Sure, you can do that, but that does not mean that your transactions will actually be relayed across the network. Just because you have this in your config does not mean that your peers will so they likely won't accept any transactions once you reach the default limit. Your local config only applies to your node. Changing this just means the transactions will sit in your node's mempool (and not be relayed across the network). They won't even be rebroadcast by your node because nodes don't do that.
Tank you for the explanation. I understand.
If I override the default limit , this applies only to my node.
Instead of trying to get long unconfirmed transaction chains to be relayed, you should be rethinking why you are generating long unconfirmed transaction chains and thinking of ways that you can avoid making long unconfirmed transaction chains instead.
Thank you for your advice. I will try to improve it.
No need to do that. This has nothing to do with the databases.
Does this means that there is no need for adding reindex options ?
2. Restart bitcoind (← without adding -reindex options)