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*: fix transaction lazy initialization in pessimistic mode (#14446) #14474

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merged 3 commits into from
Jan 15, 2020
Merged

*: fix transaction lazy initialization in pessimistic mode (#14446) #14474

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d4eeff4
*: fix transaction lazy initialization in pessimistic mode
jackysp Jan 10, 2020
1663632
add a protection
jackysp Jan 10, 2020
ad4a4b7
Merge branch 'release-3.0' into release-3.0-562a448b7db7
sre-bot Jan 15, 2020
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8 changes: 7 additions & 1 deletion executor/adapter.go
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Original file line number Diff line number Diff line change
Expand Up @@ -433,13 +433,19 @@ func (a *ExecStmt) handleNoDelayExecutor(ctx context.Context, e Executor) (sqlex

func (a *ExecStmt) handlePessimisticDML(ctx context.Context, e Executor) error {
sctx := a.Ctx
txn, err := sctx.Txn(true)
// Do not active the transaction here.
// When autocommit = 0 and transaction in pessimistic mode,
// statements like set xxx = xxx; should not active the transaction.
txn, err := sctx.Txn(false)
if err != nil {
return err
}
txnCtx := sctx.GetSessionVars().TxnCtx
for {
_, err = a.handleNoDelayExecutor(ctx, e)
if !txn.Valid() {
return err
}
if err != nil {
// It is possible the DML has point get plan that locks the key.
e, err = a.handlePessimisticLockError(ctx, err)
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8 changes: 8 additions & 0 deletions session/session_test.go
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Expand Up @@ -377,9 +377,17 @@ func (s *testSessionSuite) TestAutocommit(c *C) {
// TestTxnLazyInitialize tests that when autocommit = 0, not all statement starts
// a new transaction.
func (s *testSessionSuite) TestTxnLazyInitialize(c *C) {
testTxnLazyInitialize(s, c, false)
testTxnLazyInitialize(s, c, true)
}

func testTxnLazyInitialize(s *testSessionSuite, c *C, isPessimistic bool) {
tk := testkit.NewTestKitWithInit(c, s.store)
tk.MustExec("drop table if exists t")
tk.MustExec("create table t (id int)")
if isPessimistic {
tk.MustExec("set tidb_txn_mode = 'pessimistic'")
}

tk.MustExec("set @@autocommit = 0")
txn, err := tk.Se.Txn(true)
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