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Description

MySQL Error 1736, 'Tables have different definitions', indicates a structural inconsistency between two tables or a table and its expected schema. This error commonly arises during replication, DDL operations, or when the database attempts to compare or synchronize table metadata, signaling a fundamental mismatch in how tables are defined.

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Error Message

Tables have different definitions

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Known Causes

4 known causes

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Replication Schema Drift

Occurs when a replica server's table schema differs from its master, causing inconsistencies during replication events or data synchronization.

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Incomplete ALTER TABLE

An `ALTER TABLE` statement might have failed or been interrupted, leaving the table in an inconsistent state where its on-disk definition doesn't match its internal metadata.

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Metadata Corruption

Internal MySQL system tables or `.frm` files (table definition files) might be corrupted, leading MySQL to perceive tables as having mismatched definitions.

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Version/Engine Incompatibility

Using different MySQL versions or storage engines across instances (e.g., master/slave) can sometimes lead to definition discrepancies, especially with complex DDL changes.

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Solutions

3 solutions available

1. Synchronize Table Definitions with `ALTER TABLE` medium

Manually align the structure of the mismatched tables.

1

Identify the differences between the table definitions. You can do this by comparing `SHOW CREATE TABLE table_name;` output for both tables.

SHOW CREATE TABLE table1;
SHOW CREATE TABLE table2;

2

Based on the identified differences, use `ALTER TABLE` statements to modify one of the tables to match the other. Choose the definition you want to enforce.

-- Example: If table2 is missing a column that table1 has:
ALTER TABLE table2 ADD COLUMN new_column INT;

-- Example: If a column in table2 has a different data type than in table1:
ALTER TABLE table2 MODIFY COLUMN existing_column VARCHAR(255);

-- Example: If table1 has an index that table2 is missing:
ALTER TABLE table2 ADD INDEX index_name (column_name);

3

Repeat the `SHOW CREATE TABLE` comparison and `ALTER TABLE` modifications until both tables have identical definitions.

SHOW CREATE TABLE table1;
SHOW CREATE TABLE table2;

2. Replicate Table Structure from a Master Copy easy

Drop and recreate a table based on a known correct definition.

1

Identify a table with the correct definition. This might be the original table or a reference table.

SELECT 'This is the table with the correct definition.';

2

Backup any data that might be in the incorrect table (if necessary).

-- Example: Exporting data to a CSV file
SELECT * INTO OUTFILE '/path/to/backup/table_name.csv' FIELDS TERMINATED BY ',' ENCLOSED BY '"' LINES TERMINATED BY '\n' FROM table_name;

3

Drop the table with the incorrect definition.

DROP TABLE table_name_with_incorrect_definition;

4

Recreate the table using the `CREATE TABLE` statement from the master copy. You can obtain this using `SHOW CREATE TABLE master_table_name;`.

-- Get the create statement from the correct table
SHOW CREATE TABLE master_table_name;

-- Use the output to create the new table
CREATE TABLE table_name_with_incorrect_definition (
    -- columns and constraints from master_table_name
);

5

If you backed up data, re-import it into the newly created table.

-- Example: Importing data from a CSV file
LOAD DATA INFILE '/path/to/backup/table_name.csv' INTO TABLE table_name_with_incorrect_definition FIELDS TERMINATED BY ',' ENCLOSED BY '"' LINES TERMINATED BY '\n';

3. Utilize Database Comparison Tools medium

Automate the process of finding and synchronizing schema differences.

1

Install and configure a database comparison tool. Popular options include MySQL Workbench, Navicat, or commercial tools like Redgate SQL Compare.

## MySQL Workbench Example:
1. Open MySQL Workbench.
2. Go to 'Database' -> 'Data Export'.
3. Select the source database and the table(s) you want to compare.
4. Go to 'Database' -> 'Data Import/Restore'.
5. Choose 'Import from Self-Contained File' and select the exported file from step 3.

## Command-line tools (e.g., mysqldiff from Percona Toolkit):
1. Install Percona Toolkit.
2. Run the comparison command:
   `mysqldiff --server1=user:pass@host1:port1/db1 --server2=user:pass@host2:port2/db2 --difftype=sql --output-to-stdout`

2

Run the comparison tool to identify the schema differences between the two instances or tables.

See code snippet in step 1 for examples.

3

The tool will typically generate SQL scripts to synchronize the schemas. Review these scripts carefully.

## Example script generated by a tool:
-- Differences found:
-- Table 'your_table': Column 'id' in server1 is INT, in server2 is BIGINT
-- Table 'your_table': Missing index 'idx_name' in server2

-- Synchronization script:
ALTER TABLE your_table MODIFY COLUMN id BIGINT;
ALTER TABLE your_table ADD INDEX idx_name (column_name);

4

Execute the generated synchronization scripts on the target database (or both, depending on the tool's output).

-- Execute the SQL script generated by the comparison tool.

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Related Errors

5 related errors

MySQL Error 1736: Tables Definitions Mismatch