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session: move more session vars to stmt context for retrying #8034

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merged 20 commits into from
Dec 10, 2018
Merged

session: move more session vars to stmt context for retrying #8034

merged 20 commits into from
Dec 10, 2018

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jackysp
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@jackysp jackysp commented Oct 24, 2018 •
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What problem does this PR solve?

Some session variables should be in statement context e.g. prev-affected rows and last insert id. If not the behavior will be incorrect when retrying.

What is changed and how it works?

Move the session variables to statement context.

Check List

Tests

  • Unit test

Code changes

  • Has exported function/method change

Related changes

  • Need to cherry-pick to the release branch

PTAL @tiancaiamao @disksing

This change is Reviewable

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jackysp commented Oct 24, 2018 

create table t (i int key);
insert into t values (1);
begin;
insert into t values (10);
update t set i = i + row_count();
-- before the following commit, run `update t set i = i - 1;` in another session.
commit;

we got

mysql> select * from t;
+----+
| i  |
+----+
| -1 |
|  9 |
+----+
2 rows in set (0.00 sec)

I think it should be

mysql> select * from t;
+----+
| i  |
+----+
| 1  |
| 11 |
+----+
2 rows in set (0.00 sec)

@tiancaiamao tiancaiamao added the require-LGT3 Indicates that the PR requires three LGTM. label Oct 24, 2018
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jackysp commented Oct 24, 2018

/run-all-tests

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jackysp commented Oct 25, 2018

PTAL @disksing @tiancaiamao

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Sorry I'm not really familiar with session.go. Maybe @coocood can help you.

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jackysp commented Oct 29, 2018

PTAL @zimulala

@jackysp jackysp added the priority/release-blocker This issue blocks a release. Please solve it ASAP. label Nov 5, 2018
lysu
lysu reviewed Nov 7, 2018
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session/session.go Outdated
@@ -111,10 +110,9 @@ type StmtHistory struct {
// Add appends a stmt to history list.
func (h *StmtHistory) Add(stmtID uint32, st sqlexec.Statement, stmtCtx *stmtctx.StatementContext, params ...interface{}) {
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stmtCtx *stmtctx.StatementContext can be remove too

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lysu commented Nov 7, 2018 •
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@jackysp PTAL this issue #2759, it seems has some reason previous keep stmtContext in history and only reset three fields? 🤣

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jackysp commented Nov 7, 2018

PTAL @coocood if you are free.

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jackysp commented Nov 8, 2018

/run-all-tests

crazycs520
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sessionctx/stmtctx/stmtctx.go Outdated
// PrevAffectedRows is the affected-rows value(DDL is 0, DML is the number of affected rows).
PrevAffectedRows int64
// params for prepared statements
PreparedParams []interface{}
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why change []types.Datum to []interface{} ?

executor/executor.go Outdated
@@ -1175,6 +1175,7 @@ func ResetContextOfStmt(ctx sessionctx.Context, s ast.StmtNode) (err error) {
sc.MemTracker = memory.NewTracker(s.Text(), vars.MemQuotaQuery)
sc.NowTs = time.Time{}
sc.SysTs = time.Time{}
sc.PreparedParams = []interface{}{}
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Maybe put PreparedParams in SessionVars can avoid re-allocating memory before every execution.

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Why not set it to nil

@jackysp jackysp changed the title session: reset context of statement when retrying session: move more session vars to stmt context for retrying Nov 16, 2018
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jackysp commented Nov 16, 2018

/run-all-tests

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jackysp commented Nov 28, 2018

PTAL @zimulala , @lysu

@jackysp jackysp mentioned this pull request Nov 29, 2018
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jackysp commented Nov 29, 2018

PTAL @tiancaiamao

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LGTM

@tiancaiamao tiancaiamao added the status/LGT2 Indicates that a PR has LGTM 2. label Nov 29, 2018
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jackysp commented Nov 30, 2018

PTAL @lysu @zimulala

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jackysp commented Dec 3, 2018

PTAL @lysu @zimulala

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jackysp commented Dec 4, 2018

PTAL @lysu @zimulala

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jackysp commented Dec 5, 2018

PTAL @lysu @zimulala

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jackysp commented Dec 7, 2018

PTAL @lysu @zimulala

lysu
lysu approved these changes Dec 10, 2018
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Reviewed 12 of 12 files at r1.
Reviewable status: :shipit: complete! all files reviewed, all discussions resolved

lysu
lysu suggested changes Dec 10, 2018
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miss approve by reviewable

lysu
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LGTM

@lysu lysu added status/LGT3 The PR has already had 3 LGTM. require-LGT3 Indicates that the PR requires three LGTM. and removed require-LGT3 Indicates that the PR requires three LGTM. status/LGT2 Indicates that a PR has LGTM 2. labels Dec 10, 2018
@jackysp jackysp merged commit ce622ec into pingcap:master Dec 10, 2018
jackysp added a commit to jackysp/tidb that referenced this pull request Dec 10, 2018
@jackysp
session: move more session vars to stmt context for retrying (pingcap…
863a35e 
…#8034)
@jackysp jackysp mentioned this pull request Dec 10, 2018
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jackysp added a commit that referenced this pull request Dec 12, 2018
@jackysp
session: move more session vars to stmt context for retrying (#8034) (#…
9ab1a50 
…8638)
iamzhoug37 pushed a commit to iamzhoug37/tidb that referenced this pull request Dec 13, 2018
@jackysp @iamzhoug37
session: move more session vars to stmt context for retrying (pingcap…
1b3c617 
…#8034)
@jackysp jackysp deleted the reset_ctx branch April 4, 2019 05:11
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@lysu lysu lysu approved these changes

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@jackysp @disksing @lysu @crazycs520 @tiancaiamao @zimulala