An approach for caching potentially repetitive message data in a publication/subscription messaging environment is provided. Specifically, when a message is received on a broker system from a publisher system, the broker system analyzes the message for potentially repetitive data. Once such a set of data has been identified, a unique identifier/key corresponding thereto will be sent back to the publisher system and the set of data will be stored in a (data) cache. Upon receipt, the publisher system will cache/store the unique identifier in a (key) cache. Then, when the publisher system generates a future message that would contain the same set of data, the publisher system will substitute the unique identifier (as retrieved from the key cache) for the set of data to yield an abbreviated/truncated message.