I'm retrieving the data with MySQL function called "GROUP_CONCAT()".
But when I checked the result of "GROUP_CONCAT()" function related column, it was missing some data.
When I google the record missing issue with "GROUP_CONCAT()" function, in the official MySQL site they have mentioned as,
There is a global variable called group_concat_max_len and it will permit the maximum result length in bytes for the GROUP_CONCAT() function, the default value of it as 1024.
Therefore it seems I have to increase that value with following MySQL command,
SET GLOBAL group_concat_max_len = 1000000;
Therefore set this value permanently, I have to edit the MySQL server related configuration file (my.cnf or my.ini) and have to restart the server.
But unfortunately I haven't any permission to do so.
Therefore can you please help me to find out some alternative solution to fix this issue.
Thanks a lot.
Use SET SESSION instead:
SET SESSION group_concat_max_len = 1000000;
Unlike SET GLOBAL, SET SESSION does not require super privilege.
Reference
Related
I want to set the general_log and general_log_file variables using SQLAlchemy, is there a way to do this? I've been Googling around and can't find anything on the topic.
You can execute any raw SQL query which you need (of course you have to get appropriate rights in the session). To change a variable run something like this:
# change variable name and values to what you need
connection.execute("SET SESSION query_cache_type = OFF")
As mentioned previously, you could use the following code the set a variable using the raw Connection object.
connection.execute("SET SESSION query_cache_type = OFF")
If you have a Session object, you can retrieve the underlying Connection object using the Session.connection() function.
So your code could look as follows.
session.connection().execute("SET SESSION query_cache_type = OFF")
I ran the command as root:
set ##auto_increment_offset = 2;
But the effect cannot be seen from other connections. Why not? It is global.
From http://dev.mysql.com/doc/refman/5.1/en/replication-options-master.html:
"If the global value of either variable is set, its effects persist until the global value is changed or overridden by setting the session value, or until mysqld is restarted."
That doesn't seem to agree with what I am seeing.
Ultimately, I would like to know if there any way to permanently set the offset for all clients without restarting mysqld?
As per MySQL documentation you need to set values of auto_increment_offset for both GLOBAL and SESSION.
SET GLOBAL auto_increment_offset = 2;
SET SESSION auto_increment_offset = 2;
SHOW VARIABLES LIKE '%auto_increment_offset%';
If the global value of either variable is set, its effects persist until the global value is changed or overridden by setting the session value, or until mysqld is restarted. If the local value is set, the new value affects AUTO_INCREMENT columns for all tables into which new rows are inserted by the current user for the duration of the session, unless the values are changed during that session.
To set it globally you should add prefix 'GLOBAL' or '##global.'. For example -
SET ##GLOBAL.auto_increment_offset = 2;
The '##' is the same as 'SESSION' or '##session.', it sets session variable.
Using System Variables.
I am using a group_concat to concatenate a lot of rows into one.
I set group concat to 10000 using:
SET group_concat_max_len = 10000;
But even then, my output cells remain incomplete and end with ...
I tried setting group_concat_max_len = 20000 and even that didn't help.
I also tried setting group_concat_max_len to 99999999. It still doesn't complete my output text. And I checked one of the group concat stops at Length = 230 characters and then gives ...
Is there any other way?
Check out this link: https://dev.mysql.com/doc/refman/5.6/en/server-system-variables.html#sysvar_group_concat_max_len
All the MySQL configuration variables are documented on that page, with details like minimum, maximum, default value, whether you can set them globally or per-session, whether you can change them on a running instance or does it require a restart, and other description of usage.
The maximum value for group_concat_max_len is 18446744073709551615.
The group-concat string does not end with "..." If you try to group too much text, it just gets truncated. So I wonder if the problem is not with MySQL's settings, but with the display of your cells.
For 32bit systems, the maximum value is 4294967295
For 64 bit systems, the maximum value is 18446744073709551615.
You can set the variable for your current session using
SET SESSION group_concat_max_len=4294967295;
To set the variable forever use
SET GLOBAL group_concat_max_len=4294967295;
(see http://dev.mysql.com/doc/refman/5.7/en/server-system-variables.html#sysvar_group_concat_max_len)
Following this post: POST ABOUT CONCAT
My problem is that i have many rows CONCAT into one row. For example if i have 10 rows with string around 50 chars, my query will show me only 6-7 of that rows or something like that.
I searech in stack and google and i found that i can change CONCAT max length by command: SET group_concat_max_len := ##max_allowed_packet. What i am doing wrong?
EDIT:
When i SHOW VARIABLES LIKE 'group_concat_max_len' it's shows me 1024.
Mysql version 5.0.96-log. Tables type: MyISAM. Looks like it dont have any limits, i try to select simple varchar with 2000 chars, and it looks fine.
I have 3 tables: 1st - Item with ItemID, 2nd - Descriptionpack with ItemID and DescriptionID, 3rd Description with DescriptionID.
Select
DISTINCT Item.ItemID as item
,GROUP_CONCAT(Description.DescriptionID) AS description
From Item
LEFT OUTER JOIN descriptionpack
on Item.ItemID=descriptionpack.ItemID
LEFT OUTER JOIN description
on descriptionpack.descriptionID=description.descriptionID
GROUP BY item
EDIT2: I think i found the problem, i said my problem to my provider and they answer me this:
I reviewed your question with our hosting team. You wouldn't be able
to change the global settings for that and other variables. However,
you should be able to set that variable on a per session basis by
setting it first, before other queries. Hope that helps.
So now the problem is, how to do that.
Presumably you're using GROUP_CONCAT(), not simple CONCAT().
The default value of the group_concat_max_len is 1024, which is a pretty small limit if you're building up big long concatenations.
To change it, use this command. I've set the length in this example to 100,000. You could set it to anything you need.
SET SESSION group_concat_max_len = 100000;
The usual value for max_allowed_packet is one megabyte, which is likely more than you need.
group_concat_max_len itself has an effectively unlimited size. It's limited only by the unsigned word length of the platform: 2^32-1 on a 32-bit platform and 2^64-1 on a 64-bit platform.
If that still isn't enough for your application, it's time to take #eggyal's suggestion and rethink your approach.
You need change group_concat_max_len default value in the bellow config file
**my.cnf file(Linux) and my.ini file(windows)**
[mysqld]//Add this line group_concat_max_len=15000 under mysqld section
group_concat_max_len=15000
Note: After change is done You need to restart your MySQL server.
my.cnf file path in linux :
1. /etc/my.cnf
2./etc/mysql/my.cnf
3.$MYSQL_HOME/my.cnf
4.[datadir]/my.cnf
5.~/.my.cnf
I ran the command as root:
set ##auto_increment_offset = 2;
But the effect cannot be seen from other connections. Why not? It is global.
From http://dev.mysql.com/doc/refman/5.1/en/replication-options-master.html:
"If the global value of either variable is set, its effects persist until the global value is changed or overridden by setting the session value, or until mysqld is restarted."
That doesn't seem to agree with what I am seeing.
Ultimately, I would like to know if there any way to permanently set the offset for all clients without restarting mysqld?
As per MySQL documentation you need to set values of auto_increment_offset for both GLOBAL and SESSION.
SET GLOBAL auto_increment_offset = 2;
SET SESSION auto_increment_offset = 2;
SHOW VARIABLES LIKE '%auto_increment_offset%';
If the global value of either variable is set, its effects persist until the global value is changed or overridden by setting the session value, or until mysqld is restarted. If the local value is set, the new value affects AUTO_INCREMENT columns for all tables into which new rows are inserted by the current user for the duration of the session, unless the values are changed during that session.
To set it globally you should add prefix 'GLOBAL' or '##global.'. For example -
SET ##GLOBAL.auto_increment_offset = 2;
The '##' is the same as 'SESSION' or '##session.', it sets session variable.
Using System Variables.