Query Scheduler

Overview

Priority-based query scheduling system for optimizing resource utilization and meeting SLAs.

Planned Features

• Priority Scheduling: Multi-level priority queue (High/Medium/Low)
• Fair Queuing: Prevent starvation of low-priority queries
• Preemption: Ability to pause/resume long-running queries
• SLA-Based Scheduling: Prioritize queries to meet SLA targets
• Workload-Aware Scheduling: OLTP vs OLAP vs Batch differentiation

Architecture (Planned)

Query Admission → Scheduler → [High/Med/Low Priority Queues]
                       ↓
                  Executor Pool (Dynamic)
                       ↓
                  Resource Monitor

Scheduling Policies (Draft)

1. FIFO: First-in-first-out (default for same priority)
2. Shortest Job First: Prioritize fast queries
3. Fair Share: Equal CPU/memory allocation per tenant
4. SLA-Driven: Prioritize queries at risk of SLA violation

Configuration (Draft)

query_scheduler:
  policy: sla_driven
  priorities:
    - level: high
      max_concurrent: 100
      timeout_ms: 5000
    - level: medium
      max_concurrent: 200
      timeout_ms: 30000
    - level: low
      max_concurrent: 50
      timeout_ms: 300000

Related Documentation

• Graceful Degradation
• Admission Control
• Resource Manager

Status: Planned (roadmap). The features, architecture and configuration on this page describe the planned design.