From 8ca994818f0dae04d1a5180b53b9ca9977016a16 Mon Sep 17 00:00:00 2001
From: crazycs520 <crazycs520@gmail.com>
Date: Mon, 9 Sep 2019 10:47:26 +0800
Subject: [PATCH] config: add split-region-max-num in config to control the
 maximum split region number (#11427)

---
 config/config.go            | 4 +++-
 config/config.toml.example  | 3 +++
 config/config_test.go       | 2 ++
 planner/core/planbuilder.go | 5 +++--
 4 files changed, 11 insertions(+), 3 deletions(-)

diff --git a/config/config.go b/config/config.go
index 9235f753d5aa0..8aa5add1583a4 100644
--- a/config/config.go
+++ b/config/config.go
@@ -88,7 +88,8 @@ type Config struct {
 	CheckMb4ValueInUTF8 bool              `toml:"check-mb4-value-in-utf8" json:"check-mb4-value-in-utf8"`
 	// TreatOldVersionUTF8AsUTF8MB4 is use to treat old version table/column UTF8 charset as UTF8MB4. This is for compatibility.
 	// Currently not support dynamic modify, because this need to reload all old version schema.
-	TreatOldVersionUTF8AsUTF8MB4 bool `toml:"treat-old-version-utf8-as-utf8mb4" json:"treat-old-version-utf8-as-utf8mb4"`
+	TreatOldVersionUTF8AsUTF8MB4 bool   `toml:"treat-old-version-utf8-as-utf8mb4" json:"treat-old-version-utf8-as-utf8mb4"`
+	SplitRegionMaxNum            uint64 `toml:"split-region-max-num" json:"split-region-max-num"`
 }
 
 // Log is the log section of config.
@@ -321,6 +322,7 @@ var defaultConf = Config{
 	EnableStreaming:              false,
 	CheckMb4ValueInUTF8:          true,
 	TreatOldVersionUTF8AsUTF8MB4: true,
+	SplitRegionMaxNum:            1000,
 	TxnLocalLatches: TxnLocalLatches{
 		Enabled:  true,
 		Capacity: 2048000,
diff --git a/config/config.toml.example b/config/config.toml.example
index 93a5454196ed7..b2016f95d1e29 100644
--- a/config/config.toml.example
+++ b/config/config.toml.example
@@ -54,6 +54,9 @@ check-mb4-value-in-utf8 = true
 # treat-old-version-utf8-as-utf8mb4 use for upgrade compatibility. Set to true will treat old version table/column UTF8 charset as UTF8MB4.
 treat-old-version-utf8-as-utf8mb4 = true
 
+# Maximum number of the splitting region, which is used by the split region statement.
+split-region-max-num = 1000
+
 [log]
 # Log level: debug, info, warn, error, fatal.
 level = "info"
diff --git a/config/config_test.go b/config/config_test.go
index ddc18e2f6cc04..84d8788d66f9b 100644
--- a/config/config_test.go
+++ b/config/config_test.go
@@ -60,6 +60,7 @@ unrecognized-option-test = true
 
 	_, err = f.WriteString(`
 token-limit = 0
+split-region-max-num=10000
 [performance]
 [tikv-client]
 commit-timeout="41s"
@@ -78,6 +79,7 @@ max-batch-size=128
 	c.Assert(conf.TiKVClient.CommitTimeout, Equals, "41s")
 	c.Assert(conf.TiKVClient.MaxBatchSize, Equals, uint(128))
 	c.Assert(conf.TokenLimit, Equals, uint(1000))
+	c.Assert(conf.SplitRegionMaxNum, Equals, uint64(10000))
 	c.Assert(f.Close(), IsNil)
 	c.Assert(os.Remove(configFile), IsNil)
 
diff --git a/planner/core/planbuilder.go b/planner/core/planbuilder.go
index a2a717d694636..86a6ffe381d71 100644
--- a/planner/core/planbuilder.go
+++ b/planner/core/planbuilder.go
@@ -27,6 +27,7 @@ import (
 	"github.com/pingcap/parser/model"
 	"github.com/pingcap/parser/mysql"
 	"github.com/pingcap/parser/opcode"
+	"github.com/pingcap/tidb/config"
 	"github.com/pingcap/tidb/ddl"
 	"github.com/pingcap/tidb/expression"
 	"github.com/pingcap/tidb/infoschema"
@@ -1774,8 +1775,6 @@ func (b *PlanBuilder) buildLoadStats(ld *ast.LoadStatsStmt) Plan {
 	return p
 }
 
-const maxSplitRegionNum = 1000
-
 func (b *PlanBuilder) buildSplitRegion(node *ast.SplitRegionStmt) (Plan, error) {
 	if len(node.IndexName.L) != 0 {
 		return b.buildSplitIndexRegion(node)
@@ -1836,6 +1835,7 @@ func (b *PlanBuilder) buildSplitIndexRegion(node *ast.SplitRegionStmt) (Plan, er
 	p.Lower = lowerValues
 	p.Upper = upperValues
 
+	maxSplitRegionNum := int64(config.GetGlobalConfig().SplitRegionMaxNum)
 	if node.SplitOpt.Num > maxSplitRegionNum {
 		return nil, errors.Errorf("Split index region num exceeded the limit %v", maxSplitRegionNum)
 	} else if node.SplitOpt.Num < 1 {
@@ -1946,6 +1946,7 @@ func (b *PlanBuilder) buildSplitTableRegion(node *ast.SplitRegionStmt) (Plan, er
 	p.Lower = []types.Datum{lowerValues}
 	p.Upper = []types.Datum{upperValue}
 
+	maxSplitRegionNum := int64(config.GetGlobalConfig().SplitRegionMaxNum)
 	if node.SplitOpt.Num > maxSplitRegionNum {
 		return nil, errors.Errorf("Split table region num exceeded the limit %v", maxSplitRegionNum)
 	} else if node.SplitOpt.Num < 1 {