An enhanced space allocation mechanism (ESAM) for dynamically allocating space for a fixed length part of variable length fields, such as VARCHAR fields, in database tables. Each record in such a variable length field has a fixed length part, a variable length part, and a pointer to the variable length part. The ESAM determines how much space to allocate based on the data that was historically put into these tables. In one embodiment, a database management system (DBMS) maintains a historical record that includes fields identifying the table, column and application ID, as well as fields that track a count and a total length. For each variable length field in a Structured Query Language (SQL) statement such as CREATE table or ALTER table, the DBMS finds a matching historical record, determines an estimated optimal fixed portion length based on the matching historical record, and sets a space allocation length for the fixed length part of the variable length field based on the estimated optimal fixed portion length. This dynamic space allocation approach is especially advantageous in situations where an empty table will be loaded with a massive amount of data.