[masklinn]

> Why uuid7, is the btree performance better with it than with uuid4?

Yes, being ordered uuid7 leads to less splitting and index bloat than the fully random uuid4. So while the lookup is pretty similar the index is in much better shape.

And if lookup is correlated with recency (which is probably the case for most record types) recent entries will be grouped together on the same pages in the uuid7 index leading to better cache presence, whereas in a uuid4 index they’ll be randomly spread over the entire index set.