3329
MySQLERRORNotableQuery / DataMEDIUM confidence
Too many rows returned by FIND_IN_SET or similar function
Production Risk
Medium — query fails; no data is modified.
How to reproduce
trigger — this will error
trigger — this will error
SELECT FIND_IN_SET(id, (SELECT GROUP_CONCAT(id) FROM huge_table)) FROM t;
expected output
ERROR 3329 (HY000): Too many rows returned.
Fix
Use an indexed JOIN
Use an indexed JOIN
SELECT t.id FROM t JOIN huge_table h ON h.id = t.id;
Why this works
A JOIN with an index avoids materialising all IDs into a string.
What not to do
✕
Sources
Official documentation ↗
MySQL 8.0 — 3329 ER_TOO_MANY_FIND_ROWS
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