  The cost of using a blockchain infrastructure as well as the time required to
search and retrieve information from it must be considered when designing a
decentralized application. In this work, we examine a comprehensive set of data
management approaches for Ethereum applications and assess the associated cost
in gas as well as the retrieval performance. More precisely, we analyze the
storage and retrieval of various-sized data, utilizing smart contract storage.
In addition, we study hybrid approaches by using IPFS and Swarm as storage
platforms along with Ethereum as a timestamping proof mechanism. Such schemes
are especially effective when large chunks of data have to be managed.
Moreover, we present methods for low-cost data handling in Ethereum, namely the
event-logs, the transaction payload, and the almost surprising exploitation of
unused function arguments. Finally, we evaluate these methods on a
comprehensive set of experiments.

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