使用语义层优化 ClickHouse Assistant 对话

<background_information>
Context about your data and domain
</background_information>

<calculation_rules>
Specific formulas and business logic
</calculation_rules>

<tool_guidance>
How to use specific ClickHouse features
</tool_guidance>

<metric_calculations>
IMPORTANT: "active_sessions" is NOT a column. It must be calculated.

To calculate active sessions:
COUNT(DISTINCT session_id || '|' || user_id) AS active_sessions

This counts unique combinations of session and user identifiers.

When the user asks for "active sessions" or "session count", always use this formula:
SELECT
    date,
    COUNT(DISTINCT session_id || '|' || user_id) AS active_sessions
FROM events
GROUP BY date;

</metric_calculations>

<business_rules>
Revenue Calculation:
- Exclude refunded transactions: WHERE transaction_status != 'refunded'
- Apply regional tax rates using CASE expressions
- Use MRR for subscriptions:
  SUM(CASE
    WHEN billing_cycle = 'monthly' THEN amount
    WHEN billing_cycle = 'yearly' THEN amount / 12
    ELSE 0
  END) AS mrr

Traffic Source Classification:
Use CASE expression to categorize:
CASE
  WHEN traffic_source IN ('google', 'bing', 'organic') THEN 'Organic Search'
  WHEN traffic_source IN ('facebook', 'instagram', 'social') THEN 'Social Media'
  WHEN traffic_source = 'direct' THEN 'Direct'
  ELSE 'Other'
END AS source_category

Customer Segmentation:
- Enterprise: annual_contract_value >= 100000
- Mid-Market: annual_contract_value >= 10000 AND annual_contract_value < 100000
- SMB: annual_contract_value < 10000

Always include these categorizations when generating traffic or revenue reports.
</business_rules>

<data_structure_notes>
The user_status column uses numeric codes, not strings:
- 1 = 'active'
- 2 = 'inactive'
- 3 = 'suspended'
- 99 = 'deleted'

When filtering or displaying user status, always use:
CASE user_status
  WHEN 1 THEN 'active'
  WHEN 2 THEN 'inactive'
  WHEN 3 THEN 'suspended'
  WHEN 99 THEN 'deleted'
END AS status_label

The product_metadata column contains JSON strings that must be parsed:
SELECT
    product_id,
    JSONExtractString(product_metadata, 'category') AS category,
    JSONExtractInt(product_metadata, 'inventory_count') AS inventory
FROM products;
</data_structure_notes>

<terminology>
When users refer to "conversions", they mean:
- For e-commerce: transactions WHERE transaction_type = 'purchase'
- For SaaS: subscriptions WHERE subscription_status = 'active' AND first_payment_date IS NOT NULL

"Churn" is calculated as:
COUNT(DISTINCT user_id) WHERE last_active_date < today() - INTERVAL 90 DAY
AND previous_subscription_status = 'active'

"DAU" (Daily Active Users) means:
COUNT(DISTINCT user_id) WHERE activity_date = today()

"Qualified leads" must meet ALL criteria:
- lead_score >= 70
- company_size >= 50
- budget_confirmed = true
- contact_role IN ('Director', 'VP', 'C-Level')
</terminology>