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*: Check index number in txn #29453

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*: Check index number in txn #29453

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1f41bd3
fix admin test
ekexium Dec 1, 2021
c99a35f
fix gosec
ekexium Dec 1, 2021
92c91f0
satisfy gosec
ekexium Dec 2, 2021
98b9985
assert that the number of index insertions must be a multiple of row …
ekexium Nov 3, 2021
a448ac4
assert that the number of index insertions must be a multiple of row …
ekexium Nov 3, 2021
e5545a0
count for each table
ekexium Nov 4, 2021
571a488
comment CheckTxnConsistency
ekexium Nov 4, 2021
b985104
only check when InTxn is true
ekexium Nov 4, 2021
5cb41f9
add ErrIncorrectIndexCount
ekexium Dec 6, 2021
d829187
Merge branch 'ft-data-inconsistency' into check-in-txn
ekexium Dec 7, 2021
995a8e2
only apply for certain SQLs
ekexium Dec 8, 2021
909a7aa
update enablement rule: use
ekexium Dec 9, 2021
9e58e0b
fix a error message and a test
ekexium Dec 10, 2021
bc408fd
address comments
ekexium Dec 15, 2021
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1 change: 1 addition & 0 deletions errno/errcode.go
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Original file line number Diff line number Diff line change
Expand Up @@ -1011,6 +1011,7 @@ const (
ErrAsOf = 8135
ErrVariableNoLongerSupported = 8136
ErrAnalyzeMissColumn = 8137
ErrIncorrectIndexCount = 8140

// Error codes used by TiDB ddl package
ErrUnsupportedDDLOperation = 8200
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1 change: 1 addition & 0 deletions errno/errname.go
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Expand Up @@ -1009,6 +1009,7 @@ var MySQLErrName = map[uint16]*mysql.ErrMessage{
ErrInvalidIncrementAndOffset: mysql.Message("Invalid auto_increment settings: auto_increment_increment: %d, auto_increment_offset: %d, both of them must be in range [1..65535]", nil),
ErrDataInconsistentMismatchCount: mysql.Message("data inconsistency in table: %s, index: %s, index-count:%d != record-count:%d", nil),
ErrDataInconsistentMismatchIndex: mysql.Message("data inconsistency in table: %s, index: %s, col: %s, handle: %#v, index-values:%#v != record-values:%#v, compare err:%#v", []int{3, 4, 5, 6}),
ErrIncorrectIndexCount: mysql.Message("incorrect index count in txn, row insertions: %d, index insertions: %d", nil),

ErrWarnOptimizerHintInvalidInteger: mysql.Message("integer value is out of range in '%s'", nil),
ErrWarnOptimizerHintUnsupportedHint: mysql.Message("Optimizer hint %s is not supported by TiDB and is ignored", nil),
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5 changes: 5 additions & 0 deletions errors.toml
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Expand Up @@ -1801,6 +1801,11 @@ error = '''
column %s can't be in none state
'''

["table:8140"]
error = '''
incorrect index count in txn, row insertions: %d, index insertions: %d
'''

["tikv:1105"]
error = '''
Unknown error
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11 changes: 11 additions & 0 deletions session/session.go
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Original file line number Diff line number Diff line change
Expand Up @@ -74,6 +74,7 @@ import (
"github.com/pingcap/tidb/statistics"
"github.com/pingcap/tidb/statistics/handle"
storeerr "github.com/pingcap/tidb/store/driver/error"
"github.com/pingcap/tidb/table/tables"
"github.com/pingcap/tidb/tablecodec"
"github.com/pingcap/tidb/telemetry"
"github.com/pingcap/tidb/types"
Expand Down Expand Up @@ -564,6 +565,16 @@ func (s *session) doCommit(ctx context.Context) error {

func (s *session) commitTxnWithTemporaryData(ctx context.Context, txn kv.Transaction) error {
sessVars := s.sessionVars

// Note: ignore auto-commit transactions because auto-commit transactions don't write untouched index mutations
// into the mem buffer, which invalidates the check.
// Only applies to user DML transactions.
if sessVars.ConnectionID != 0 && sessVars.EnableMutationChecker && sessVars.TxnCtx.IsExplicit {
if err := tables.CheckTxnConsistency(txn); err != nil {
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return errors.Trace(err)
}
}

txnTempTables := sessVars.TxnCtx.TemporaryTables
if len(txnTempTables) == 0 {
return txn.Commit(ctx)
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38 changes: 38 additions & 0 deletions table/tables/mutation_checker.go
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Expand Up @@ -18,18 +18,23 @@ import (
"fmt"

"github.com/pingcap/errors"
"github.com/pingcap/tidb/errno"
"github.com/pingcap/tidb/kv"
"github.com/pingcap/tidb/parser/model"
"github.com/pingcap/tidb/sessionctx/stmtctx"
"github.com/pingcap/tidb/sessionctx/variable"
"github.com/pingcap/tidb/table"
"github.com/pingcap/tidb/tablecodec"
"github.com/pingcap/tidb/types"
"github.com/pingcap/tidb/util/dbterror"
"github.com/pingcap/tidb/util/logutil"
"github.com/pingcap/tidb/util/rowcodec"
"go.uber.org/zap"
)

// ErrIncorrectIndexCount indicates that #(index_insertion) is not a multiple of #(row_insertion).
var ErrIncorrectIndexCount = dbterror.ClassTable.NewStd(errno.ErrIncorrectIndexCount)

type mutation struct {
key kv.Key
flags kv.KeyFlags
Expand Down Expand Up @@ -375,3 +380,36 @@ func getOrBuildColumnMaps(
}
return maps
}

// CheckTxnConsistency checks the number of row/index mutations before the txn commits,
// to prevent some inconsistent transactions.
func CheckTxnConsistency(txn kv.Transaction) error {
memBuffer := txn.GetMemBuffer()
if memBuffer == nil {
return nil
}

// count for each table
indexInsertionCount := make(map[int64]int)
rowInsertionCount := make(map[int64]int)
f := func(k kv.Key, v []byte) error {
if len(v) > 0 {
tableID := tablecodec.DecodeTableID(k)
if rowcodec.IsRowKey(k) {
rowInsertionCount[tableID] += 1
} else {
indexInsertionCount[tableID] += 1
}
}
return nil
}
if err := kv.WalkMemBuffer(memBuffer, f); err != nil {
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Does it process entries that's not modified but pessimistic-locked? Can it work with this change?

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@cfzjywxk cfzjywxk Dec 15, 2021 •
edited
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Yes it will process the locked but not changed keys, as each unique index key used to fetch rowkey will be turned into a PUT record, seems they are not compatibe, consider this:

create table t1(c1 int key, c2 int, c3 int, unique key uk(c2), key k1(c3));
insert into t1 values(1, 1, 1),(2, 2, 2),(3, 3, 3);
update t1 set c3 = c3 + 1 where c1 in (2, 3); // Use the batch point get executor.
here the to be committed keys are:
PUT uk 1->1 uk 2->2 uk 3->3
PUT sk  3_2 -> 2
PUT sk  4_3 -> 3
DEL sk   3_3 -> 3
DEL sk   2_2  -> 2
PUT rowkey  3-> 3, 3, 4
PUT rowkey  2-> 2, 2, 3

The number of PUT on row is 2 and the number of PUT on index is 5？

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@ekexium
Seems @MyonKeminta has found a key point.

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@ekexium ekexium Dec 15, 2021 •
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Right.. it's an intentional special case. It seems to me we can't simply tell whether it comes from the optimization. A workaround might be adding a flag to indicate the special usage so they can be ignored in the check.

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The change is actually not expected and it's a temoprary solution to workaround the performance issues with many LOCK records in the write cf. Maybe we could put back this check after solving the LOCK record issue so that these tricky optimization or transformation could be removed.

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I'm thinking if there is a method to distinguish the usage and won't block removing it.

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If we have to add some new flags to membuffer to handle this, I would suspect whether it worths...

return errors.Trace(err)
}
for tableID, count := range indexInsertionCount {
if rowInsertionCount[tableID] > 0 && count%rowInsertionCount[tableID] != 0 {
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We could add some comments to explain the proof or invariant here.

return ErrIncorrectIndexCount.GenWithStackByArgs(rowInsertionCount[tableID], count)
}
}
return nil
}
1 change: 1 addition & 0 deletions util/admin/admin_integration_test.go
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Expand Up @@ -121,6 +121,7 @@ func TestAdminCheckTableCorrupted(t *testing.T) {
store, clean := testkit.CreateMockStore(t)
defer clean()
tk := testkit.NewTestKit(t, store)
tk.MustExec("set @@tidb_enable_mutation_checker = 0;")
tk.MustExec("use test")
tk.MustExec("drop table if exists t")
tk.MustExec("create table t(id int, v int, UNIQUE KEY i1(id, v))")
Expand Down