A new Jepsen report! It turns out that PostgreSQL's "serializable" isolation was not, in fact, serializable: it exhibited G2-item. A patch is coming in the next minor release. :) http://jepsen.io/analyses/postgresql-12.3
Something odd came up during this review, which Martin Kleppmman previously reported in https://github.com/ept/hermitage/blob/master/postgres.md: PostgreSQL repeatable read isn't repeatable read: it's snapshot isolation, which allows a specific class of G2-item anomalies (those with nonadjacent rw edges) prohibited under formalizations of repeatable read.
So, while Berenson et al. say that snapshot isolation isn't stronger than repeatable read, PostgreSQL appears to have implicitly adopted the strict interpretation instead, and says that SI is stronger than RR. In fact, SI prohibits *every* anomaly in the strict interpretation of the ANSI SQL standard, including their (narrow) definition of phantoms!
Anyway, consistency models are a mess; news at 11. 😂
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