Documentation

MySQL DDL/DML Change Support

For log replication via the binary log (binlog) with MySQL, Alooma supports several types of changes to the DDL, depending on the nature of the change. Some changes are supported without any related changes to the output, some are fixable with some changes to the output, and some are not supported and thus require a reload.

Change

Description

Supported?

Add column.

Adding a non-nullable column.

Fixable/Supported by making the column nullable in the data warehouse.

Adding a nullable column - does not prevent the records from coming in, and as long as the value on the source remains null, it is supported. If the value on the source is updated, a new event will fire.

Supported.

Adding a column created with a DEFAULT value.

Not Supported.

Alter column to a new data type.

Alooma will not automatically change the column and so manual intervention might be needed to alter the column on the MySQL side. In this case, events can get stuck in the Restream Queue if they are of an old incompatible type; however, new events will load as MySQL cannot have data with an incompatible type in it.

Fixable/Supported depending on change required.

Change column to not null.

Alooma will not automatically change the column and so manual intervention is optional if you want to have the column as non-null in the target data warehouse. Events can get stuck in the Restream Queue if they have null in the non-nullable field, but new events will load as MySQL will not have nulls there now.

Manual intervention is required. Fixable/Supported.

Change column to nullable.

Alooma will not automatically change the column, and events with null values in that column will get stuck in the Restream Queue until the column is made nullable in the target data warehouse. No new events will load.

Requires changes to output. Fixable/Supported.

Drop column from the middle of the table.

The events may get corrupted (all of the fields shifted over one column). In this case a manual re-dump of the data is required.

Not Supported.

Drop column from the end of the table.

No issues as extraneous data will be ignored.

Supported.

Cascading Delete.

Not Supported.

Truncation.

When using row format, truncate operations do not come through the binlog in the same manner as they would for a MySQL host.

Not Supported.

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