How to Increase MySQL GROUP_CONCAT() Maximum Length When Parameter Modification is Restricted?

Increasing MySQL GROUP_CONCAT() Maximum Length

MySQL's GROUP_CONCAT() function enables users to concatenate values from multiple rows into a single string. However, this function faces a default maximum length limitation of 1024 characters.

Overcoming the Limitation

While increasing the group_concat_max_len parameter is a standard method to extend the maximum length, it may not be feasible in certain hosting environments where parameter modifications are restricted.

Alternative Solution

To bypass the parameter restriction, utilize the session-specific SET SESSION command. By setting the group_concat_max_len before executing the GROUP_CONCAT() query, you can temporarily increase the maximum length.

Usage

The session-specific SET SESSION command follows this syntax:

SET SESSION group_concat_max_len = {new_limit};

For example:

SET SESSION group_concat_max_len = 1000000;

Once the session-scoped setting is applied, execute the GROUP_CONCAT() query as usual:

select group_concat(column) from table group by column;

Note:

The SET SESSION command affects only the current session. When creating a new connection or session, the session-specific settings are reset, requiring you to reapply the group_concat_max_len setting.

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