##### Question Design a log management system that ( 1) keeps the total number of logs ≤ total_max, ( 2) automatically deletes the least important or oldest logs when adding new ones to stay within limits, and ( 3) locates logs to delete in O( 1) time using appropriate data structures (e.g., time-ordered deque plus priority heap).

This question evaluates a candidate's ability to design a bounded in-memory log buffer with prioritized eviction, testing knowledge of data structures, tie-breaking policies, time/space complexity, and deterministic handling of arrival timestamps.

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Design log management with auto-deletion | Google Interview Question

Design a Bounded Log Management System with O(1) Victim Selection

Context

You are designing an in-memory log buffer that ingests log entries and must never exceed a configured capacity (total_max). Each log has:

id (unique)
timestamp (arrival time; assume non-decreasing or we treat arrival time separately from event time)
importance (integer; lower means less important)
payload (opaque)

When the buffer is full and a new log arrives, the system should automatically evict logs to stay within capacity, preferring to remove the least important logs; ties are broken by oldest timestamp.

Requirements

Maintain total number of logs ≤ total_max at all times.
On insert, automatically delete logs to make room, preferring:
- Lowest importance first, and if there’s a tie,
- Oldest by arrival timestamp.
Locate the next log to delete in O(1) time (e.g., via a time-ordered deque and a min-priority heap). Overall update/eviction cost can exceed O(1) due to necessary re-indexing.

Deliverables

Describe the core data structures and how they interact.
Specify insertion and eviction algorithms and their time/memory complexity.
Include assumptions, tie-breaking rules, and handling of out-of-order timestamps.
Provide concise pseudocode for key operations.

Context

You are designing an in-memory log buffer that ingests log entries and must never exceed a configured capacity (total_max). Each log has:

id (unique)

timestamp (arrival time; assume non-decreasing or we treat arrival time separately from event time)

importance (integer; lower means less important)

payload (opaque)

When the buffer is full and a new log arrives, the system should automatically evict logs to stay within capacity, preferring to remove the least important logs; ties are broken by oldest timestamp.

Requirements

Maintain total number of logs ≤ total_max at all times.

On insert, automatically delete logs to make room, preferring:

Lowest importance first, and if there’s a tie,
Oldest by arrival timestamp.

Locate the next log to delete in O(1) time (e.g., via a time-ordered deque and a min-priority heap). Overall update/eviction cost can exceed O(1) due to necessary re-indexing.

Design log management with auto-deletion

Quick Overview

Design a Bounded Log Management System with O(1) Victim Selection

Context

Requirements

Deliverables

Solution

Submit Your Answer to Earn 20XP

Design log management with auto-deletion

Quick Overview

Design a Bounded Log Management System with O(1) Victim Selection

Context

Requirements

Deliverables

Solution

Submit Your Answer to Earn 20XP