How can a standby read read transaction see a transient state?

Question

In the PostgreSQL documentation on transaction isolation levels, we can read the following:

When performing all records of a persistent database as part of Serializable Transactions on the main server, make sure that all backups eventually reach a consistent state, a read-standby transaction can sometimes see a transient state that is incompatible with any sequential execution of serializable transactions on the master .

The above text is at the bottom of http://www.postgresql.org/docs/9.4/static/transaction-iso.html

In what circumstances could a repeat read transaction in standby mode see an inconsistent transient state?

Answer 1

The answer from Geir Bostad is correct; I answer only to give an example and a possible workaround, as people often do not have enough heads. In addition to the Wiki page referenced by another answer, there is a separate Wiki page for an example that includes the “Deposit Report Example” , seeing the package as closed, but not yet able to see the final part for the batch.

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Answer 2

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