EC
3226
MySQLERRORNotablePartitioningHIGH confidence

HASH partition reorganization must use the same number of partitions

Production Risk

Low — DDL error.

Why it happens
  1. 1Attempting to reorganize HASH or KEY partitions by changing the number of partitions without using COALESCE or ADD PARTITION.
How to reproduce
trigger — this will error
trigger — this will error
ALTER TABLE t1 REORGANIZE PARTITION INTO (PARTITION p0, PARTITION p1, PARTITION p2);

expected output

ERROR 3226 (HY000): REORGANIZE PARTITION for HASH/KEY must use same number of partitions.

Fix 1

Use COALESCE PARTITION to reduce

Use COALESCE PARTITION to reduce
ALTER TABLE t1 COALESCE PARTITION 2;

Why this works

COALESCE PARTITION is the correct method to reduce HASH partition count.

Fix 2

Use ADD PARTITION to increase

Use ADD PARTITION to increase
ALTER TABLE t1 ADD PARTITION PARTITIONS 2;

Why this works

ADD PARTITION is the correct method to add HASH partitions.

What not to do

✕

Sources
Official documentation ↗

MySQL 8.0 — 3226 ER_REORG_HASH_ONLY_ON_SAME_NO2

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