model(cdc): add a function to recover TiDB TableInfo (#7480)

ref #3242

cdc/entry/mounter_test.go

@@ -14,20 +14,27 @@
 package entry
 
 import (
+	"bytes"
 	"context"
 	"strings"
 	"testing"
 	"time"
 
 	"github.com/pingcap/log"
 	ticonfig "github.com/pingcap/tidb/config"
+	"github.com/pingcap/tidb/ddl"
+	"github.com/pingcap/tidb/executor"
 	tidbkv "github.com/pingcap/tidb/kv"
+	"github.com/pingcap/tidb/meta/autoid"
+	"github.com/pingcap/tidb/parser"
+	"github.com/pingcap/tidb/parser/ast"
 	timodel "github.com/pingcap/tidb/parser/model"
 	"github.com/pingcap/tidb/parser/mysql"
 	"github.com/pingcap/tidb/session"
 	"github.com/pingcap/tidb/store/mockstore"
 	"github.com/pingcap/tidb/testkit"
 	"github.com/pingcap/tidb/types"
+	"github.com/pingcap/tidb/util/mock"
 	"github.com/pingcap/tiflow/cdc/model"
 	"github.com/pingcap/tiflow/pkg/config"
 	pfilter "github.com/pingcap/tiflow/pkg/filter"
@@ -1087,3 +1094,72 @@ func TestDecodeEventIgnoreRow(t *testing.T) {
 		decodeAndCheckRowInTable(tableInfo.ID, toRawKV)
 	}
 }
+
+func TestBuildTableInfo(t *testing.T) {
+	cases := []struct {
+		origin    string
+		recovered string
+	}{
+		{
+			"CREATE TABLE t1 (c INT PRIMARY KEY)",
+			"CREATE TABLE `BuildTiDBTableInfo` (\n" +
+				"  `c` int(0) NOT NULL,\n" +
+				"  PRIMARY KEY (`c`(0)) /*T![clustered_index] CLUSTERED */\n" +
+				") ENGINE=InnoDB DEFAULT CHARSET=utf8mb4 COLLATE=utf8mb4_bin",
+		},
+		{
+			"CREATE TABLE t1 (" +
+				" c INT UNSIGNED," +
+				" c2 VARCHAR(10) NOT NULL," +
+				" c3 BIT(10) NOT NULL," +
+				" UNIQUE KEY (c2, c3)" +
+				")",
+			// CDC discards field length.
+			"CREATE TABLE `BuildTiDBTableInfo` (\n" +
+				"  `c` int(0) unsigned DEFAULT NULL,\n" +
+				"  `c2` varchar(0) NOT NULL,\n" +
+				"  `c3` bit(0) NOT NULL,\n" +
+				"  UNIQUE KEY `idx_0` (`c2`(0),`c3`(0))\n" +
+				") ENGINE=InnoDB DEFAULT CHARSET=utf8mb4 COLLATE=utf8mb4_bin",
+		},
+		{
+			"CREATE TABLE t1 (" +
+				" c INT UNSIGNED," +
+				" gen INT AS (c+1) VIRTUAL," +
+				" c2 VARCHAR(10) NOT NULL," +
+				" gen2 INT AS (c+2) STORED," +
+				" c3 BIT(10) NOT NULL," +
+				" PRIMARY KEY (c, c2)" +
+				")",
+			// CDC discards virtual generated column, and generating expression of stored generated column.
+			"CREATE TABLE `BuildTiDBTableInfo` (\n" +
+				"  `c` int(0) unsigned NOT NULL,\n" +
+				"  `c2` varchar(0) NOT NULL,\n" +
+				"  `gen2` int(0) GENERATED ALWAYS AS (pass_generated_check) STORED,\n" +
+				"  `c3` bit(0) NOT NULL,\n" +
+				"  PRIMARY KEY (`c`(0),`c2`(0)) /*T![clustered_index] CLUSTERED */\n" +
+				") ENGINE=InnoDB DEFAULT CHARSET=utf8mb4 COLLATE=utf8mb4_bin",
+		},
+	}
+	p := parser.New()
+	for _, c := range cases {
+		stmt, err := p.ParseOneStmt(c.origin, "", "")
+		require.NoError(t, err)
+		originTI, err := ddl.BuildTableInfoFromAST(stmt.(*ast.CreateTableStmt))
+		require.NoError(t, err)
+		cdcTableInfo := model.WrapTableInfo(0, "test", 0, originTI)
+		cols, _, err := datum2Column(cdcTableInfo, map[int64]types.Datum{}, true)
+		require.NoError(t, err)
+		recoveredTI := model.BuildTiDBTableInfo(cols, cdcTableInfo.IndexColumnsOffset)
+		require.Equal(t, c.recovered, showCreateTable(t, recoveredTI))
+	}
+}
+
+var tiCtx = mock.NewContext()
+
+func showCreateTable(t *testing.T, ti *timodel.TableInfo) string {
+	result := bytes.NewBuffer(make([]byte, 0, 512))
+	err := executor.ConstructResultOfShowCreateTable(tiCtx, ti, autoid.Allocators{}, result)
+	require.NoError(t, err)
+	return result.String()
+}

cdc/model/schema_storage.go

@@ -207,7 +207,7 @@ func (ti *TableInfo) initColumnsFlag() {
 	// See https://dev.mysql.com/doc/refman/5.7/en/show-columns.html.
 	// Yet if an index has multiple columns, we would like to easily determine that all those columns are indexed,
 	// which is crucial for the completeness of the information we pass to the downstream.
-	// Therefore, instead of using the MySql standard,
+	// Therefore, instead of using the MySQL standard,
 	// we made our own decision to mark all columns in an index with the appropriate flag(s).
 	for _, idxInfo := range ti.Indices {
 		for _, idxCol := range idxInfo.Columns {

cdc/model/sink.go

@@ -21,6 +21,7 @@ import (
 
 	"github.com/pingcap/log"
 	"github.com/pingcap/tidb/parser/model"
+	"github.com/pingcap/tidb/parser/mysql"
 	"github.com/pingcap/tidb/util/rowcodec"
 	"github.com/pingcap/tiflow/pkg/quotes"
 	"github.com/pingcap/tiflow/pkg/util"
@@ -442,6 +443,97 @@ type RedoColumn struct {
 	Flag   uint64  `msg:"flag"`
 }
 
+// BuildTiDBTableInfo builds a TiDB TableInfo from given information.
+func BuildTiDBTableInfo(columns []*Column, indexColumns [][]int) *model.TableInfo {
+	ret := &model.TableInfo{}
+	// nowhere will use this field, so we set a debug message
+	ret.Name = model.NewCIStr("BuildTiDBTableInfo")
+
+	for i, col := range columns {
+		columnInfo := &model.ColumnInfo{
+			Offset: i,
+			State:  model.StatePublic,
+		}
+		if col == nil {
+			// by referring to datum2Column, nil is happened when
+			// - !IsColCDCVisible, which means the column is a virtual generated
+			//   column
+			// - !exist && !fillWithDefaultValue, which means upstream does not
+			//   send the column value
+			// just mock for the first case
+			columnInfo.Name = model.NewCIStr("omitted")
+			columnInfo.GeneratedExprString = "pass_generated_check"
+			columnInfo.GeneratedStored = false
+			ret.Columns = append(ret.Columns, columnInfo)
+			continue
+		}
+		columnInfo.Name = model.NewCIStr(col.Name)
+		columnInfo.SetType(col.Type)
+		// TiKV always use utf8mb4 to store, and collation is not recorded by CDC
+		columnInfo.SetCharset(mysql.UTF8MB4Charset)
+		columnInfo.SetCollate(mysql.UTF8MB4DefaultCollation)
+
+		// inverse initColumnsFlag
+		flag := col.Flag
+		if flag.IsBinary() {
+			columnInfo.SetCharset("binary")
+		}
+		if flag.IsGeneratedColumn() {
+			// we do not use this field, so we set it to any non-empty string
+			columnInfo.GeneratedExprString = "pass_generated_check"
+			columnInfo.GeneratedStored = true
+		}
+		if flag.IsHandleKey() {
+			columnInfo.AddFlag(mysql.PriKeyFlag)
+			ret.IsCommonHandle = true
+		} else if flag.IsPrimaryKey() {
+			columnInfo.AddFlag(mysql.PriKeyFlag)
+		}
+		if flag.IsUniqueKey() {
+			columnInfo.AddFlag(mysql.UniqueKeyFlag)
+		}
+		if !flag.IsNullable() {
+			columnInfo.AddFlag(mysql.NotNullFlag)
+		}
+		if flag.IsMultipleKey() {
+			columnInfo.AddFlag(mysql.MultipleKeyFlag)
+		}
+		if flag.IsUnsigned() {
+			columnInfo.AddFlag(mysql.UnsignedFlag)
+		}
+		ret.Columns = append(ret.Columns, columnInfo)
+	}
+
+	for i, colOffsets := range indexColumns {
+		indexInfo := &model.IndexInfo{
+			Name:  model.NewCIStr(fmt.Sprintf("idx_%d", i)),
+			State: model.StatePublic,
+		}
+		firstCol := columns[colOffsets[0]]
+		if firstCol.Flag.IsPrimaryKey() {
+			indexInfo.Primary = true
+		}
+		if firstCol.Flag.IsUniqueKey() {
+			indexInfo.Unique = true
+		}
+
+		for _, offset := range colOffsets {
+			col := ret.Columns[offset]
+
+			indexCol := &model.IndexColumn{}
+			indexCol.Name = col.Name
+			indexCol.Offset = offset
+			indexInfo.Columns = append(indexInfo.Columns, indexCol)
+		}
+
+		// TODO: revert the "all column set index related flag" to "only the
+		// first column set index related flag" if needed
+
+		ret.Indices = append(ret.Indices, indexInfo)
+	}
+	return ret
+}
+
 // ColumnValueString returns the string representation of the column value
 func ColumnValueString(c interface{}) string {
 	var data string