[lia323]

Thanks!

The caption of Figure 1 lists the page size used by each system (i.e., the default configuration).

We use different page sizes across systems, and as you said, it is a bit difficult to compare them directly apples-to-apples. This is actually intentional! Because this also exposes the B-tree index-level write amplification effects. In that sense, Figure 1 kind of suggests that larger page sizes may not necessarily be great for write amplification.

And yes, you are correct regarding Postgres. Instead of having a separate doublewrite buffer file, Postgres relies on WAL full-page writes, which indirectly trigger additional checkpoint writes, so the effect is not entirely straightforward to quantify. To explain that, we discuss how we measured DB WAF for Postgres in Section 10.7 (“How can we calculate DB WAF on other DBMSs?”) of the appendix version: https://arxiv.org/pdf/2603.09927

Regarding the WAL part, yes, the WAL itself is nicely sequential and should generally behave well on SSDs. But once it gets mixed with small random writes that are eventually persisted to flash, it will unfortunately still likely suffer from SSD WAF.