am i reading correctly that the compression is just a relational records? i.e. omit the pr title, just point to it?

There are 2 layers of compression:

- ZSTD (actual data compression)

- De-duplication (i.e. what you're saying)

Although AFAIK it's not "just point to it" but rather storing sorted data and being able to say "the next 2M rows have the same PR Title"