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Stored relations and transactions
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The first thing to know before we get into the topic is that you can execute multiple queries in one go,
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by wrapping each query in curly braces ``{}``. Each query can have its own independent query options.
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Execution proceeds for each query serially, and aborts at the first error encountered.
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The returned relation is that of the last query.
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Multiple queries passed in one go are executed in a single transaction. Within the transaction,
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execution of queries adheres to multi-version concurrency control: only data that are already committed,
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or written within the same transaction, are read,
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and at the end of the transaction any changes to stored relations are only committed if there are no conflicts
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and no errors are raised.
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Using stored relations
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Chaining queries into a single transaction
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Using transaction to make indices
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