Isolation Levels

Stronger-Than Order

The stronger-than order is derived from strict blocked-set inclusion.

highlighted = computed this step

Stronger-than order

A level is stronger when its blocked set is a strict superset. The renderer shows only cover edges, so the order stays compact.

strict superset gives stronger than\text{strict superset gives stronger than}

Cover edges

The compiler derives 3 stronger-than cover edges across 4 comparable levels.

cover edges=3,levels=4\text{cover edges}=3,\quad \text{levels}=4

isolation levels are rendered as a tiny pedagogical matrix over named anomalies only; ANSI completeness, vendor behavior, performance, and operational guarantees are out of scope.

Stronger-than orderleveldirty_readnon_repeatable_readlost_updatewrite_skewread_committedblockedallowedallowedallowedrepeatable_readblockedblockedallowedallowedsnapshot_isolationblockedblockedblockedallowedserializableblockedblockedblockedblocked blocked versus allowedlevelblockedCountblockedallowedCountallowedread_committed1dirty_read3non_repeatable_read, lost_update, write_skewrepeatable_read2dirty_read, non_repeatable_read2lost_update, write_skewsnapshot_isolation3dirty_read, non_repeatable_read, lost_update1write_skewserializable4dirty_read, non_repeatable_read, lost_update, write_skew0none stronger-than cover edgesstrongerweakerrepeatable_readread_committedsnapshot_isolationrepeatable_readserializablesnapshot_isolation

Summary

The order is derived from blocked-set inclusion. Note: no claim is made about standards beyond this tiny matrix.

order from blocked sets\text{order from blocked sets}