Implement Per-Transaction Buffer Pinning Limit to Prevent Buffer Pool Monopolization

[JyotinderSingh]

To prevent a single transaction from monopolizing the entire buffer pool, implement a mechanism that limits the number of buffers each transaction can pin. This will prevent rogue clients from exhausting buffer resources, improving system fairness and ensuring better availability for other transactions.

Proposed Solution

1. Define a Per-Transaction Buffer Limit: Set a configurable maximum percentage of the buffer pool that a single transaction can pin.
2. Enforce Limit During Buffer Pinning: Modify the buffer management logic to check each transaction’s current buffer usage against the defined limit before allowing it to pin additional buffers.

Benefits

1. Improved Fairness: Ensures that no single transaction can monopolize buffer resources, allowing multiple transactions to progress simultaneously.
2. Increased System Stability: Prevents transaction starvation by maintaining buffer availability, reducing the risk of prolonged waits or deadlocks.
3. Predictable Performance: Helps maintain more consistent response times across transactions, even under high-load scenarios.

Potential Challenges

1. Handling Complex Transactions: Some legitimate transactions might require a high number of buffers due to complex operations. A strict limit could hinder their performance.
2. Increased Management Complexity: Implementing and enforcing buffer limits adds overhead to buffer management, and may require additional tracking per transaction.
3. Deadlock Potential: Imposing limits may increase the risk of deadlock if multiple transactions are waiting on buffers held by others.

Alternative Solutions

1. Priority-Based Buffer Allocation: Allow certain high-priority transactions to exceed the standard buffer limit when necessary.
2. Adaptive Limit Adjustment: Adjust buffer limits dynamically based on workload and resource availability.