Final answer:
A Commit record is the log record that signifies a transaction has been successfully completed and its changes can be permanently written to the database, which is crucial for maintaining the database's ACID properties.
Step-by-step explanation:
The type of log record that indicates a transaction T has completed successfully and affirms that its effects can be committed permanently to the database is called a Commit record. The commit record serves as an essential part of the transaction management in database systems, ensuring the ACID properties (Atomicity, Consistency, Isolation, Durability) are maintained. When the system writes a commit record to the log, it signifies that all the operations of the transaction have been completed successfully and the changes can be made permanent in the database. Other types of log records include Abort records, which signal that a transaction has been rolled back, Checkpoint records, which help in reducing the recovery time during a database restart, and Undo records, which are used to reverse the changes made by a transaction that is being rolled back.