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parser: add nowait keyword, add for update no wait grammar, and related error… #582

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merged 4 commits into from
Oct 18, 2019
Merged

parser: add nowait keyword, add for update no wait grammar, and related error… #582

merged 4 commits into from
Oct 18, 2019

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cfzjywxk
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… code/msg

What problem does this PR solve?

support select for update nowait

# Session 1:

mysql> CREATE TABLE t (i INT, PRIMARY KEY (i)) ENGINE = InnoDB;

mysql> INSERT INTO t (i) VALUES(1),(2),(3);

mysql> START TRANSACTION;

mysql> SELECT * FROM t WHERE i = 2 FOR UPDATE;
+---+
| i |
+---+
| 2 |
+---+

# Session 2:

mysql> START TRANSACTION;

mysql> SELECT * FROM t WHERE i = 2 FOR UPDATE NOWAIT;
ERROR 3572 (HY000): Statement aborted because lock(s) could not be acquired immediately and NOW

What is changed and how it works?

Check List

Tests

  • Unit test

Code changes

  • Has exported variable/fields change

Side effects

Related changes

  • Need to update the documentation

@cfzjywxk cfzjywxk requested review from lysu, coocood, tiancaiamao, jackysp and a team October 17, 2019 02:35
@cfzjywxk cfzjywxk mentioned this pull request Oct 17, 2019
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codecov bot commented Oct 17, 2019 •
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Codecov Report

Merging #582 into master will increase coverage by <.01%.
The diff coverage is 75%.

Impacted file tree graph

@@            Coverage Diff             @@
##           master     #582      +/-   ##
==========================================
+ Coverage   71.82%   71.83%   +<.01%     
==========================================
  Files          32       32              
  Lines        7834     7836       +2     
==========================================
+ Hits         5627     5629       +2     
  Misses       1676     1676              
  Partials      531      531
Impacted Files Coverage Δ
parser.go 70.37% <ø> (ø) ⬆️
misc.go 96.49% <ø> (ø) ⬆️
ast/util.go 75% <0%> (ø) ⬆️
ast/dml.go 73.92% <100%> (+0.03%) ⬆️

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kennytm
kennytm reviewed Oct 17, 2019
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From the description in https://dev.mysql.com/doc/refman/8.0/en/select.html#idm140006656103232, it's more appropriate to make NOWAIT its own modifier rather than grouping FOR UPDATE NOWAIT as a whole thing.

    [FOR {UPDATE | SHARE} [OF tbl_name [, tbl_name] ...] [NOWAIT | SKIP LOCKED] 
      | LOCK IN SHARE MODE]]

@coocood
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coocood commented Oct 17, 2019

NOWAIT is an unreserved keyword, we need to add it to UnReservedKeyword: section in the parser.y.

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From the description in https://dev.mysql.com/doc/refman/8.0/en/select.html#idm140006656103232, it's more appropriate to make NOWAIT its own modifier rather than grouping FOR UPDATE NOWAIT as a whole thing.

    [FOR {UPDATE | SHARE} [OF tbl_name [, tbl_name] ...] [NOWAIT | SKIP LOCKED] 
      | LOCK IN SHARE MODE]]

we're currently groupint "FOR UPDATE" as a whole, and "SelectLockType" is defined as single int type, maybe we need to some refactorations on this for 8.0 compatibility ? There will be some other related work, do this refactoration in the future?
@coocood @kennytm

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coocood commented Oct 17, 2019

LGTM

@cfzjywxk cfzjywxk requested a review from kennytm October 18, 2019 04:43
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@jackysp @tiancaiamao PTAL

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kennytm commented Oct 18, 2019

we're currently groupint "FOR UPDATE" as a whole, and "SelectLockType" is defined as single int type, maybe we need to some refactorations on this for 8.0 compatibility ? There will be some other related work, do this refactoration in the future?

@cfzjywxk IMO it's better to turn SelectLockType into a struct now, or add a new member to SelectStmt indicating whether it is NOWAIT (and SKIP LOCKED in the future).

To support SelectLockForUpdateNoWait you'll need to modify TiDB once now, and later when you refactor for 8.0 compatibility you'll need to modify the code again. So I think it's better to choose a solution which we know is going to last.

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coocood commented Oct 18, 2019

@kennytm
We can modify the code again later when we need to.
It's not certain if we need to support those features.

jackysp
jackysp approved these changes Oct 18, 2019
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LGTM

@coocood coocood merged commit 7bd38fd into pingcap:master Oct 18, 2019
@cfzjywxk cfzjywxk deleted the nowait branch October 18, 2019 07:13
@cfzjywxk cfzjywxk mentioned this pull request Nov 6, 2019
Merged
tiancaiamao pushed a commit to tiancaiamao/parser that referenced this pull request Apr 27, 2021
@cfzjywxk @coocood
parser: add nowait keyword, add for update no wait grammar, and relat…
9c398ac 
…ed error… (pingcap#582)
lyonzhi pushed a commit to lyonzhi/parser that referenced this pull request Apr 25, 2024
@cfzjywxk @coocood
parser: add nowait keyword, add for update no wait grammar, and relat…
daa9991 
…ed error… (pingcap#582)
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@jackysp jackysp jackysp approved these changes

@lysu lysu Awaiting requested review from lysu

@coocood coocood Awaiting requested review from coocood

@tiancaiamao tiancaiamao Awaiting requested review from tiancaiamao

@kennytm kennytm Awaiting requested review from kennytm

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