- * There are three types of reads:
- * - READ_NORMAL : Potentially cached read of data (e.g. from a slave or stale replica)
- * - READ_LATEST : Up-to-date read as of transaction start (e.g. from master or a quorum read)
- * - READ_LOCKING : Up-to-date read as of now, that locks the records for the transaction
+ * There are four types of reads:
+ * - READ_NORMAL : Potentially cached read of data (e.g. from a slave or stale replica)
+ * - READ_LATEST : Up-to-date read as of transaction start (e.g. from master or a quorum read)
+ * - READ_LOCKING : Up-to-date read as of now, that locks (shared) the records
+ * - READ_EXCLUSIVE : Up-to-date read as of now, that locks (exclusive) the records
+ * All record locks persist for the duration of the transaction.