MySQL Bugs: #96363: Incorrect "Too many columns" for mysql create table with comments

Bug #96363	Incorrect "Too many columns" for mysql create table with comments
Submitted:	29 Jul 2019 11:00	Modified:	29 Jul 2019 11:37
Reporter:	dennis gao	Email Updates:
Status:	Verified	Impact on me:	None
Category:	MySQL Server: DDL	Severity:	S3 (Non-critical)
Version:	5.7.23, 5.7.27	OS:	CentOS (7.3)
Assigned to:		CPU Architecture:	Any

Description:
For a table with large number of columns and each column with long comment string, mysql may fail to create table due to "Too many columns".
But if we delete all comments, the table can be created normally.

How to repeat:
Use sql1.txt to create table will fail due to "ERROR 1117 (HY000): Too many columns":
But use sql2.txt  can be executed normally:

Suggested fix:
The innodb column num limit is 1017, it should not be affected by the column comment.

the create table sql will fail

Attachment: sql1.txt (text/plain), 108.33 KiB.

the create table sql will success

Attachment: sql2.txt (text/plain), 31.80 KiB.

Hello Dennis Gao,

Thank you for the report and test case.
Observed that 5.7.27 is affected.

Thanks,
Umesh

- 5.7.27

bin/mysql -uroot -S /tmp/mysql_ushastry.sock test < ../mysql-8.0.17/1.sql
ERROR 1117 (HY000) at line 1: Too many columns

- 8.0.17 - looks like this issue is no longer seen

bin/mysql -uroot -S /tmp/mysql_ushastry.sock test < ./1.sql
bin/mysql -uroot -S /tmp/mysql_ushastry.sock test -e 'show create table test.test_db\G'
.
| test_db | CREATE TABLE `test_db` (
  `ID` char(38) NOT NULL COMMENT '电电电电电电',
  `COL_1` decimal(21,6) DEFAULT NULL COMMENT '（电电电电）电电电电电电电电电电电电电电电-1第1行第3列单元格值',
  `COL_2` decimal(21,6) DEFAULT NULL COMMENT '（电电电电）电电电电电电电电电电电电电电电-1第2行第3列单元格值',
.
  `COL_772` decimal(21,6) DEFAULT NULL COMMENT '（电电电电）电电电电电电电电电电电电电电电-1第60行第7列单元格值',
  `COL_773` decimal(21,6) DEFAULT NULL COMMENT '（电电电电）电电电电电电电电电电电电电电电-1第61行第7列单元格值',
  PRIMARY KEY (`ID`)
) ENGINE=InnoDB DEFAULT CHARSET=utf8mb4 COLLATE=utf8mb4_0900_ai_ci |