Deduplication over the last 24 hours

1. What is the maximum deduplication duration for commands submitted to a Participant Node on Canton for Postgres?

2. If I want to ensure uniqueness of requests (assuming a request is uniquely identified by a combination of client ID & request ID) received over the last 24 hours, what is the recommended approach? Can I use command deduplication for that with either duplication duration or duplication offset, or do I have to use Contract Keys to prevent duplicate requests?

You can configure the maximum deduplication period per participant: https://docs.daml.com/2.3.4/canton/scaladoc/com/digitalasset/canton/participant/config/LedgerApiServerConfig.html

The default is 7 days. So using the deduplication feature for 24 hours should work by default.