| Bug #121358 | Prepared statement does not reflect updated group_concat_max_len during execution | ||
|---|---|---|---|
| Submitted: | 23 Sep 7:46 | Modified: | 23 Sep 10:29 |
| Reporter: | Xiaoyuan Xie | Email Updates: | |
| Status: | Verified | Impact on me: | |
| Category: | MySQL Server: Optimizer | Severity: | S2 (Serious) |
| Version: | 9.7.2 | OS: | Ubuntu |
| Assigned to: | CPU Architecture: | Any | |
[23 Sep 10:29]
Chaithra Marsur Gopala Reddy
Hi Xiaoyuan Xie, Thank you for the test case. Verified as described. Increasing the group_concat_max_len seems to trigger re-preparation but not decreasing it. So marking this as a bug because of the inconsistency.
Description: A prepared statement containing GROUP_CONCAT() does not reflect a subsequent change to the session variable group_concat_max_len. In the following test case, the statement is prepared first, and group_concat_max_len is then set to 4. When the prepared statement is executed, GROUP_CONCAT() returns the complete 5-character string instead of truncating the result to the configured maximum length of 4. How to repeat: PREPARE s FROM 'SELECT GROUP_CONCAT(''12345'')'; SET SESSION group_concat_max_len = 4; EXECUTE s; Actual Result: 12345 Expected Result: 1234