executor: fix the wrong order by pk desc result and some corner cas…

…es for unsigned pk (#10179) (#10209)

executor/analyze.go

@@ -324,7 +324,7 @@ func (e *AnalyzeColumnsExec) open() error {
 		ranges = ranger.FullIntRange(false)
 	}
 	e.resultHandler = &tableResultHandler{}
-	firstPartRanges, secondPartRanges := splitRanges(ranges, e.keepOrder)
+	firstPartRanges, secondPartRanges := splitRanges(ranges, e.keepOrder, false)
 	firstResult, err := e.buildResp(firstPartRanges)
 	if err != nil {
 		return errors.Trace(err)

executor/distsql.go

@@ -156,7 +156,7 @@ func handleIsExtra(col *expression.Column) bool {
 	return false
 }
 
-func splitRanges(ranges []*ranger.Range, keepOrder bool) ([]*ranger.Range, []*ranger.Range) {
+func splitRanges(ranges []*ranger.Range, keepOrder bool, desc bool) ([]*ranger.Range, []*ranger.Range) {
 	if len(ranges) == 0 || ranges[0].LowVal[0].Kind() == types.KindInt64 {
 		return ranges, nil
 	}
@@ -170,27 +170,37 @@ func splitRanges(ranges []*ranger.Range, keepOrder bool) ([]*ranger.Range, []*ra
 		if !keepOrder {
 			return append(unsignedRanges, signedRanges...), nil
 		}
+		if desc {
+			return unsignedRanges, signedRanges
+		}
 		return signedRanges, unsignedRanges
 	}
 	signedRanges := make([]*ranger.Range, 0, idx+1)
 	unsignedRanges := make([]*ranger.Range, 0, len(ranges)-idx)
 	signedRanges = append(signedRanges, ranges[0:idx]...)
-	signedRanges = append(signedRanges, &ranger.Range{
-		LowVal:     ranges[idx].LowVal,
-		LowExclude: ranges[idx].LowExclude,
-		HighVal:    []types.Datum{types.NewUintDatum(math.MaxInt64)},
-	})
-	unsignedRanges = append(unsignedRanges, &ranger.Range{
-		LowVal:      []types.Datum{types.NewUintDatum(math.MaxInt64 + 1)},
-		HighVal:     ranges[idx].HighVal,
-		HighExclude: ranges[idx].HighExclude,
-	})
+	if !(ranges[idx].LowVal[0].GetUint64() == math.MaxInt64 && ranges[idx].LowExclude) {
+		signedRanges = append(signedRanges, &ranger.Range{
+			LowVal:     ranges[idx].LowVal,
+			LowExclude: ranges[idx].LowExclude,
+			HighVal:    []types.Datum{types.NewUintDatum(math.MaxInt64)},
+		})
+	}
+	if !(ranges[idx].HighVal[0].GetUint64() == math.MaxInt64+1 && ranges[idx].HighExclude) {
+		unsignedRanges = append(unsignedRanges, &ranger.Range{
+			LowVal:      []types.Datum{types.NewUintDatum(math.MaxInt64 + 1)},
+			HighVal:     ranges[idx].HighVal,
+			HighExclude: ranges[idx].HighExclude,
+		})
+	}
 	if idx < len(ranges) {
 		unsignedRanges = append(unsignedRanges, ranges[idx+1:]...)
 	}
 	if !keepOrder {
 		return append(unsignedRanges, signedRanges...), nil
 	}
+	if desc {
+		return unsignedRanges, signedRanges
+	}
 	return signedRanges, unsignedRanges
 }
 

executor/distsql_test.go

@@ -207,3 +207,15 @@ func (s *testSuite) TestUniqueKeyNullValueSelect(c *C) {
 	res = tk.MustQuery("select * from t where id is null;")
 	res.Check(testkit.Rows("<nil> a", "<nil> b", "<nil> c"))
 }
+
+// TestIssue10178 contains tests for https://github.com/pingcap/tidb/issues/10178 .
+func (s *testSuite) TestIssue10178(c *C) {
+	tk := testkit.NewTestKit(c, s.store)
+	tk.MustExec("use test")
+	tk.MustExec("drop table if exists t")
+	tk.MustExec("create table t(a bigint unsigned primary key)")
+	tk.MustExec("insert into t values(9223372036854775807), (18446744073709551615)")
+	tk.MustQuery("select max(a) from t").Check(testkit.Rows("18446744073709551615"))
+	tk.MustQuery("select * from t where a > 9223372036854775807").Check(testkit.Rows("18446744073709551615"))
+	tk.MustQuery("select * from t where a < 9223372036854775808").Check(testkit.Rows("9223372036854775807"))
+}

executor/table_reader.go

@@ -96,7 +96,7 @@ func (e *TableReaderExecutor) Open(ctx context.Context) error {
 	}
 
 	e.resultHandler = &tableResultHandler{}
-	firstPartRanges, secondPartRanges := splitRanges(e.ranges, e.keepOrder)
+	firstPartRanges, secondPartRanges := splitRanges(e.ranges, e.keepOrder, e.desc)
 	firstResult, err := e.buildResp(ctx, firstPartRanges)
 	if err != nil {
 		e.feedback.Invalidate()
@@ -161,10 +161,12 @@ func (e *TableReaderExecutor) buildResp(ctx context.Context, ranges []*ranger.Ra
 }
 
 type tableResultHandler struct {
-	// If the pk is unsigned and we have KeepOrder=true.
-	// optionalResult handles the request whose range is in signed int range.
-	// result handles the request whose range is exceed signed int range.
-	// Otherwise, we just set optionalFinished true and the result handles the whole ranges.
+	// If the pk is unsigned and we have KeepOrder=true and want ascending order,
+	// `optionalResult` will handles the request whose range is in signed int range, and
+	// `result` will handle the request whose range is exceed signed int range.
+	// If we want descending order, `optionalResult` will handles the request whose range is exceed signed, and
+	// the `result` will handle the request whose range is in signed.
+	// Otherwise, we just set `optionalFinished` true and the `result` handles the whole ranges.
 	optionalResult distsql.SelectResult
 	result         distsql.SelectResult