Each “extra” column in the version of the table having more columns must have a default value.

Matching columns must be defined in the same order on both the master and the slave.

Any additional columns must be defined following the matching columns.

More columns on the master.  The following table definitions are valid:

master> CREATE TABLE t1 (c1 INT, c2 INT, c3 INT);
slave>  CREATE TABLE t1 (c1 INT, c2 INT);

The following table definitions would raise Error 1532 (ER_BINLOG_ROW_RBR_TO_SBR) because the definitions of the columns common to both versions of the table are in a different order on the slave than they are on the master:

master> CREATE TABLE t1 (c1 INT, c2 INT, c3 INT);
slave>  CREATE TABLE t1 (c2 INT, c1 INT);

The following table definitions would also raise Error 1532, because the definition of the extra column on the master appears before the definitions of the columns common to both versions of the table:

master> CREATE TABLE t1 (c3 INT, c1 INT, c2 INT);
slave>  CREATE TABLE t1 (c1 INT, c2 INT);

More columns on the slave.  The following definitions replicate correctly:

master> CREATE TABLE t1 (c1 INT, c2 INT);
slave>  CREATE TABLE t1 (c1 INT, c2 INT, c3 INT);
                  

The following definitions raise Error 1532 because the columns common to both versions of the table are not defined in the same order on both the master and the slave:

master> CREATE TABLE t1 (c1 INT, c2 INT);
slave>  CREATE TABLE t1 (c2 INT, c1 INT, c3 INT);

The following table definitions also raise Error 1532 because the definition for the extra column in the slave's version of the table appears before the definitions for the columns which are common to both versions of the table:

master> CREATE TABLE t1 (c1 INT, c2 INT);
slave>  CREATE TABLE t1 (c3 INT, c1 INT, c2 INT);

The following table definitions fail, because the slave's version of the table has additional columns compared to the master's version, and the two versions of the table define column c2 as a different data type.

master> CREATE TABLE t1 (c1 INT, c2 BIGINT);
slave>  CREATE TABLE t1 (c1 INT, c2 INT, c3 INT);

The slave's copy of the table cannot contain more columns than the master's copy.

For columns holding numeric data types, the sizes may differ, as long as the size of the slave's version of the column is equal or greater to the size of the master's version of the column. This is sometimes referred to as attribute promotion, because the data type of the master's version of the column is promoted to a type that is the same size or larger on the slave.

Data type conversions currently supported by attribute promotion are shown in the following table, in which X and N both represent positive integers.

Unsigned integer columns can be promoted to larger unsigned types; for example, a column declared as TINYINT UNSIGNED can be restored to a column declared as SMALLINT UNSIGNED, MEDIUMINT UNSIGNED, INT UNSIGNED, or BIGINT UNSIGNED. You cannot promote a signed column to an unsigned type, or an unsigned column to a signed type.

For columns holding numeric data types the sizes may differ, as long as the size of the slave's version of the column is equal or greater to the size of the master's version of the column. For example, the following table definitions are allowed:

master> CREATE TABLE t1 (c1 TINYINT, c2 INT);
slave>  CREATE TABLE t1 (c1 INT,     c2 INT);

The slave's versions of both columns c1 and c2 are the same size as or larger than the master's versions of these columns. However, the following definitions would fail:

master> CREATE TABLE t1 (c1 INT, c2 FLOAT(8,3));
slave>  CREATE TABLE t1 (c1 INT, c2 FLOAT(7,3));

In this case, Error 1532 would be raised because the master's copy of column c2 is larger than its counterpart on the slave — that is, the master's copy of c2 on the master can hold more digits than the slave's copy of the column.

There is no conversion between integer (TINYINT, SMALLINT, MEDIUMINT, and so on) and noninteger (FLOAT, DOUBLE, DECIMAL, and so on) numeric data types, and so the following definitions would fail with Error 1532:

master> CREATE TABLE t1 (c1 INT, c2 FLOAT(8,3));
slave>  CREATE TABLE t1 (c1 INT, c2 BIGINT);

A column using a noninteger numeric data type must always have the same definition on both the master and the slave.

For columns storing CHAR and BINARY data, the size of the slave's copy of the column must be equal to or greater than the size of the master's copy. For example, the following table definitions would replicate successfully:

master> CREATE TABLE t1 (c1 INT, c2 CHAR(30));
slave>  CREATE TABLE t1 (c1 INT, c2 CHAR(50));

If the size of the master's version of the column is greater than that of the slave's version of the column, replication fails with Error 1532.

The replication process can convert freely between BINARY, VARBINARY, CHAR and VARCHAR columns, as long as the slave's version of the column is the same size as or larger than the master's version. For example, the following table definitions can be used successfully:

master> CREATE TABLE t1 (c1 INT, c2 VARBINARY(30));
slave>  CREATE TABLE t1 (c1 INT, c2 CHAR(30));

Attribute promotion can be used with both statement-based and row-based replication, and is not dependent on the storage engine used by either the master or the slave.