COLUMN_CHECK() does not always detect data truncation

select @@max_allowed_packet;

# 1073741824

select column_check(column_create('a', 1, 'b', repeat('1234567890', 6554)));

# 1

set @txt = (select repeat('1234567890', 6554));

select column_check(column_create('a', 1, 'txt', @txt));

# 1

select column_check(column_create('a', 1, 'css', @txt));

# 1

create database if not exists dyncol_test;

use dyncol_test;

drop table if exists t;

create table t (a int, b varchar(255), dcols blob);

insert into t (a, b, dcols) values (1, 'two', column_create('txt', @txt));

select column_check(dcols),

    substring(column_get(dcols, 'txt' as char), 1, 40),

    substring(column_json(dcols), 1, 40) from t;

# 1   1234567890123456789012345678901234567890    {"txt":"12345678901234567890123456789012

delete from t;

insert into t (a, b, dcols) values (1, 'two', column_create('one', 1, 'txt', @txt));

select column_check(dcols),

    substring(column_get(dcols, 'txt' as char), 1, 40),

    substring(column_json(dcols), 1, 40) from t;

# 1   1234567890123456789012345678901234567890    {"one":1,"txt":"123456789012345678901234

delete from t;

insert into t (a, b, dcols) values (1, 'two', column_create('css', @txt));

select column_check(dcols),

    substring(column_get(dcols, 'css' as char), 1, 40),

    substring(column_json(dcols), 1, 40) from t;

# 1   1234567890123456789012345678901234567890    {"css":"12345678901234567890123456789012

delete from t;

insert into t (a, b, dcols) values (1, 'two', column_create('one', 1, 'css', @txt));

select column_check(dcols),

    substring(column_get(dcols, 'css' as char), 1, 40),

    substring(column_json(dcols), 1, 40) from t;

# ERROR 1919 (HY000) at line 31: Encountered illegal format of dynamic column string

# Looks like the conditions for the error are:

# 1. dynamic column blob size greater than 64kB

# 2. dynamic column blob is saved to a table

# 3. dynamic column blob contains more than one dynamic columns

# 4. the dynamic column with the long value is named 'css' and not 'txt' !!!