json_extract get wrong decimal when insert into table

[wjhuang2016]

Description

Bug Report

Please answer these questions before submitting your issue. Thanks!

1. What did you do?
   If possible, provide a recipe for reproducing the error.

create table ta(id decimal(60,2));
insert into ta values (JSON_EXTRACT('{"c": "1234567890123456789012345678901234567890123456789012345"}', '$.c'));
select * from ta;

2. What did you expect to see?

mysql> select * from ta;
+------------------------------------------------------------+
| id                                                         |
+------------------------------------------------------------+
| 1234567890123456789012345678901234567890123456789012345.00 |
+------------------------------------------------------------+
1 row in set (0.00 sec)

3. What did you see instead?

mysql> select * from ta;
+------------------------------------------------------------+
| id                                                         |
+------------------------------------------------------------+
| 1234567890123456800000000000000000000000000000000000000.00 |
+------------------------------------------------------------+
1 row in set (0.00 sec)

4. What version of TiDB are you using (tidb-server -V or run select tidb_version(); on TiDB)?

mysql> select tidb_version();
+-------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------+
| tidb_version()                                                                                                                                                                                                                                                                                                                |
+-------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------+
| Release Version: v4.0.0-alpha-177-gf9d85418e
Git Commit Hash: f9d85418ed13f54c02acfa0e97af32fb64f008e1
Git Branch: master
UTC Build Time: 2019-09-12 11:15:49
GoVersion: go version go1.12.4 linux/amd64
Race Enabled: false
TiKV Min Version: v3.0.0-60965b006877ca7234adaced7890d7b029ed1306
Check Table Before Drop: false |
+-------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------+
1 row in set (0.00 sec)

SIG slack channel

#sig-exec

Score

300

Mentor

• @lzmhhh123

[Deardrops]

In TiDB:

mysql> select JSON_EXTRACT('{"c": "1234567890123456789012345678901234567890123456789012345"}', '$.c');
+-----------------------------------------------------------------------------------------+
| JSON_EXTRACT('{"c": "1234567890123456789012345678901234567890123456789012345"}', '$.c') |
+-----------------------------------------------------------------------------------------+
| "1234567890123456789012345678901234567890123456789012345"                               |
+-----------------------------------------------------------------------------------------+
1 row in set (0.01 sec)

mysql> select CAST(JSON_EXTRACT('{"c": "1234567890123456789012345678901234567890123456789012345"}', '$.c') as decimal(60,2));
+----------------------------------------------------------------------------------------------------------------+
| CAST(JSON_EXTRACT('{"c": "1234567890123456789012345678901234567890123456789012345"}', '$.c') as decimal(60,2)) |
+----------------------------------------------------------------------------------------------------------------+
|                                                     1234567890123456789012345678901234567890123456789012345.00 |
+----------------------------------------------------------------------------------------------------------------+
1 row in set (0.00 sec)

and

mysql> create table ta(id decimal(60,2));
Query OK, 0 rows affected (0.01 sec)

mysql> insert into ta values (1234567890123456789012345678901234567890123456789012345.00);
Query OK, 1 row affected (0.01 sec)

mysql> select * from ta;
+------------------------------------------------------------+
| id                                                         |
+------------------------------------------------------------+
| 1234567890123456789012345678901234567890123456789012345.00 |
+------------------------------------------------------------+
1 row in set (0.00 sec)

[ghost]

Confirming this issue still exists in master:

drop table if exists ta;
create table ta(id decimal(60,2));
insert into ta values (JSON_EXTRACT('{"c": "1234567890123456789012345678901234567890123456789012345"}', '$.c'));
select * from ta;

..

mysql> select * from ta;
+------------------------------------------------------------+
| id                                                         |
+------------------------------------------------------------+
| 1234567890123456800000000000000000000000000000000000000.00 |
+------------------------------------------------------------+
1 row in set (0.00 sec)

mysql> select tidb_version()\G
*************************** 1. row ***************************
tidb_version(): Release Version: v4.0.0-beta.2-782-gb72e47e6d
Edition: Community
Git Commit Hash: b72e47e6db8863c08e47714391cf937b0f1c3269
Git Branch: master
UTC Build Time: 2020-07-15 01:26:06
GoVersion: go1.13
Race Enabled: false
TiKV Min Version: v3.0.0-60965b006877ca7234adaced7890d7b029ed1306
Check Table Before Drop: false
1 row in set (0.00 sec)

[ichn-hu]

/unlabel challenge-program

[ti-challenge-bot]

The issue has been removed from the challenge program.

[ti-srebot]

Please edit this comment or add a new comment to complete the following information

Not a bug

1. Remove the 'type/bug' label
2. Add notes to indicate why it is not a bug

Duplicate bug

1. Add the 'type/duplicate' label
2. Add the link to the original bug

Bug

Note: Make Sure that 'component', and 'severity' labels are added
Example for how to fill out the template: #20100

1. Root Cause Analysis (RCA) (optional)

2. Symptom (optional)

3. All Trigger Conditions (optional)

4. Workaround (optional)

5. Affected versions

6. Fixed versions