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  3. Transactions and Error Handling in PostgreSQL

Exercise

Isolation levels and transactions

SERIALIZABLE is an isolation level that takes a snapshot of the record when the first query or update statement is issued, and errors if the data is altered in any way outside of the transaction. Note that the transaction can do other work, such as declare variables, prior to the first query.

You'll be using the FFIEC dataset again to work with data where the annual change in savings deposits RCON0352 is affected by a large offset.

Instructions

100 XP
  • Start a transaction in SERIALIZABLE mode.
  • Update all the the records where RCON0352 is greater than 100,000 with a 50% reduction.
  • COMMIT the transaction.
  • Select the count of the records still with an RCON0352 greater than 100,000.