I am wondering if there are no security risks if i store transaction data in a database besides the fact that is stored on the ethereum blockchain.
I am using an API to manage my smart contracts and all the transactions.
It is safe to store TX results off-chain to speed up operations with its results.
Yes it is safe to store transaction data off chain in a data base but, as data base is centralised system you will lose advantages of decentralisation which is inherent in blockchain. I will recommend to use IPFS, or ethereum swarm to strore data off-chain rather than storing it in a centralised data base server.