literature review - How can I efficiently check the originality of my work?

I have worked on many ideas where I found later that they were already published, which was frustrating. I usually look around before developing my idea, but sometimes the articles I read or the keywords I use to look up any related works make me believe that my work is actually original until I find later, after skimming through hundreds of papers in the field (to further check the originality), or by a response from a reviewer that it is not the case.

In short, what's an efficient way to make sure that your work is original before developing the idea?

Edit :

Thank you for your answers. As suggested in the comments, I should have included addditional information so that the answers would make more sense.

I am a PhD student in Computer Science (CS). My main research areas are : Information theory, coding and cryptography.

Answer

Ask people

Doing literature research on your own is necessary, and you should spend some time on this to make sure that the result is not already available. But there is only so much you can find, and it often happens that the result has previously been published with a different name or title, which you could not have known about. More experienced people in the field might have come across those works and know that your result is not new.

So ask people in the field that you can trust. Your supervisor/boss/similar is usually a good start. You can also ask other people in your department. As you advance in your career, you often make new contacts with whom you can discuss such things. And, as you have experienced, peer reviewers will provide an additional "safety check".

Of course, make sure you only ask people who you can trust that they will keep your work confidential. If you are at the beginning of your career, your supervisor might provide further guidance on this.