Techniques are disclosed relating to efficiently processing of concurrent database transactions. In one embodiment, a database system receives a first key-value pair for a database transaction and stores the key-value pair in a data structure for active database transactions. The storing may include indexing into a hash table of the data structure with a key of the key-value pair to identify a hash bucket of the hash table corresponding to the key, acquiring a latch associated with the identified hash bucket, and, based on a state of the acquired latch, appending, to the hash bucket, a record specifying the key-value pair. The database system may cause the key-value pair from the data structure to be committed to persistent storage in response to the database transaction being committed.