We definitely should make that clearer in the docs (thanks for highlighting this). The Postgres image used is Postgres 17.

On the parameters, the relational tests use 5 million records per test. The exceptions are the key-value category, which uses 15 million records, and the embedded category, which uses 1 million records. The same dataset shape, workload, harness, and hardware are used across the engines being compared.

For WAL, the 2 to 16 GB range is not intended to be a limit based on the dataset size. For the published runs, the dataset is small enough that this should not be a bottleneck. The persistent runs are also full-durability runs, with Postgres using fsync and synchronous_commit.

We will update the benchmarks page so the versions, dataset sizes, and tuning details are easier to find without digging through the Rust source.