types: Regard TypeNewDecimal as not a hasVariantFieldLength type. (#21849)

[ti-srebot]

cherry-pick #21849 to release-4.0

---

What problem does this PR solve?

Issue Number: close #21804

Problem Summary:

Tiflash will check whether Decimal's flen is between 1 and 65. But TiDB enable will push down a Decimal constant with flen -1 from the environment parameter.

What is changed and how it works?

What's Changed:

When creating a decimal variable from Parameter, don't set it's flen to -1.

Other types in hasVariantFieldLength don't have this problem.

Related changes

• Need to cherry-pick to the release 4.0

Check List

Tests

• Unit test
  (will be added to tiflash repo)
• Integration test
• Manual test (add detailed scripts or steps below)

create table t (c_decimal decimal);
alter table t set tiflash replica 1; -- wait ready.
insert into t values (9), (10);
prepare s1 from 'select * from t where ? <= c_decimal';
set @v1 = 9.330;
execute s1 using @v1;
+-----------+
| c_decimal |
+-----------+
|        10 |
+-----------+

test for issue/8644

mysql> create table t(d decimal(3,2));
mysql> alter table t set tiflash replica 1; --wait ready

mysql> insert into t values (1.11), (2.222);
Query OK, 2 rows affected, 1 warning (0.03 sec) -- the warning is: Truncated incorrect DECIMAL value: '2.222'
mysql> insert into t values (33.3);
ERROR 1264 (22003): Out of range value for column 'd' at row 1

mysql> insert into t values ('1.11'), ('2.222');
Query OK, 2 rows affected, 1 warning (0.01 sec)
mysql> insert into t values ('33.3');
ERROR 1264 (22003): Out of range value for column 'd' at row 1

mysql> prepare s1 from 'insert t (d) values (?), (?)';
mysql> prepare s2 from 'insert t (d) values (?)';

mysql> set @a='1.11', @b='2.222', @c='33.3';
mysql> execute s1 using @a, @b;
Query OK, 2 rows affected, 1 warning (0.01 sec)
mysql> execute s2 using @c;
ERROR 1264 (22003): Out of range value for column 'd' at row 1

mysql> set @a=1.11, @b=2.222, @c=33.3;
mysql> execute s1 using @a, @b;
Query OK, 2 rows affected, 1 warning (0.02 sec)
mysql> execute s2 using @c;
ERROR 1264 (22003): Out of range value for column 'd' at row 1

Side effects

• N/A

Release note

• Fixed the issue that using prepare statement to cache execution plan caused tiflash to return Wrong precision.

[ti-srebot]

/run-all-tests

[ti-srebot]

@LittleFall you're already a collaborator in bot's repo.

[LittleFall]

/run-unit-test

[eurekaka]

LGTM

[ti-srebot]

@eurekaka, Thanks for your review. The bot only counts LGTMs from Reviewers and higher roles, but you're still welcome to leave your comments. See the corresponding SIG page for more information. Related SIG: execution(slack).

[lzmhhh123]

LGTM

[LittleFall]

/merge

[ti-srebot]

Sorry @LittleFall, this branch cannot be merged without an approval of release maintainers.

[eurekaka]

/merge

[ti-srebot]

Sorry @eurekaka, this branch's release version is in progress, please contact zhouqiang-cl,shuke987,jebter,you06 for more details.

[eurekaka]

/run-all-tests