Polardb Daily Check

PolarDB Daily Check Agent

This skill guides the agent in conducting a thorough daily health check of a PolarDB for PostgreSQL database instance. It extends the PostgreSQL daily check capabilities with PolarDB-specific checks for its unique architecture (Shared-Storage, LogIndex, HTAP/MPP).

Purpose

The primary goal of this skill is to empower the agent to proactively monitor the health and performance of PolarDB for PostgreSQL, leveraging its unique features like storage-compute separation, LogIndex, and HTAP capabilities. It performs routine inspections efficiently with PolarDB-specific insights.

Core Capabilities

The agent performs checks across several key areas:

• PolarDB Core Health: Node type verification, LogIndex status, PFS storage usage
• Availability & Health: Standard PostgreSQL health checks (invalid indexes, XID wraparound, blocking locks)
• Performance & Activity: Active sessions, long-running queries, cache efficiency, MPP parallel query performance
• HTAP & MPP: Parallel query statistics, worker status, coordinator coordination
• Storage & I/O: Shared storage performance, PolarFS usage, buffer pool status
• Replication & Consistency: Primary-readonly node sync status, LogIndex replay lag

PolarDB-Specific Checks

LogIndex Architecture

PolarDB uses LogIndex to maintain page replay history for read-only nodes, solving the "past page" problem. Key checks include:

• LogIndex replay status and latency
• WAL metadata consistency between primary and read-only nodes
• Lazy and Parallel replay efficiency

HTAP & MPP Architecture

PolarDB supports HTAP via distributed MPP execution engine:

• PxScan and Shuffle operators for parallel execution
• Coordinator-Worker coordination for skew elimination
• Serverless elastic scaling of compute nodes
• polar_enable_px parameter controls MPP functionality

Storage-Compute Separation

In this architecture:

• Storage: Shared PolarFS, scales independently
• Compute: Multiple read-write and read-only nodes, stateless
• Benefits: No data replication during scaling, cost-effective read replicas

Workflow

When activated, this skill executes a predefined sequence of checks:

1. First runs PolarDB-specific checks (node type, LogIndex, PFS)
2. Then runs standard PostgreSQL compatibility checks
3. Generates a comprehensive Markdown report with PolarDB-specific recommendations

Available Skills

Each item below represents a callable skill, returning structured JSON output.

1. PolarDB Core Health

Skill: get_polar_node_type

• Description: Checks the current PolarDB node type and role using polar_node_type() function.
• Usage: ./run_polardb_check.sh get_polar_node_type
• Expected Output:

  {
    "skill": "get_polar_node_type",
    "status": "success",
    "data": [
      {
        "node_type": "Primary",
        "is_writable": true,
        "polar_version": "2.0"
      }
    ]
  }
  

• Analysis: Reports the node role (Primary/ReadOnly) and write capability.

Skill: get_logindex_status

• Description: Monitors LogIndex replay status and lag between primary and read-only nodes.
• Usage: ./run_polardb_check.sh get_logindex_status
• Expected Output:

  {
    "skill": "get_logindex_status",
    "status": "success",
    "data": [
      {
        "node_role": "ReadOnly",
        "replay_lag_mb": 15,
        "replay_lag_seconds": 2,
        "pending_wal_count": 50
      }
    ]
  }
  

• Analysis: WARNING if replay lag >100MB or >10 seconds. CRITICAL if lag >1GB.

Skill: get_pfs_usage

• Description: Reports Polar File System (PFS) storage usage using pfs_du_with_depth() and pfs_info().
• Usage: ./run_polardb_check.sh get_pfs_usage
• Expected Output:

  {
    "skill": "get_pfs_usage",
    "status": "success",
    "data": [
      {
        "total_size_gb": 500,
        "used_size_gb": 350,
        "used_percentage": 70,
        "file_count": 15000
      }
    ]
  }
  

• Analysis: WARNING if usage >80%, CRITICAL if >90%.

Skill: get_polar_process_status

• Description: Detailed process information using polar_stat_process() - PID, wait events, I/O stats, CPU, RSS.
• Usage: ./run_polardb_check.sh get_polar_process_status
• Expected Output:

  {
    "skill": "get_polar_process_status",
    "status": "success",
    "data": [
      {
        "pid": 1234,
        "state": "active",
        "wait_event": "ClientRead",
        "cpu_user": 5.2,
        "cpu_system": 1.5,
        "rss_mb": 2048,
        "shared_storage_read_iops": 150,
        "shared_storage_read_throughput_mbps": 50,
        "shared_storage_read_latency_ms": 0.5
      }
    ]
  }
  

• Analysis: Reports detailed resource utilization per process.

Skill: get_polar_activity

• Description: Enhanced activity view combining pg_stat_activity and polar_stat_process().
• Usage: ./run_polardb_check.sh get_polar_activity
• Expected Output:

  {
    "skill": "get_polar_activity",
    "status": "success",
    "data": [
      {
        "pid": 1234,
        "usename": "app_user",
        "state": "active",
        "query": "SELECT * FROM orders WHERE...",
        "duration": "00:00:05",
        "wait_event": "IO polarfs",
        "shared_io": true
      }
    ]
  }
  

• Analysis: Enhanced monitoring with PolarDB-specific wait events.

2. HTAP & MPP Checks

Skill: get_px_workers_status

• Description: Checks MPP parallel query worker status and configuration.
• Usage: ./run_polardb_check.sh get_px_workers_status
• Expected Output:

  {
    "skill": "get_px_workers_status",
    "status": "success",
    "data": [
      {
        "polar_enable_px": true,
        "polar_px_max_workers_number": 64,
        "polar_px_dop_per_node": 8,
        "active_px_queries": 3,
        "total_px_workers": 24
      }
    ]
  }
  

• Analysis: Reports MPP configuration and active parallel queries.

Skill: get_px_query_stats

• Description: Statistics on MPP parallel query execution and performance.
• Usage: ./run_polardb_check.sh get_px_query_stats
• Expected Output:

  {
    "skill": "get_px_query_stats",
    "status": "success",
    "data": [
      {
        "query_type": "PxScan",
        "execution_count": 1500,
        "avg_execution_time_ms": 45,
        "total_rows_scanned": 5000000000
      }
    ]
  }
  

• Analysis: Monitors HTAP workload performance.

Skill: get_px_nodes

• Description: Lists nodes participating in MPP execution via polar_px_nodes.
• Usage: ./run_polardb_check.sh get_px_nodes
• Expected Output:

  {
    "skill": "get_px_nodes",
    "status": "success",
    "data": [
      {"node_id": 1, "node_name": "primary", "is_coordinator": true},
      {"node_id": 2, "node_name": "readonly1", "is_worker": true},
      {"node_id": 3, "node_name": "readonly2", "is_worker": true}
    ]
  }
  

• Analysis: Shows MPP cluster topology.

Skill: get_buffer_pool_affinity

• Description: Checks Buffer Pool affinity settings and effectiveness for MPP operations.
• Usage: ./run_polardb_check.sh get_buffer_pool_affinity
• Expected Output:

  {
    "skill": "get_buffer_pool_affinity",
    "status": "success",
    "data": [
      {
        "buffer_hit_ratio": 99.5,
        "local_buffer_usage": 80,
        "shared_buffer_usage": 75
      }
    ]
  }
  

• Analysis: Reports buffer efficiency for shared storage access.

3. Storage & I/O Performance

Skill: get_shared_storage_stats

• Description: Shared storage I/O performance metrics (IOPS, throughput, latency).
• Usage: ./run_polardb_check.sh get_shared_storage_stats
• Expected Output:

  {
    "skill": "get_shared_storage_stats",
    "status": "success",
    "data": [
      {
        "read_iops": 5000,
        "write_iops": 2000,
        "read_throughput_mbps": 200,
        "write_throughput_mbps": 100,
        "read_latency_ms": 0.3,
        "write_latency_ms": 0.5
      }
    ]
  }
  

• Analysis: WARNING if latency >5ms, CRITICAL if >10ms.

Skill: get_polar_io_stats

• Description: Detailed I/O statistics from PolarDB-specific monitoring.
• Usage: ./run_polardb_check.sh get_polar_io_stats
• Expected Output:

  {
    "skill": "get_polar_io_stats",
    "status": "success",
    "data": [
      {
        "polarfs_read_count": 1000000,
        "polarfs_write_count": 500000,
        "polarfs_read_bytes": "50 GB",
        "polarfs_write_bytes": "25 GB",
        "polarfs_iops": 8000,
        "polarfs_throughput_mbps": 350
      }
    ]
  }
  

• Analysis: Detailed PolarFS I/O patterns.

Skill: get_dirty_page_status

• Description: Dirty page flush status and coordination with read-only nodes.
• Usage: ./run_polardb_check.sh get_dirty_page_status
• Expected Output:

  {
    "skill": "get_dirty_page_status",
    "status": "success",
    "data": [
      {
        "dirty_pages_count": 5000,
        "dirty_bytes_mb": 200,
        "flush_rate_pages_per_sec": 1000,
        "oldest_modified_age": 120
      }
    ]
  }
  

• Analysis: Monitors primary node dirty page flushing coordination.

4. High Availability & Consistency

Skill: get_primary_readonly_sync

• Description: Synchronization status between primary and read-only nodes.
• Usage: ./run_polardb_check.sh get_primary_readonly_sync
• Expected Output:

  {
    "skill": "get_primary_readonly_sync",
    "status": "success",
    "data": [
      {
        "primary_node": "node_primary",
        "readonly_nodes": [
          {
            "node_name": "node_readonly1",
            "sync_status": "streaming",
            "lag_bytes": 5242880,
            "lag_seconds": 1.5
          }
        ]
      }
    ]
  }
  

• Analysis: CRITICAL if any node not in streaming status.

Skill: get_online_promote_status

• Description: Checks readiness for online promotion capability.
• Usage: ./run_polardb_check.sh get_online_promote_status
• Expected Output:

  {
    "skill": "get_online_promote_status",
    "status": "success",
    "data": [
      {
        "promote_ready": true,
        "last_promote_time": "2024-01-15 10:30:00",
        "promote_in_progress": false
      }
    ]
  }
  

• Analysis: Reports online promotion readiness.

Skill: get_recovery_progress

• Description: Recovery progress for read-only nodes (if applicable).
• Usage: ./run_polardb_check.sh get_recovery_progress
• Expected Output:

  {
    "skill": "get_recovery_progress",
    "status": "success",
    "data": [
      {
        "node_name": "node_readonly1",
        "received_lsn": "0/ABCDEF00",
        "replayed_lsn": "0/ABCDE800",
        "replay_lag_bytes": 256,
        "is_applying": true
      }
    ]
  }
  

• Analysis: Monitors WAL replay progress.

5. PostgreSQL Compatibility Checks

The following skills are identical to the standard PostgreSQL daily check and work seamlessly with PolarDB.

Availability & Health

Session & Connection Monitoring

Performance & Activity

Replication & Archiving

Maintenance & Storage

Freeze & Wraparound Protection

Environment Setup

Requirements

• psql command-line tool (PostgreSQL client, version 10+)
• Python 3.6+ (uses only standard library, no additional packages)
• polar_monitor extension installed and available
• Read access to PolarDB-specific functions

Configuration

Configure database connection in assets/db_config.env:

export PGHOST="127.0.0.1"
export PGPORT="5432"
export PGUSER="digoal"
export PGPASSWORD="your_password"
export PGDATABASE="postgres"

Required Extensions

Ensure the following extensions are available:

• polar_monitor - Core PolarDB monitoring functions
• pg_stat_statements - SQL performance statistics (optional)
• pg_buffercache - Buffer pool analysis (optional)

Installation Check

Verify PolarDB extensions are installed:

SELECT * FROM pg_extension WHERE extname LIKE 'polar%';
SELECT * FROM pg_extension WHERE extname = 'pg_stat_statements';

Usage

Run Full Health Check

cd polardb-daily-check/scripts

# Run full health check (generates polar_daily_health_report.md)
python3 polardb_agent.py

# Or run via the bash wrapper
./run_polardb_check.sh full_check

Run Individual PolarDB-Specific Checks

./run_polardb_check.sh get_polar_node_type
./run_polardb_check.sh get_logindex_status
./run_polardb_check.sh get_pfs_usage
./run_polardb_check.sh get_px_workers_status
./run_polardb_check.sh get_shared_storage_stats

Run Standard PostgreSQL Compatibility Checks

./run_polardb_check.sh get_long_running_queries
./run_polardb_check.sh get_table_bloat
./run_polardb_check.sh get_replication_status
./run_polardb_check.sh get_cache_hit_rate

Output

PolarDB Daily Health Report

The agent generates polar_daily_health_report.md with:

1. PolarDB-Specific Status

   • Node type and role
   • LogIndex replay lag
   • PFS storage usage
   • MPP/HTAP status

2. Overall Health Status

   • OK / WARNING / CRITICAL

3. Detailed Findings

   • PolarDB-specific issues
   • Standard PostgreSQL issues
   • Performance recommendations

4. Actionable Recommendations

   • LogIndex optimization
   • MPP tuning suggestions
   • Storage capacity planning
   • High availability readiness

Sample Report Structure

# PolarDB Daily Health Report
Generated: 2024-01-15 10:00:00

## PolarDB Status
- Node Type: Primary (Writable)
- LogIndex Lag: 5MB (2s) ✅ OK
- PFS Usage: 70% ✅ OK
- MPP Enabled: true ✅ OK

## Overall Status: ✅ HEALTHY

### Critical Issues
None

### Warnings
- 3 long-running queries detected
- Table 'orders' has 15% bloat

### Recommendations
1. Consider running VACUUM FULL on 'orders' table
2. Review slow queries in pg_stat_statements

PolarDB-Specific Recommendations

LogIndex Optimization

• Monitor replay lag continuously
• If lag increases, check:
  • Network bandwidth between compute and storage
  • Storage I/O performance
  • Read-only node workload

MPP Tuning

• Adjust polar_px_max_workers_number based on workload
• Use ALTER TABLE ... SET(px_workers=...) for large tables only
• Monitor polar_px_dop_per_node for parallel degree

Storage Capacity

• Plan for 70% PFS usage threshold
• Consider storage tiering for cold data
• Monitor I/O latency for performance degradation

High Availability

• Test online promotion periodically
• Monitor sync lag between nodes
• Keep polar_enable_px consistent across nodes

Skill Index

PolarDB Core Health

HTAP & MPP

Storage & I/O

High Availability

PostgreSQL Compatibility

Notes

This skill is designed for PolarDB for PostgreSQL and requires the polar_monitor extension. Standard PostgreSQL checks work on both PolarDB and regular PostgreSQL instances.

For more information about PolarDB architecture:

• PolarDB Architecture Overview
• PolarDB HTAP Architecture
• PolarDB Operations Guide

Base directory for this skill: file:///Users/digoal/.config/opencode/skills/polardb-daily-check Relative paths in this skill (e.g., scripts/, assets/) are relative to this base directory.