EC
1491
MySQLERRORNotablePartitioningHIGH confidence

Wrong number of subpartitions defined

Production Risk

Low — DDL error; the table will not be created.

What this means

ER_PARTITION_WRONG_NO_SUBPART_ERROR (1491, SQLSTATE HY000) is raised when the number of subpartition definitions does not match the SUBPARTITIONS N count.

Why it happens
  1. 1SUBPARTITIONS N specified but a different number of subpartition definitions provided
  2. 2Explicit subpartition count inconsistent with the definitions
How to reproduce
trigger — this will error
trigger — this will error
CREATE TABLE t (id INT, created DATE)
PARTITION BY RANGE(YEAR(created))
SUBPARTITION BY HASH(id) SUBPARTITIONS 3 (
  PARTITION p0 VALUES LESS THAN (2020) (
    SUBPARTITION sp0,
    SUBPARTITION sp1  -- Only 2, but SUBPARTITIONS 3 was declared
  )
);

expected output

ERROR 1491 (HY000): Wrong number of subpartitions defined, mismatch with previous setting

Fix

Match subpartition definitions to SUBPARTITIONS N

Match subpartition definitions to SUBPARTITIONS N
CREATE TABLE t (id INT, created DATE)
PARTITION BY RANGE(YEAR(created))
SUBPARTITION BY HASH(id) SUBPARTITIONS 2 (
  PARTITION p0 VALUES LESS THAN (2020) (
    SUBPARTITION sp0,
    SUBPARTITION sp1
  )
);

Why this works

The SUBPARTITIONS N count and the number of explicitly named subpartitions must match.

Sources
Official documentation ↗

MySQL 8.0 — 1491 ER_PARTITION_WRONG_NO_SUBPART_ERROR

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