In a high insert throughput in a database system, the database management system (DBMS) caches, asynchronously from data insert transactions, a list of storage location identifiers for storage locations in a table space in the database system. When a request for an insert transaction with an insert size is received from an agent, the DBMS identifies a storage location on the list with an amount of free space meeting the insert size. The DBMS removes the storage location identifier from the list and returns the storage location identifier for the storage location. When the insert transaction completes, the DBMS determines a remaining free space at the storage location and adds the storage location identifier to the list according to the remaining free space. By removing storage location identifiers from the list, another agent cannot receive the same storage location identifier for a parallel task. Thus, space contention is avoided.