How should I practice Transactional In-Memory Redis?

Start by reading the full statement, solve the visible examples, then compare the pattern against related HashiCorp onsite interview problems in FastPrep.

Is Transactional In-Memory Redis associated with HashiCorp?

FastPrep tags this as a HashiCorp onsite interview coding practice problem when the problem catalog has that company and stage context.

Problem · Hash Table

Transactional In-Memory Redis

Learn this problem

● Medium

HashiCorpFULLTIMEONSITE INTERVIEW

Problem statement

Implement an in-memory key-value store with nested transactions. Process operations in order.

["ADD", key, value] stores or overwrites a string value in the current transaction level.
["DELETE", key] removes the key from the current view, including when the visible value comes from a parent level.
["GET", key] appends the visible value to the result, or NULL when the key is absent.
["BEGIN"] opens a nested transaction.
["COMMIT"] merges the current transaction's changes into its parent and closes it.
["ROLLBACK"] discards the current transaction's changes and closes it.

Only GET produces output. Every COMMIT and ROLLBACK is issued while a transaction is open.

Function

runTransactionalRedis(operations: String[][]) → String[]

Examples

Example 1

operations = [["ADD","x","1"],["BEGIN"],["ADD","x","2"],["BEGIN"],["ADD","x","3"],["COMMIT"],["GET","x"],["ROLLBACK"],["GET","x"]]return = ["3","1"]

The inner commit exposes x=3 to its parent transaction. Rolling back that parent restores the base value x=1.

Example 2

operations = [["ADD","a","base"],["BEGIN"],["DELETE","a"],["GET","a"],["BEGIN"],["ADD","a","inner"],["GET","a"],["COMMIT"],["COMMIT"],["GET","a"]]return = ["NULL","inner","inner"]

The deletion masks the base value. The nested add is committed through both open levels and becomes the final base value.

Constraints

1 <= operations.length <= 200000.
Every row has exactly the documented arity.
Keys and values are non-empty ASCII strings, and values are never NULL.
Transaction nesting depth is at most 100000.
The total length of all keys and values is at most 2000000.