ddl: add table option pre_split_regions for pre-split region when cre…

…ate table with shard_row_id_bits. (#10138)

ddl/ddl_api.go

@@ -1202,6 +1202,14 @@ func (d *ddl) CreateTable(ctx sessionctx.Context, s *ast.CreateTableStmt) (err e
 
 	err = d.doDDLJob(ctx, job)
 	if err == nil {
+		// do pre-split and scatter.
+		if tbInfo.ShardRowIDBits > 0 && tbInfo.PreSplitRegions > 0 {
+			if ctx.GetSessionVars().WaitTableSplitFinish {
+				preSplitTableRegion(d.store, tbInfo, true)
+			} else {
+				go preSplitTableRegion(d.store, tbInfo, false)
+			}
+		}
 		if tbInfo.AutoIncID > 1 {
 			// Default tableAutoIncID base is 0.
 			// If the first ID is expected to greater than 1, we need to do rebase.
@@ -1574,8 +1582,13 @@ func handleTableOptions(options []*ast.TableOption, tbInfo *model.TableInfo) err
 				tbInfo.ShardRowIDBits = shardRowIDBitsMax
 			}
 			tbInfo.MaxShardRowIDBits = tbInfo.ShardRowIDBits
+		case ast.TableOptionPreSplitRegion:
+			tbInfo.PreSplitRegions = op.UintValue
 		}
 	}
+	if tbInfo.PreSplitRegions > tbInfo.ShardRowIDBits {
+		tbInfo.PreSplitRegions = tbInfo.ShardRowIDBits
+	}
 
 	return nil
 }

ddl/table.go

@@ -336,6 +336,8 @@ func checkSafePoint(w *worker, snapshotTS uint64) error {
 
 type splitableStore interface {
 	SplitRegion(splitKey kv.Key) error
+	SplitRegionAndScatter(splitKey kv.Key) (uint64, error)
+	WaitScatterRegionFinish(regionID uint64) error
 }
 
 func splitTableRegion(store kv.Storage, tableID int64) {
@@ -350,6 +352,74 @@ func splitTableRegion(store kv.Storage, tableID int64) {
 	}
 }
 
+func preSplitTableRegion(store kv.Storage, tblInfo *model.TableInfo, waitTableSplitFinish bool) {
+	s, ok := store.(splitableStore)
+	if !ok {
+		return
+	}
+	regionIDs := make([]uint64, 0, 1<<(tblInfo.PreSplitRegions-1)+len(tblInfo.Indices))
+
+	// Example:
+	// ShardRowIDBits = 5
+	// PreSplitRegions = 3
+	//
+	// then will pre-split 2^(3-1) = 4 regions.
+	//
+	// in this code:
+	// max   = 1 << (tblInfo.ShardRowIDBits - 1) = 1 << (5-1) = 16
+	// step := int64(1 << (tblInfo.ShardRowIDBits - tblInfo.PreSplitRegions)) = 1 << (5-3) = 4;
+	//
+	// then split regionID is below:
+	// 4  << 59 = 2305843009213693952
+	// 8  << 59 = 4611686018427387904
+	// 12 << 59 = 6917529027641081856
+	//
+	// The 4 pre-split regions range is below:
+	// 0                   ~ 2305843009213693952
+	// 2305843009213693952 ~ 4611686018427387904
+	// 4611686018427387904 ~ 6917529027641081856
+	// 6917529027641081856 ~ 9223372036854775807 ( (1 << 63) - 1 )
+	//
+	// And the max _tidb_rowid is 9223372036854775807, it won't be negative number.
+
+	// Split table region.
+	step := int64(1 << (tblInfo.ShardRowIDBits - tblInfo.PreSplitRegions))
+	// The highest bit is the symbol bit,and alloc _tidb_rowid will always be positive number.
+	// So we only need to split the region for the positive number.
+	max := int64(1 << (tblInfo.ShardRowIDBits - 1))
+	for p := int64(step); p < max; p += step {
+		recordID := p << (64 - tblInfo.ShardRowIDBits)
+		recordPrefix := tablecodec.GenTableRecordPrefix(tblInfo.ID)
+		key := tablecodec.EncodeRecordKey(recordPrefix, recordID)
+		regionID, err := s.SplitRegionAndScatter(key)
+		if err != nil {
+			logutil.Logger(ddlLogCtx).Warn("[ddl] pre split table region failed", zap.Int64("recordID", recordID), zap.Error(err))
+		} else {
+			regionIDs = append(regionIDs, regionID)
+		}
+	}
+
+	// Split index region.
+	for _, idx := range tblInfo.Indices {
+		indexPrefix := tablecodec.EncodeTableIndexPrefix(tblInfo.ID, idx.ID)
+		regionID, err := s.SplitRegionAndScatter(indexPrefix)
+		if err != nil {
+			logutil.Logger(ddlLogCtx).Warn("[ddl] pre split table index region failed", zap.String("index", idx.Name.L), zap.Error(err))
+		} else {
+			regionIDs = append(regionIDs, regionID)
+		}
+	}
+	if !waitTableSplitFinish {
+		return
+	}
+	for _, regionID := range regionIDs {
+		err := s.WaitScatterRegionFinish(regionID)
+		if err != nil {
+			logutil.Logger(ddlLogCtx).Warn("[ddl] wait scatter region failed", zap.Uint64("regionID", regionID), zap.Error(err))
+		}
+	}
+}
+
 func getTable(store kv.Storage, schemaID int64, tblInfo *model.TableInfo) (table.Table, error) {
 	alloc := autoid.NewAllocator(store, tblInfo.GetDBID(schemaID), tblInfo.IsAutoIncColUnsigned())
 	tbl, err := table.TableFromMeta(alloc, tblInfo)

executor/set_test.go

@@ -339,6 +339,13 @@ func (s *testSuite2) TestSetVar(c *C) {
 	tk.MustQuery("select @@global.read_only;").Check(testkit.Rows("1"))
 	_, err = tk.Exec("set global read_only = abc")
 	c.Assert(err, NotNil)
+
+	// test for tidb_wait_table_split_finish
+	tk.MustQuery(`select @@session.tidb_wait_table_split_finish;`).Check(testkit.Rows("0"))
+	tk.MustExec("set tidb_wait_table_split_finish = 1")
+	tk.MustQuery(`select @@session.tidb_wait_table_split_finish;`).Check(testkit.Rows("1"))
+	tk.MustExec("set tidb_wait_table_split_finish = 0")
+	tk.MustQuery(`select @@session.tidb_wait_table_split_finish;`).Check(testkit.Rows("0"))
 }
 
 func (s *testSuite2) TestSetCharset(c *C) {

executor/show.go

@@ -791,7 +791,11 @@ func (e *ShowExec) fetchShowCreateTable() error {
 	}
 
 	if tb.Meta().ShardRowIDBits > 0 {
-		fmt.Fprintf(&buf, "/*!90000 SHARD_ROW_ID_BITS=%d */", tb.Meta().ShardRowIDBits)
+		fmt.Fprintf(&buf, "/*!90000 SHARD_ROW_ID_BITS=%d ", tb.Meta().ShardRowIDBits)
+		if tb.Meta().PreSplitRegions > 0 {
+			fmt.Fprintf(&buf, "PRE_SPLIT_REGIONS=%d ", tb.Meta().PreSplitRegions)
+		}
+		buf.WriteString("*/")
 	}
 
 	if len(tb.Meta().Comment) > 0 {

executor/show_test.go

@@ -445,6 +445,16 @@ func (s *testSuite2) TestShowCreateTable(c *C) {
 			"  `ch2` varbinary(10) DEFAULT NULL\n"+
 			") ENGINE=InnoDB DEFAULT CHARSET=utf8mb4 COLLATE=utf8mb4_bin",
 	))
+
+	tk.MustExec("create table t (a int, b int) shard_row_id_bits = 4 pre_split_regions=3;")
+	tk.MustQuery("show create table `t`").Check(testutil.RowsWithSep("|",
+		""+
+			"t CREATE TABLE `t` (\n"+
+			"  `a` int(11) DEFAULT NULL,\n"+
+			"  `b` int(11) DEFAULT NULL\n"+
+			") ENGINE=InnoDB DEFAULT CHARSET=utf8mb4 COLLATE=utf8mb4_bin/*!90000 SHARD_ROW_ID_BITS=4 PRE_SPLIT_REGIONS=3 */",
+	))
+	tk.MustExec("drop table t")
 }
 
 func (s *testSuite2) TestShowEscape(c *C) {

go.mod

@@ -3,38 +3,27 @@ module github.com/pingcap/tidb
 require (
 	github.com/BurntSushi/toml v0.3.1
 	github.com/StackExchange/wmi v0.0.0-20180725035823-b12b22c5341f // indirect
-	github.com/beorn7/perks v0.0.0-20180321164747-3a771d992973 // indirect
 	github.com/blacktear23/go-proxyprotocol v0.0.0-20180807104634-af7a81e8dd0d
 	github.com/boltdb/bolt v1.3.1 // indirect
 	github.com/codahale/hdrhistogram v0.0.0-20161010025455-3a0bb77429bd // indirect
 	github.com/coreos/bbolt v1.3.0 // indirect
-	github.com/coreos/etcd v3.3.10+incompatible
-	github.com/coreos/go-semver v0.2.0 // indirect
+	github.com/coreos/etcd v3.3.12+incompatible
 	github.com/coreos/go-systemd v0.0.0-20181031085051-9002847aa142 // indirect
 	github.com/coreos/pkg v0.0.0-20180928190104-399ea9e2e55f // indirect
 	github.com/cznic/mathutil v0.0.0-20181122101859-297441e03548
 	github.com/cznic/sortutil v0.0.0-20150617083342-4c7342852e65
-	github.com/dgrijalva/jwt-go v3.2.0+incompatible // indirect
 	github.com/dustin/go-humanize v1.0.0 // indirect
-	github.com/eknkc/amber v0.0.0-20171010120322-cdade1c07385 // indirect
-	github.com/etcd-io/gofail v0.0.0-20180808172546-51ce9a71510a // indirect
-	github.com/ghodss/yaml v1.0.0 // indirect
 	github.com/go-ole/go-ole v1.2.1 // indirect
 	github.com/go-sql-driver/mysql v0.0.0-20170715192408-3955978caca4
 	github.com/gogo/protobuf v1.2.0 // indirect
-	github.com/golang/groupcache v0.0.0-20181024230925-c65c006176ff // indirect
 	github.com/golang/protobuf v1.2.0
-	github.com/golang/snappy v0.0.0-20180518054509-2e65f85255db // indirect
 	github.com/google/btree v0.0.0-20180813153112-4030bb1f1f0c
 	github.com/gorilla/context v1.1.1 // indirect
 	github.com/gorilla/mux v1.6.2
 	github.com/gorilla/websocket v1.4.0 // indirect
-	github.com/grpc-ecosystem/go-grpc-middleware v1.0.0
-	github.com/grpc-ecosystem/go-grpc-prometheus v1.2.0 // indirect
+	github.com/grpc-ecosystem/go-grpc-middleware v1.0.1-0.20190118093823-f849b5445de4
 	github.com/grpc-ecosystem/grpc-gateway v1.5.1 // indirect
-	github.com/jonboulle/clockwork v0.1.0 // indirect
 	github.com/klauspost/cpuid v0.0.0-20170728055534-ae7887de9fa5
-	github.com/mailru/easyjson v0.0.0-20190312143242-1de009706dbe // indirect
 	github.com/matttproud/golang_protobuf_extensions v1.0.1 // indirect
 	github.com/montanaflynn/stats v0.0.0-20180911141734-db72e6cae808 // indirect
 	github.com/myesui/uuid v1.0.0 // indirect
@@ -44,18 +33,16 @@ require (
 	github.com/onsi/gomega v1.4.3 // indirect
 	github.com/opentracing/basictracer-go v1.0.0
 	github.com/opentracing/opentracing-go v1.0.2
-	github.com/philhofer/fwd v1.0.0 // indirect
 	github.com/pingcap/check v0.0.0-20190102082844-67f458068fc8
 	github.com/pingcap/errors v0.11.1
 	github.com/pingcap/failpoint v0.0.0-20190422094118-d8535965f59b
 	github.com/pingcap/goleveldb v0.0.0-20171020122428-b9ff6c35079e
-	github.com/pingcap/kvproto v0.0.0-20190215154024-7f2fc73ef562
+	github.com/pingcap/kvproto v0.0.0-20190327032727-3d8cb3a30d5d
 	github.com/pingcap/log v0.0.0-20190307075452-bd41d9273596
 	github.com/pingcap/parser v0.0.0-20190424024541-e2cdb851bce2
-	github.com/pingcap/pd v2.1.0-rc.4+incompatible
+	github.com/pingcap/pd v0.0.0-20190424024702-bd1e2496a669
 	github.com/pingcap/tidb-tools v2.1.3-0.20190321065848-1e8b48f5c168+incompatible
 	github.com/pingcap/tipb v0.0.0-20190107072121-abbec73437b7
-	github.com/pquerna/ffjson v0.0.0-20181028064349-e517b90714f7 // indirect
 	github.com/prometheus/client_golang v0.9.0
 	github.com/prometheus/client_model v0.0.0-20180712105110-5c3871d89910
 	github.com/prometheus/common v0.0.0-20181020173914-7e9e6cabbd39 // indirect
@@ -65,19 +52,14 @@ require (
 	github.com/shurcooL/httpfs v0.0.0-20171119174359-809beceb2371 // indirect
 	github.com/shurcooL/vfsgen v0.0.0-20181020040650-a97a25d856ca // indirect
 	github.com/sirupsen/logrus v1.2.0
-	github.com/soheilhy/cmux v0.1.4 // indirect
 	github.com/spaolacci/murmur3 v0.0.0-20180118202830-f09979ecbc72
 	github.com/struCoder/pidusage v0.1.2
 	github.com/tiancaiamao/appdash v0.0.0-20181126055449-889f96f722a2
-	github.com/tinylib/msgp v1.1.0 // indirect
-	github.com/tmc/grpc-websocket-proxy v0.0.0-20171017195756-830351dc03c6 // indirect
 	github.com/twinj/uuid v1.0.0
 	github.com/uber-go/atomic v1.3.2 // indirect
 	github.com/uber/jaeger-client-go v2.15.0+incompatible
 	github.com/uber/jaeger-lib v1.5.0 // indirect
-	github.com/ugorji/go v0.0.0-20171019201919-bdcc60b419d1 // indirect
 	github.com/unrolled/render v0.0.0-20180914162206-b9786414de4d // indirect
-	github.com/xiang90/probing v0.0.0-20160813154853-07dd2e8dfe18 // indirect
 	go.uber.org/zap v1.9.1
 	golang.org/x/net v0.0.0-20190108225652-1e06a53dbb7e
 	golang.org/x/sys v0.0.0-20190109145017-48ac38b7c8cb // indirect