ClickHouse

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Overview

• Self-hosted ClickHouse
• ClickHouse Cloud
• Altinity Cloud

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Connection Details

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Setting Up a Read-Only User

-- Create user
CREATE USER plumi_readonly IDENTIFIED BY 'your_secure_password';

-- Grant read access
GRANT SELECT ON analytics.* TO plumi_readonly;

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ClickHouse Cloud

1. Go to your ClickHouse Cloud console
2. Navigate to Settings > Security
3. Add Plumi’s IP to the allowed list
4. Use the provided hostname and credentials

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Best Practices

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Query Optimization

• Use aggregations (GROUP BY, SUM, COUNT)
• Filter by partitioning columns first
• Avoid SELECT * on large tables
• Use LIMIT when exploring data

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Example Queries

-- Efficient: Uses aggregation and filtering
SELECT
  toDate(timestamp) as date,
  count() as events
FROM events
WHERE timestamp >= today() - 30
GROUP BY date
ORDER BY date;

-- Efficient: Uses sampling for exploration
SELECT *
FROM large_table
SAMPLE 0.01  -- 1% sample
LIMIT 1000;

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Troubleshooting

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Connection Timeout

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Memory Limit Exceeded