Error

Error Code: 1509

MySQL Error 1509: Invalid Partition Type for COALESCE

📦 MySQL

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Description

MySQL Error 1509 occurs when you attempt to use the `ALTER TABLE ... COALESCE PARTITION` statement on a table that is not partitioned by `HASH` or `KEY`. This operation is specifically designed to reduce the number of partitions only for tables using `HASH` or `KEY` partitioning methods.

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Error Message

COALESCE PARTITION can only be used on HASH/KEY partitions

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Known Causes

3 known causes

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Targeting Invalid Partition Type

You attempted to use `COALESCE PARTITION` on a table partitioned by methods like `RANGE` or `LIST`, which are incompatible with this operation.

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Misunderstanding COALESCE Scope

The `COALESCE PARTITION` statement was used without realizing it is exclusively designed for `HASH` or `KEY` partitioned tables to reduce their partition count.

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Unverified Script Execution

A SQL script containing `COALESCE PARTITION` was executed without prior verification of the target table's actual partitioning scheme.

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Solutions

3 solutions available

1. Switch to RANGE or LIST Partitioning advanced

Recreate the table using RANGE or LIST partitioning if COALESCE is not essential.

Identify the existing partitioning scheme and the columns used for partitioning.

SHOW CREATE TABLE your_table_name;

Back up your data. This is a critical step before making structural changes.

mysqldump -u your_user -p your_database your_table_name > your_table_name_backup.sql

Create a new table with the desired partitioning type (RANGE or LIST) and the same schema as the original table. Ensure it does NOT use COALESCE.

CREATE TABLE your_table_name_new (
    id INT PRIMARY KEY,
    data VARCHAR(255)
) PARTITION BY RANGE (id) (
    PARTITION p0 VALUES LESS THAN (100),
    PARTITION p1 VALUES LESS THAN (200)
);

Copy the data from the old table to the new table.

INSERT INTO your_table_name_new SELECT * FROM your_table_name;

Rename the old table and the new table to switch them.

RENAME TABLE your_table_name TO your_table_name_old, your_table_name_new TO your_table_name;

Verify that the new table is partitioned correctly and contains all data.

SHOW CREATE TABLE your_table_name;

Drop the old table after confirming successful migration.

DROP TABLE your_table_name_old;

2. Remove COALESCE PARTITION Clause medium

If COALESCE PARTITION is not strictly necessary, remove it from the table definition.

Examine the `CREATE TABLE` statement for the table causing the error to identify the `COALESCE PARTITION` clause.

SHOW CREATE TABLE your_table_name;

Back up your data before proceeding with structural changes.

mysqldump -u your_user -p your_database your_table_name > your_table_name_backup.sql

Recreate the table without the `COALESCE PARTITION` clause, keeping all other definitions the same.

CREATE TABLE your_table_name_new (
    id INT,
    data VARCHAR(255)
) PARTITION BY HASH(id) PARTITIONS 4;

Insert data from the original table into the new table.

INSERT INTO your_table_name_new SELECT * FROM your_table_name;

Rename the tables to replace the original with the new one.

RENAME TABLE your_table_name TO your_table_name_old, your_table_name_new TO your_table_name;

Drop the old table once you've confirmed the migration was successful.

DROP TABLE your_table_name_old;

3. Migrate to HASH or KEY Partitioning advanced

Convert the table to HASH or KEY partitioning if COALESCE is desired.

Determine the partitioning expression and the number of partitions for HASH or KEY partitioning.

SHOW CREATE TABLE your_table_name;

Perform a full backup of the table.

mysqldump -u your_user -p your_database your_table_name > your_table_name_backup.sql

Create a new table with HASH or KEY partitioning. You can use `COALESCE PARTITION` with HASH/KEY.

CREATE TABLE your_table_name_new (
    id INT,
    data VARCHAR(255)
) PARTITION BY HASH(id) COALESCE PARTITION 2;
-- Or for KEY partitioning:
-- CREATE TABLE your_table_name_new (
--     id INT,
--     data VARCHAR(255)
-- ) PARTITION BY KEY(id) COALESCE PARTITION 2;

Populate the new table with data from the original table.

INSERT INTO your_table_name_new SELECT * FROM your_table_name;

Swap the table names to make the new table live.

RENAME TABLE your_table_name TO your_table_name_old, your_table_name_new TO your_table_name;

Verify the new partitioning scheme and data integrity.

SHOW CREATE TABLE your_table_name;

Remove the old table after confirming the migration is successful.

DROP TABLE your_table_name_old;

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Related Errors

5 related errors