Read Returns Latest Write - Isolation Anomalies

Reads observe the latest visible write in the trace model.

highlighted = computed this step

A read returns the latest write

The isolation model executes a trace from top to bottom. A read observes the latest visible write so far, including uncommitted writes. Note: the render annotates each read with its recomputed value.

\text{latest write model}

Visible value

The compiled trace has 1 read and 1 final-state item. Note: the numeric value itself appears only in the render.

\text{reads}=1,\quad \text{final items}=1

these traces model specific anomalies under a read-latest-write execution model; isolation levels (RC/RR/SI/serializable) and MVCC mechanism are modelled later - no product claims.

Summary

This book follows one read-latest-write trace model so anomalies can be seen directly. Note: isolation levels, serializable behavior, and MVCC mechanisms are deferred to later books.

\text{read latest write}