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Description

This error occurs during an `ALTER TABLE` operation when the new partition definition specifies a different number of partitions than what is currently defined for the table. It indicates an attempt to change the total partition count without using the correct partitioning clauses, leading to an inconsistency in the table's schema update.

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Error Message

Wrong number of partitions defined, mismatch with previous setting

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Known Causes

3 known causes

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Direct Partition Count Change

Attempting to directly change the total number of partitions using `ALTER TABLE ... PARTITIONS n` when the table already has a different number of partitions defined.

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Incorrect ALTER TABLE Syntax

Using `ALTER TABLE` with a `PARTITIONS n` clause in a way that conflicts with the table's existing partition definition, instead of using `ADD`, `DROP`, or `REORGANIZE PARTITION`.

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Schema Drift or Script Mismatch

Executing a schema migration script where the `ALTER TABLE` statement's partition definition doesn't align with the current state of the table in the database.

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Solutions

3 solutions available

1. Recreate Table with Correct Partitioning medium

Drop the existing table and recreate it with the intended partition count.

1

Identify the current table structure and data. You'll need to know the column definitions and the partitioning scheme you intended.

SHOW CREATE TABLE your_table_name;

2

Backup the data from the problematic table. This is crucial to avoid data loss.

CREATE TABLE your_table_name_backup AS SELECT * FROM your_table_name;

3

Drop the existing table. Be absolutely sure you have a backup before proceeding.

DROP TABLE your_table_name;

4

Recreate the table with the correct number of partitions. Ensure the `PARTITIONS` clause matches your desired configuration.

CREATE TABLE your_table_name (
    id INT NOT NULL,
    data VARCHAR(255)
    -- other columns...
) ENGINE=InnoDB
PARTITION BY RANGE (id) (
    PARTITION p0 VALUES LESS THAN (10),
    PARTITION p1 VALUES LESS THAN (20),
    PARTITION p2 VALUES LESS THAN (30)
    -- ... add the correct number of partitions here
);

5

Restore the data from the backup into the newly created table.

INSERT INTO your_table_name SELECT * FROM your_table_name_backup;

6

Clean up the backup table.

DROP TABLE your_table_name_backup;

2. Alter Table to Add/Remove Partitions (for existing tables) medium

Modify the table's partitioning by adding or removing partitions sequentially.

1

Determine the current number of partitions and the desired number. You can find the current partition count by inspecting the `CREATE TABLE` statement or using `SHOW CREATE TABLE`.

SHOW CREATE TABLE your_table_name;

2

If you need to add partitions, use `ALTER TABLE ... ADD PARTITION`. Ensure the new partition definition is valid and aligns with your partitioning scheme (e.g., `VALUES LESS THAN` for RANGE partitioning).

ALTER TABLE your_table_name
ADD PARTITION (PARTITION p3 VALUES LESS THAN (40));

3

If you need to remove partitions, use `ALTER TABLE ... DROP PARTITION`. Be cautious, as data within the dropped partition will be lost unless handled carefully.

ALTER TABLE your_table_name
DROP PARTITION p3;

4

Repeat the `ADD PARTITION` or `DROP PARTITION` commands until the table has the correct number of partitions. This process can be time-consuming for tables with many partitions.

ALTER TABLE your_table_name
ADD PARTITION (PARTITION p4 VALUES LESS THAN (50));

3. Review and Correct Partitioning in Application Code or Migration Scripts easy

Identify and fix the source of the incorrect partition count definition in your application or deployment scripts.

1

Examine any SQL scripts or application code that defines or modifies the partitioning of `your_table_name`. Look for `CREATE TABLE` or `ALTER TABLE` statements.

search_pattern = 'PARTITION BY.*PARTITION p[0-9]+'

2

Locate the `PARTITIONS` clause within these statements and ensure the number of defined partitions accurately reflects your intended configuration.

CREATE TABLE your_table_name (
    -- ...
) PARTITION BY RANGE (id) (
    PARTITION p0 VALUES LESS THAN (10),
    PARTITION p1 VALUES LESS THAN (20)
    -- Ensure this list has the correct number of entries
);

3

Correct any discrepancies in the number of partitions defined in your scripts.

CREATE TABLE your_table_name (
    -- ...
) PARTITION BY RANGE (id) (
    PARTITION p0 VALUES LESS THAN (10),
    PARTITION p1 VALUES LESS THAN (20),
    PARTITION p2 VALUES LESS THAN (30) -- Corrected
);

4

Re-run the corrected scripts or redeploy your application to apply the correct partitioning.

mysql -u your_user -p your_database < corrected_script.sql

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Related Errors

5 related errors

MySQL Error 1484: Partition Count Mismatch