expression: add builtin function tidb_decode_key()

expression/builtin.go

@@ -719,4 +719,7 @@ var funcs = map[string]functionClass{
 	ast.JSONDepth:         &jsonDepthFunctionClass{baseFunctionClass{ast.JSONDepth, 1, 1}},
 	ast.JSONKeys:          &jsonKeysFunctionClass{baseFunctionClass{ast.JSONKeys, 1, 2}},
 	ast.JSONLength:        &jsonLengthFunctionClass{baseFunctionClass{ast.JSONLength, 1, 2}},
+
+	// TiDB internal function.
+	ast.TiDBDecodeKey: &tidbDecodeKeyFunctionClass{baseFunctionClass{ast.TiDBDecodeKey, 1, 1}},
 }

expression/builtin_info.go

@@ -18,13 +18,18 @@
 package expression
 
 import (
+	"encoding/hex"
+	"fmt"
 	"sort"
+	"strconv"
 
 	"github.com/pingcap/errors"
 	"github.com/pingcap/parser/mysql"
 	"github.com/pingcap/tidb/sessionctx"
+	"github.com/pingcap/tidb/tablecodec"
 	"github.com/pingcap/tidb/types"
 	"github.com/pingcap/tidb/util/chunk"
+	"github.com/pingcap/tidb/util/codec"
 	"github.com/pingcap/tidb/util/printer"
 )
 
@@ -44,6 +49,7 @@ var (
 	_ functionClass = &rowCountFunctionClass{}
 	_ functionClass = &tidbVersionFunctionClass{}
 	_ functionClass = &tidbIsDDLOwnerFunctionClass{}
+	_ functionClass = &tidbDecodeKeyFunctionClass{}
 )
 
 var (
@@ -57,6 +63,7 @@ var (
 	_ builtinFunc = &builtinVersionSig{}
 	_ builtinFunc = &builtinTiDBVersionSig{}
 	_ builtinFunc = &builtinRowCountSig{}
+	_ builtinFunc = &builtinTiDBDecodeKeySig{}
 )
 
 type databaseFunctionClass struct {
@@ -589,3 +596,63 @@ func (b *builtinRowCountSig) evalInt(_ chunk.Row) (res int64, isNull bool, err e
 	res = int64(b.ctx.GetSessionVars().StmtCtx.PrevAffectedRows)
 	return res, false, nil
 }
+
+type tidbDecodeKeyFunctionClass struct {
+	baseFunctionClass
+}
+
+func (c *tidbDecodeKeyFunctionClass) getFunction(ctx sessionctx.Context, args []Expression) (builtinFunc, error) {
+	if err := c.verifyArgs(args); err != nil {
+		return nil, err
+	}
+	bf := newBaseBuiltinFuncWithTp(ctx, args, types.ETString, types.ETString)
+	sig := &builtinTiDBDecodeKeySig{bf}
+	return sig, nil
+}
+
+type builtinTiDBDecodeKeySig struct {
+	baseBuiltinFunc
+}
+
+func (b *builtinTiDBDecodeKeySig) Clone() builtinFunc {
+	newSig := &builtinTiDBDecodeKeySig{}
+	newSig.cloneFrom(&b.baseBuiltinFunc)
+	return newSig
+}
+
+// evalInt evals a builtinTiDBIsDDLOwnerSig.
+func (b *builtinTiDBDecodeKeySig) evalString(row chunk.Row) (string, bool, error) {
+	s, isNull, err := b.args[0].EvalString(b.ctx, row)
+	if isNull || err != nil {
+		return "", isNull, err
+	}
+	return decodeKey(b.ctx, s), false, nil
+}
+
+func decodeKey(ctx sessionctx.Context, s string) string {
+	key, err := hex.DecodeString(s)
+	if err != nil {
+		ctx.GetSessionVars().StmtCtx.AppendWarning(errors.Errorf("invalid record/index key: %v", key))
+		return s
+	}
+	// Auto decode byte if needed.
+	_, bs, err := codec.DecodeBytes([]byte(key), nil)
+	if err == nil {
+		key = bs
+	}
+	// Try to decode it as a record key.
+	tableID, handle, err := tablecodec.DecodeRecordKey(key)
+	if err == nil {
+		return "tableID=" + strconv.FormatInt(tableID, 10) + ", _tidb_rowid=" + strconv.FormatInt(handle, 10)
+	}
+	// Try decode as table index key.
+	tableID, indexID, indexValues, err := tablecodec.DecodeIndexKeyPrefix(key)
+	if err == nil {
+		idxValueStr := fmt.Sprintf("%X", indexValues)
+		return "tableID=" + strconv.FormatInt(tableID, 10) + ", indexID=" + strconv.FormatInt(indexID, 10) + ", indexValues=" + idxValueStr
+	}
+
+	// TODO: try to decode other type key.
+	ctx.GetSessionVars().StmtCtx.AppendWarning(errors.New("the key is a invalid record/index key"))
+	return s
+}

expression/integration_test.go

@@ -4123,6 +4123,23 @@ func (s *testIntegrationSuite) testTiDBIsOwnerFunc(c *C) {
 	result.Check(testkit.Rows(fmt.Sprintf("%v", ret)))
 }
 
+func (s *testIntegrationSuite) TestTiDBInternalFunc(c *C) {
+	tk := testkit.NewTestKit(c, s.store)
+	defer s.cleanEnv(c)
+	result := tk.MustQuery("select tidb_decode_key( '74800000000000002B5F72800000000000A5D3' )")
+	result.Check(testkit.Rows("tableID=43, _tidb_rowid=42451"))
+
+	result = tk.MustQuery("select tidb_decode_key( '74800000000000019B5F698000000000000001015257303100000000FB013736383232313130FF3900000000000000F8010000000000000000F7' )")
+	result.Check(testkit.Rows("tableID=411, indexID=1, indexValues=015257303100000000FB013736383232313130FF3900000000000000F8010000000000000000F7"))
+
+	// Test invalid record/index key.
+	result = tk.MustQuery("select tidb_decode_key( '7480000000000000FF2E5F728000000011FFE1A3000000000000' )")
+	result.Check(testkit.Rows("7480000000000000FF2E5F728000000011FFE1A3000000000000"))
+	warns := tk.Se.GetSessionVars().StmtCtx.GetWarnings()
+	c.Assert(warns, HasLen, 1)
+	c.Assert(warns[0].Err.Error(), Equals, "the key is a invalid record/index key")
+}
+
 func newStoreWithBootstrap() (kv.Storage, *domain.Domain, error) {
 	store, err := mockstore.NewMockTikvStore()
 	if err != nil {

go.mod

@@ -41,7 +41,7 @@ require (
 	github.com/pingcap/goleveldb v0.0.0-20171020122428-b9ff6c35079e
 	github.com/pingcap/kvproto v0.0.0-20190910074005-0e61b6f435c1
 	github.com/pingcap/log v0.0.0-20190715063458-479153f07ebd
-	github.com/pingcap/parser v0.0.0-20190912032624-978b8272c04e
+	github.com/pingcap/parser v0.0.0-20190923031704-33636bc5e5d6
 	github.com/pingcap/pd v0.0.0-20190712044914-75a1f9f3062b
 	github.com/pingcap/tidb-tools v2.1.3-0.20190321065848-1e8b48f5c168+incompatible
 	github.com/pingcap/tipb v0.0.0-20190806070524-16909e03435e

go.sum

@@ -166,8 +166,8 @@ github.com/pingcap/kvproto v0.0.0-20190910074005-0e61b6f435c1/go.mod h1:QMdbTAXC
 github.com/pingcap/log v0.0.0-20190214045112-b37da76f67a7/go.mod h1:xsfkWVaFVV5B8e1K9seWfyJWFrIhbtUTAD8NV1Pq3+w=
 github.com/pingcap/log v0.0.0-20190715063458-479153f07ebd h1:hWDol43WY5PGhsh3+8794bFHY1bPrmu6bTalpssCrGg=
 github.com/pingcap/log v0.0.0-20190715063458-479153f07ebd/go.mod h1:WpHUKhNZ18v116SvGrmjkA9CBhYmuUTKL+p8JC9ANEw=
-github.com/pingcap/parser v0.0.0-20190912032624-978b8272c04e h1:QeD1wC7bGElAhufSHH4JcIbs1cVdxnGWD3n3gcE5qeY=
-github.com/pingcap/parser v0.0.0-20190912032624-978b8272c04e/go.mod h1:1FNvfp9+J0wvc4kl8eGNh7Rqrxveg15jJoWo/a0uHwA=
+github.com/pingcap/parser v0.0.0-20190923031704-33636bc5e5d6 h1:PyjsTUD8gJ6QGilbwiy/TTn89J84/69Pj9LixOd/fFE=
+github.com/pingcap/parser v0.0.0-20190923031704-33636bc5e5d6/go.mod h1:1FNvfp9+J0wvc4kl8eGNh7Rqrxveg15jJoWo/a0uHwA=
 github.com/pingcap/pd v0.0.0-20190712044914-75a1f9f3062b h1:oS9PftxQqgcRouKhhdaB52tXhVLEP7Ng3Qqsd6Z18iY=
 github.com/pingcap/pd v0.0.0-20190712044914-75a1f9f3062b/go.mod h1:3DlDlFT7EF64A1bmb/tulZb6wbPSagm5G4p1AlhaEDs=
 github.com/pingcap/tidb-tools v2.1.3-0.20190321065848-1e8b48f5c168+incompatible h1:MkWCxgZpJBgY2f4HtwWMMFzSBb3+JPzeJgF3VrXE/bU=

tablecodec/tablecodec.go

@@ -127,14 +127,10 @@ func DecodeRecordKey(key kv.Key) (tableID int64, handle int64, err error) {
 func DecodeIndexKey(key kv.Key) (tableID int64, indexID int64, indexValues []string, err error) {
 	k := key
 
-	tableID, indexID, isRecord, err := DecodeKeyHead(key)
+	tableID, indexID, key, err = DecodeIndexKeyPrefix(key)
 	if err != nil {
 		return 0, 0, nil, errors.Trace(err)
 	}
-	if isRecord {
-		return 0, 0, nil, errInvalidIndexKey.GenWithStack("invalid index key - %q", k)
-	}
-	key = key[prefixLen+idLen:]
 
 	for len(key) > 0 {
 		// FIXME: Without the schema information, we can only decode the raw kind of
@@ -153,6 +149,22 @@ func DecodeIndexKey(key kv.Key) (tableID int64, indexID int64, indexValues []str
 	return
 }
 
+// DecodeIndexKeyPrefix decodes the key and gets the tableID, indexID, indexValues.
+func DecodeIndexKeyPrefix(key kv.Key) (tableID int64, indexID int64, indexValues []byte, err error) {
+	k := key
+
+	tableID, indexID, isRecord, err := DecodeKeyHead(key)
+	if err != nil {
+		return 0, 0, nil, errors.Trace(err)
+	}
+	if isRecord {
+		return 0, 0, nil, errInvalidIndexKey.GenWithStack("invalid index key - %q", k)
+	}
+	indexValues = key[prefixLen+idLen:]
+
+	return tableID, indexID, indexValues, nil
+}
+
 // DecodeKeyHead decodes the key's head and gets the tableID, indexID. isRecordKey is true when is a record key.
 func DecodeKeyHead(key kv.Key) (tableID int64, indexID int64, isRecordKey bool, err error) {
 	isRecordKey = false