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session: add a batch commit session variable for the large transaction #8293

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merged 16 commits into from
Dec 10, 2018
Merged

session: add a batch commit session variable for the large transaction #8293

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1b0d658
support batch commit for the TiDB server
jackysp Nov 13, 2018
46dcb7c
tiny fix
jackysp Nov 13, 2018
6c020f6
address comments
jackysp Nov 13, 2018
c326322
add test cases
jackysp Nov 15, 2018
740387d
tiny fix
jackysp Nov 15, 2018
fab5f83
Merge branch 'master' into batch_commit
jackysp Nov 16, 2018
16a645d
add one case
jackysp Nov 16, 2018
809dc75
Merge branch 'master' into batch_commit
jackysp Nov 27, 2018
8982dd2
move to a session var
jackysp Dec 3, 2018
dec9ba1
fix test
jackysp Dec 3, 2018
8cbcd37
fix CI
jackysp Dec 3, 2018
72c1139
add a set test
jackysp Dec 3, 2018
f06c961
Merge branch 'master' into batch_commit
lysu Dec 4, 2018
7982488
Merge branch 'master' into batch_commit
jackysp Dec 10, 2018
7ef4275
resolve conflicts
jackysp Dec 10, 2018
8128841
Merge branch 'master' into batch_commit
jackysp Dec 10, 2018
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2 changes: 2 additions & 0 deletions config/config.go
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Original file line number Diff line number Diff line change
Expand Up @@ -155,6 +155,7 @@ type Performance struct {
StatsLease string `toml:"stats-lease" json:"stats-lease"`
RunAutoAnalyze bool `toml:"run-auto-analyze" json:"run-auto-analyze"`
StmtCountLimit uint `toml:"stmt-count-limit" json:"stmt-count-limit"`
BatchCommit bool `toml:"batch-commit" json:"batch-commit"`
FeedbackProbability float64 `toml:"feedback-probability" json:"feedback-probability"`
QueryFeedbackLimit uint `toml:"query-feedback-limit" json:"query-feedback-limit"`
PseudoEstimateRatio float64 `toml:"pseudo-estimate-ratio" json:"pseudo-estimate-ratio"`
Expand Down Expand Up @@ -292,6 +293,7 @@ var defaultConf = Config{
StatsLease: "3s",
RunAutoAnalyze: true,
StmtCountLimit: 5000,
BatchCommit: false,
FeedbackProbability: 0.05,
QueryFeedbackLimit: 1024,
PseudoEstimateRatio: 0.8,
Expand Down
2 changes: 2 additions & 0 deletions config/config.toml.example
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Expand Up @@ -124,6 +124,8 @@ metrics-interval = 15
max-procs = 0
# StmtCountLimit limits the max count of statement inside a transaction.
stmt-count-limit = 5000
# If true, the transaction will be committed when it reaches stmt-count-limit and starts a new transaction.
batch-commit = false
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# Set keep alive option for tcp connection.
tcp-keep-alive = true
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31 changes: 28 additions & 3 deletions session/session_test.go
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Expand Up @@ -1925,13 +1925,13 @@ func (s *testSessionSuite) TestStatementErrorInTransaction(c *C) {
tk.MustQuery("select * from test where a = 1 and b = 11").Check(testkit.Rows())
}

func (s *testSessionSuite) TestStatementCountLimit(c *C) {
func (s *testSessionSuite) TestStatementCountLimitAndBatchCommit(c *C) {
tk := testkit.NewTestKitWithInit(c, s.store)
tk.MustExec("create table stmt_count_limit (id int)")
saved := config.GetGlobalConfig().Performance.StmtCountLimit
savedLimit := config.GetGlobalConfig().Performance.StmtCountLimit
config.GetGlobalConfig().Performance.StmtCountLimit = 3
defer func() {
config.GetGlobalConfig().Performance.StmtCountLimit = saved
config.GetGlobalConfig().Performance.StmtCountLimit = savedLimit
}()
tk.MustExec("begin")
tk.MustExec("insert into stmt_count_limit values (1)")
Expand All @@ -1946,6 +1946,31 @@ func (s *testSessionSuite) TestStatementCountLimit(c *C) {
tk.MustExec("insert into stmt_count_limit values (3)")
_, err = tk.Exec("insert into stmt_count_limit values (4)")
c.Assert(err, NotNil)

savedBatchFlag := config.GetGlobalConfig().Performance.BatchCommit
config.GetGlobalConfig().Performance.BatchCommit = true
defer func() {
config.GetGlobalConfig().Performance.BatchCommit = savedBatchFlag
}()
tk1 := testkit.NewTestKitWithInit(c, s.store)
tk.MustExec("SET SESSION autocommit = 1")
tk.MustExec("begin")
tk.MustExec("insert into stmt_count_limit values (5)")
tk1.MustQuery("select * from stmt_count_limit").Check(testkit.Rows())
tk.MustExec("insert into stmt_count_limit values (6)")
tk1.MustQuery("select * from stmt_count_limit").Check(testkit.Rows())
tk.MustExec("insert into stmt_count_limit values (7)")
tk1.MustQuery("select * from stmt_count_limit").Check(testkit.Rows("5", "6", "7"))
tk.MustExec("insert into stmt_count_limit values (8)")
tk1.MustQuery("select * from stmt_count_limit").Check(testkit.Rows("5", "6", "7"))
tk.MustExec("insert into stmt_count_limit values (9)")
tk1.MustQuery("select * from stmt_count_limit").Check(testkit.Rows("5", "6", "7"))
tk.MustExec("insert into stmt_count_limit values (10)")
tk1.MustQuery("select * from stmt_count_limit").Check(testkit.Rows("5", "6", "7"))
tk.MustExec("commit")
tk1.MustQuery("select * from stmt_count_limit").Check(testkit.Rows("5", "6", "7", "8", "9", "10"))
tk.MustExec("insert into stmt_count_limit values (11)")
tk1.MustQuery("select * from stmt_count_limit").Check(testkit.Rows("5", "6", "7", "8", "9", "10", "11"))
}

func (s *testSessionSuite) TestCastTimeToDate(c *C) {
Expand Down
19 changes: 14 additions & 5 deletions session/tidb.go
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Expand Up @@ -171,11 +171,20 @@ func runStmt(ctx context.Context, sctx sessionctx.Context, s sqlexec.Statement)
// If the user insert, insert, insert ... but never commit, TiDB would OOM.
// So we limit the statement count in a transaction here.
history := GetHistory(sctx)
if history.Count() > int(config.GetGlobalConfig().Performance.StmtCountLimit) {
err1 := se.RollbackTxn(ctx)
terror.Log(errors.Trace(err1))
return rs, errors.Errorf("statement count %d exceeds the transaction limitation, autocommit = %t",
history.Count(), sctx.GetSessionVars().IsAutocommit())
perfConfig := config.GetGlobalConfig().Performance
if history.Count() > int(perfConfig.StmtCountLimit) {
if !perfConfig.BatchCommit {
err1 := se.RollbackTxn(ctx)
terror.Log(errors.Trace(err1))
return rs, errors.Errorf("statement count %d exceeds the transaction limitation, autocommit = %t",
history.Count(), sctx.GetSessionVars().IsAutocommit())
}
err = se.NewTxn()
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// The transaction does not committed yet, we need to keep it in transaction.
// The last history could not be "commit" statement.
// It means it is impossible to start a new transaction at the end of the transaction (the "commit" statement).
// Because after the server executed "commit" statement, the session is out of the transaction.
se.sessionVars.SetStatusFlag(mysql.ServerStatusInTrans, true)
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What will happen if the last statement is a rollback, will there be a corner case that this line put the session into a new transaction while it should be rollbacked ?

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rollback is the same as commit.

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I will update the comment and add a rollback test case.

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s1:
set @@autocommit = 0;
insert into t value (1);
rollback;

s2:
insert into t values (1);
insert into t values (2);

s1:
select  * from t;    // what it see ?

@jackysp

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@jackysp jackysp Nov 16, 2018 •
edited
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So the statement count limit is 1 for this case?

}
}
return rs, errors.Trace(err)
Expand Down