Mysql 8.0.22 month() function and group by - mysql

Question

I can't seem to figure out an underlying datatype issue (at least I think it is a datatype issue). Obviously writing here as I can't seem to put my finger on what is going wrong
Some background:
We have been trying to upgrade from mysql 5.7 to mysql 8.0.22 and I am tasked in checking database issues regarding inconsistencies. We fixed a timestamp datatype issue earlier in making sure both the times were in the same timezones and that seems to be in check. However, on mysql 8.0.22 I am facing a weird issue when grouping on this timestamp. Here is a small sample of the output that is eluding me:
The query essentially goes like
select year(date)
, month(date)
, *aggregation(a)*
, *aggregation(b)*
etc.
from blabla
join blabla
group by 1,2
It is just not making the month unique. I have a work around by using dateformat function however, I am just curious what might be causing this issue. This same query is working fine on my 5.7 db. I have checked that both databases are exact replicas in multiple ways. Any insight would be greatly appreciated.
Thank you!
edit As people wanted exact context as to what is going on. Here is a simplified query from the same table that shows the problem at hand.
edit no 2 I am adding the information schema and 10 rows for visibility of what the data looks like.
sample data:
schema:
Let me know if there is anything else you need to help me solve this. Apologies for the incomplete information. This part of database management/engineering or technical know how eludes me.
show create table results :
CREATE TABLE `order_status_history` (
`id` int NOT NULL AUTO_INCREMENT,
`order_id` int NOT NULL,
`admin_user_id` int NOT NULL,
`admin_user_name` varchar(255) NOT NULL,
`order_status` varchar(255) NOT NULL,
`date_update` timestamp NOT NULL DEFAULT CURRENT_TIMESTAMP,
`o_type` enum('R','C','D') DEFAULT NULL,
PRIMARY KEY (`id`),
KEY `indx_order_id` (`order_id`),
KEY `indx_order_status` (`order_status`),
KEY `indx_o_type` (`o_type`)
) ENGINE=InnoDB AUTO_INCREMENT=2375978 DEFAULT CHARSET=latin1

Answer 1

According to the MySQL 8.0 docs, the GETMONTH() function works with a date, not a timestamp. So you would need to do something like GETMONTH(FROM_UNIXTIME(date_update)) for your query to return expected results. What's interesting is that you said this was working in MySQL 5.7, but the docs for that function are identical to that found for 8.0. The one difference that your two installations might have is with the lc_time_names system variable, but this is just speculation.
A similar question was asked on this site about eight years ago, and the accepted answer is the same as I outlined above. 🤔