From d901863643afb1a40ae96b1ee800e8a8c6d5808a Mon Sep 17 00:00:00 2001
From: tangenta <tangenta@126.com>
Date: Wed, 15 Apr 2020 20:56:37 +0800
Subject: [PATCH] executor: insert negative primary key into auto_random table
 won't trigger rebase (#15397)

---
 executor/ddl_test.go      | 19 +++++++++++++++++++
 executor/insert_common.go |  3 +++
 util/testutil/testutil.go |  2 +-
 3 files changed, 23 insertions(+), 1 deletion(-)

diff --git a/executor/ddl_test.go b/executor/ddl_test.go
index 4196b9e046721..a40ad59b748a2 100644
--- a/executor/ddl_test.go
+++ b/executor/ddl_test.go
@@ -859,6 +859,25 @@ func (s *testAutoRandomSuite) TestAutoRandomBitsData(c *C) {
 	c.Assert(err, NotNil)
 	c.Assert(err.Error(), Equals, autoid.ErrAutoRandReadFailed.GenWithStackByArgs().Error())
 	tk.MustExec("drop table t")
+
+	// Test insert negative integers explicitly won't trigger rebase.
+	tk.MustExec("create table t (a bigint primary key auto_random(15), b int)")
+	for i := 1; i <= 100; i++ {
+		tk.MustExec("insert into t(b) values (?)", i)
+		tk.MustExec("insert into t(a, b) values (?, ?)", -i, i)
+	}
+	allHandles, err = ddltestutil.ExtractAllTableHandles(tk.Se, "test_auto_random_bits", "t")
+	c.Assert(err, IsNil)
+	// orderedHandles should be [-100, -99, ..., -2, -1, 1, 2, ..., 99, 100]
+	orderedHandles = testutil.ConfigTestUtils.MaskSortHandles(allHandles, 15, mysql.TypeLonglong)
+	size = int64(len(allHandles))
+	for i := int64(0); i < 100; i++ {
+		c.Assert(orderedHandles[i], Equals, i-100)
+	}
+	for i := int64(100); i < size; i++ {
+		c.Assert(orderedHandles[i], Equals, i-99)
+	}
+	tk.MustExec("drop table t")
 }
 
 func (s *testSuite6) TestMaxHandleAddIndex(c *C) {
diff --git a/executor/insert_common.go b/executor/insert_common.go
index aa0116e2f6c4d..f36347d2a5761 100644
--- a/executor/insert_common.go
+++ b/executor/insert_common.go
@@ -904,6 +904,9 @@ func (e *InsertValues) allocAutoRandomID(fieldType *types.FieldType) (int64, err
 }
 
 func (e *InsertValues) rebaseAutoRandomID(recordID int64, fieldType *types.FieldType) error {
+	if recordID < 0 {
+		return nil
+	}
 	alloc := e.Table.Allocators(e.ctx).Get(autoid.AutoRandomType)
 	tableInfo := e.Table.Meta()
 
diff --git a/util/testutil/testutil.go b/util/testutil/testutil.go
index 3ee8439248172..b36578e9dee19 100644
--- a/util/testutil/testutil.go
+++ b/util/testutil/testutil.go
@@ -342,7 +342,7 @@ func (a *autoRandom) RestoreAutoRandomTestConfig() {
 	globalCfg.AlterPrimaryKey = a.originAlterPrimaryKey
 }
 
-// MaskSortHandles masks highest shard_bits numbers of table handles and sort it.
+// MaskSortHandles sorts the handles by lowest (fieldTypeBits - 1 - shardBitsCount) bits.
 func (a *autoRandom) MaskSortHandles(handles []int64, shardBitsCount int, fieldType byte) []int64 {
 	typeBitsLength := mysql.DefaultLengthOfMysqlTypes[fieldType] * 8
 	const signBitCount = 1