec("set @@tidb_partition_prune_mode='dynamic'")
+	tk.MustExec("use test")
+	tk.MustExec("CREATE TABLE t1 ( id bigint(20) unsigned NOT NULL AUTO_INCREMENT, num float(9,8) DEFAULT NULL, PRIMARY KEY (id)  ) ENGINE=InnoDB DEFAULT CHARSET=utf8mb4 COLLATE=utf8mb4_bin PARTITION BY HASH (id) PARTITIONS 128;")
+	// To reproduce the error we meet in https://github.com/pingcap/tidb/issues/35910, we should use the data provided in this issue
+	b, err := ioutil.ReadFile("testdata/analyze_test_data.sql")
+	require.NoError(t, err)
+	sqls := strings.Split(string(b), ";")
+	for _, sql := range sqls {
+		if len(sql) < 1 {
+			continue
+		}
+		tk.MustExec(sql)
+	}
+	tk.MustExec("analyze table t1")
+}

statistics/cmsketch.go

@@ -767,6 +767,8 @@ func MergePartTopN2GlobalTopN(sc *stmtctx.StatementContext, version int, topNs [
 						if types.IsTypeTime(hists[0].Tp.GetType()) {
 							// handle datetime values specially since they are encoded to int and we'll get int values if using DecodeOne.
 							_, d, err = codec.DecodeAsDateTime(val.Encoded, hists[0].Tp.GetType(), sc.TimeZone)
+						} else if types.IsTypeFloat(hists[0].Tp.GetType()) {
+							_, d, err = codec.DecodeAsFloat32(val.Encoded, hists[0].Tp.GetType())
 						} else {
 							_, d, err = codec.DecodeOne(val.Encoded)
 						}

statistics/histogram.go

@@ -2120,6 +2120,8 @@ func MergePartitionHist2GlobalHist(sc *stmtctx.StatementContext, hists []*Histog
 			if types.IsTypeTime(hists[0].Tp.GetType()) {
 				// handle datetime values specially since they are encoded to int and we'll get int values if using DecodeOne.
 				_, d, err = codec.DecodeAsDateTime(meta.Encoded, hists[0].Tp.GetType(), sc.TimeZone)
+			} else if types.IsTypeFloat(hists[0].Tp.GetType()) {
+				_, d, err = codec.DecodeAsFloat32(meta.Encoded, hists[0].Tp.GetType())
 			} else {
 				_, d, err = codec.DecodeOne(meta.Encoded)
 			}

types/datum.go

@@ -183,6 +183,12 @@ func (d *Datum) SetFloat32(f float32) {
 	d.i = int64(math.Float64bits(float64(f)))
 }
 
+// SetFloat32FromF64 sets float32 values from f64
+func (d *Datum) SetFloat32FromF64(f float64) {
+	d.k = KindFloat32
+	d.i = int64(math.Float64bits(f))
+}
+
 // GetString gets string value.
 func (d *Datum) GetString() string {
 	return string(hack.String(d.b))

types/etc.go

@@ -66,6 +66,11 @@ func IsTypeTime(tp byte) bool {
 	return tp == mysql.TypeDatetime || tp == mysql.TypeDate || tp == mysql.TypeTimestamp
 }
 
+// IsTypeFloat indicates whether the type is TypeFloat
+func IsTypeFloat(tp byte) bool {
+	return tp == mysql.TypeFloat
+}
+
 // IsTypeInteger returns a boolean indicating whether the tp is integer type.
 func IsTypeInteger(tp byte) bool {
 	switch tp {

util/codec/codec.go

@@ -762,6 +762,8 @@ func DecodeRange(b []byte, size int, idxColumnTypes []byte, loc *time.Location)
 			if types.IsTypeTime(idxColumnTypes[i]) {
 				// handle datetime values specially since they are encoded to int and we'll get int values if using DecodeOne.
 				b, d, err = DecodeAsDateTime(b, idxColumnTypes[i], loc)
+			} else if types.IsTypeFloat(idxColumnTypes[i]) {
+				b, d, err = DecodeAsFloat32(b, idxColumnTypes[i])
 			} else {
 				b, d, err = DecodeOne(b)
 			}
@@ -899,6 +901,22 @@ func DecodeAsDateTime(b []byte, tp byte, loc *time.Location) (remain []byte, d t
 	return b, d, nil
 }
 
+// DecodeAsFloat32 decodes value for mysql.TypeFloat
+func DecodeAsFloat32(b []byte, tp byte) (remain []byte, d types.Datum, err error) {
+	if len(b) < 1 || tp != mysql.TypeFloat {
+		return nil, d, errors.New("invalid encoded key")
+	}
+	flag := b[0]
+	b = b[1:]
+	if flag != floatFlag {
+		return b, d, errors.Errorf("invalid encoded key flag %v for DecodeAsFloat32", flag)
+	}
+	var v float64
+	b, v, err = DecodeFloat(b)
+	d.SetFloat32FromF64(v)
+	return b, d, nil
+}
+
 // CutOne cuts the first encoded value from b.
 // It will return the first encoded item and the remains as byte slice.
 func CutOne(b []byte) (data []byte, remain []byte, err error) {