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Database / Mnesia intermediate to advanced Interview questions

What is the {majority, true} table option and what tradeoff does it introduce?

Setting {majority, true} on a table requires that a write be acknowledged by a majority of the nodes holding a copy of that table before the transaction is allowed to commit — if a network partition leaves a node (or minority group of nodes) unable to reach a majority of replicas, writes on that isolated side are refused rather than silently accepted.

mnesia:create_table(critical_config,
    [{disc_copies, [n1, n2, n3]},
     {majority, true},
     {attributes, [key, value]}]).

This directly trades availability for consistency during a partition: the minority side can't write at all until connectivity is restored, whereas without the option, both sides of a partition could keep accepting (potentially conflicting) writes independently. It's the closest thing Mnesia offers to a quorum-based consistency guarantee, at the cost of write availability on whichever side of a split doesn't hold a majority.

What does {majority, true} require before a write can commit?
What tradeoff does the majority option introduce during a network partition?

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