The "novelty retrieval" before patent application is actually called "prior art retrieval", which is different from the novelty retrieval in the general sense. The prior art search only includes the known technologies and conflicting applications before the patent application. Novelty retrieval in general also includes technologies that few people know but most people don't know (this can't be called known technologies).
There is no so-called infringement between patents. Infringement occurs between the product and the patent, but both patents may become invalid evidence of the other party.