STD_EXCEPTION ClickHouse error¶

The STD_EXCEPTION error in ClickHouse (and Tinybird) is a generic exception that can occur for various reasons. It's a catch-all error that typically indicates an internal ClickHouse issue, system problem, or unexpected condition that doesn't fit into more specific error categories. This error requires investigation to determine the root cause.

What causes this error¶

You'll typically see it when:

• Internal ClickHouse system errors
• Memory allocation failures
• File system issues
• Network communication problems
• Corrupted data or indexes
• System resource exhaustion
• Unexpected data format issues
• Internal ClickHouse bugs or edge cases

Example errors¶

SELECT * FROM events WHERE timestamp > '2024-01-01'
-- Returns STD_EXCEPTION due to internal system issue

SELECT COUNT(DISTINCT user_id) FROM very_large_table
-- Returns STD_EXCEPTION due to memory constraints

INSERT INTO events (user_id, event_type, timestamp) VALUES
(123, 'click', '2024-01-01 10:00:00')
-- Returns STD_EXCEPTION due to disk space or file corruption

SELECT * FROM corrupted_table
-- Returns STD_EXCEPTION due to data corruption

How to fix it¶

Check system resources¶

Verify system health and resources:

SELECT
    name,
    value,
    description
FROM system.settings
WHERE name IN ('max_memory_usage', 'max_bytes_before_external_group_by', 'max_bytes_before_external_sort')

Verify table integrity¶

Check if tables are corrupted:

SELECT
    database,
    table,
    partition,
    name,
    rows,
    bytes_on_disk
FROM system.parts
WHERE active = 1
ORDER BY bytes_on_disk DESC

Check system logs¶

Look for error patterns in system logs:

SELECT
    event_time,
    event_type,
    message
FROM system.text_log
WHERE event_type = 'ErrorLog'
ORDER BY event_time DESC
LIMIT 100

Restart problematic operations¶

Try restarting the operation:

-- Instead of processing all data at once
SELECT COUNT(*) FROM events WHERE timestamp >= '2024-01-01'

-- Try with smaller time ranges
SELECT COUNT(*) FROM events WHERE timestamp >= '2024-01-01' AND timestamp < '2024-01-02'

Common patterns and solutions¶

Memory-related issues¶

Handle memory constraints:

-- Set memory limits
SET max_memory_usage = 10000000000; -- 10GB
SET max_bytes_before_external_group_by = 1000000000; -- 1GB

-- Use streaming queries for large datasets
SELECT user_id, COUNT(*) as event_count
FROM events
WHERE timestamp >= '2024-01-01'
GROUP BY user_id
SETTINGS max_bytes_before_external_group_by = 1000000000

File system issues¶

Check and repair file system problems:

SELECT
    name,
    path,
    free_space,
    total_space
FROM system.disks

Data corruption¶

Handle corrupted data:

SELECT
    database,
    table,
    partition,
    name,
    rows,
    bytes_on_disk,
    marks_bytes,
    data_compressed_bytes
FROM system.parts
WHERE active = 1
  AND (rows = 0 OR bytes_on_disk = 0)

Network issues¶

Resolve network-related problems:

SELECT
    host,
    port,
    user,
    database
FROM system.clusters

Tinybird-specific notes¶

In Tinybird, STD_EXCEPTION errors often occur when:

• System resources are exhausted
• Data corruption in Data Sources
• Network issues between components
• Internal system failures
• Resource limits exceeded

To debug in Tinybird:

1. Check the Tinybird status page for system issues
2. Monitor resource usage in your workspace
3. Contact Tinybird support for persistent errors
4. Check if the issue affects other users

Best practices¶

Error prevention¶

• Monitor system resources regularly
• Implement proper error handling in applications
• Use appropriate query timeouts and limits
• Regular maintenance and monitoring

Troubleshooting¶

• Check system logs for patterns
• Verify recent system changes
• Test with simplified queries
• Monitor resource usage trends

System maintenance¶

• Regular table optimization
• Monitor disk space and memory usage
• Check for corrupted data
• Update ClickHouse versions when possible

Troubleshooting checklist¶

System resources¶

• [ ] Check available memory
• [ ] Verify disk space
• [ ] Monitor CPU usage
• [ ] Check network connectivity

Data integrity¶

• [ ] Verify table structure
• [ ] Check for corrupted parts
• [ ] Validate data formats
• [ ] Review recent data changes

Configuration¶

• [ ] Review system settings
• [ ] Check timeout configurations
• [ ] Verify resource limits
• [ ] Review security settings

Environment¶

• [ ] Check system logs
• [ ] Verify ClickHouse version
• [ ] Review recent deployments
• [ ] Check for system updates

Recovery strategies¶

Immediate actions¶

-- 1. Check system status
SELECT * FROM system.metrics WHERE metric LIKE '%error%'

-- 2. Verify table accessibility
SELECT COUNT(*) FROM system.tables LIMIT 1

-- 3. Check resource usage
SELECT * FROM system.processes

Long-term solutions¶

-- Set appropriate resource limits
SET max_memory_usage = 8000000000; -- 8GB
SET max_bytes_before_external_group_by = 1000000000; -- 1GB
SET max_bytes_before_external_sort = 1000000000; -- 1GB

-- Enable query logging for debugging
SET log_queries = 1

See also¶

• System Monitoring
• Performance Tuning
• Common system errors
• ClickHouse System Tables