[jhealy]

I'm not the author but I work at the same company.

None of our systems require perfect ordering of IDs generated across our distributed system. Most of the system was built with random UUIDv4 identifiers so no code assumes the ID ordering is significant.

However, in much of our system recent data is frequently accessed while old data is rarely accessed. In that world, just having the IDs *approximately* clustered in creation order has been a huge performance boost for many queries, and we've seen significant reduction in postgres Write Ahead Log rates, because writes to UID indexes happen in a smaller number of pages.

[sgarland]

> In that world, just having the IDs approximately clustered in creation order has been a huge performance boost for many queries, and we've seen significant reduction in postgres Write Ahead Log rates, because writes to UID indexes happen in a smaller number of pages.

Thank you. I’m so tired of seeing the same groupthink on UUIDv4 trotted out - “it only matters if you have a clustered index, Postgres is immune!” The hell it is.

[XCSme]

Just curious, if there is no ordering of the data (no sequential ID), how is it even "ordered" on the file system? Is it random? Or, even without a sequential ID can you know which data was written earlier and which later?