Repetition and definition levels are a method used to convert structural arrays into buffers, popularized by Parquet and differing from approaches used in Arrow, which employs validity and offsets buffers. This method impacts I/O patterns by providing an alternative encoding that is naturally compressed, potentially offering advantages in random access and data compactness. Repetition levels replace offsets by using single buffers that signify the start and continuation of lists, while definition levels replace validity buffers, simplifying the determination of nulls by consolidating multiple validity buffers into a single, more efficient buffer. Although this approach allows for data to be zipped together and offers a single source of logical truth, it requires conversion to revert to Arrow format, making it not "zero copy." These techniques are crucial for projects like Lance, which benefit from reduced buffer numbers for random access, although the absence of an offsets buffer presents a challenge. Future exploration will focus on structural encoding to balance CPU costs and random access performance further, in line with LanceDB's innovations in modern data lake technologies.