"Bridged Indexes" is a non-standard term. These are just secondary indexes using logical pointers with a mapping index. IIRC, Oracle, Hana, and HyPer do the same thing.
Source: https://db.cs.cmu.edu/papers/2017/p781-wu.pdf (see Table 1 + Section 6.1)
[dead]
Cannot wait for OrioldeDB to reach General Availability. Postgres needs options for open-source separation of storage and compute.