How to use currentUser() in ClickHouse

How do I get the current user in ClickHouse?

currentUser() returns the ClickHouse username executing the query.

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Description

What does currentUser() return?

currentUser() outputs the exact ClickHouse username that is running the statement. The value is pulled from the current session, making it ideal for auditing and security checks.

How do I call currentUser()?

Place currentUser() anywhere a scalar expression is allowed. Always include empty parentheses; the function takes no arguments.

SELECT currentUser() AS executing_user;

When should I use currentUser() in ecommerce databases?

Use it in INSERT … SELECT statements to log who loaded data, in WHERE clauses for row-level security, or in SELECT lists for real-time monitoring dashboards.

Auditing data loads

Capture the username whenever Orders or OrderItems are bulk-inserted to trace responsibility.

Row-level security

Filter Orders so analysts only see rows they own by comparing order_creator to currentUser().

Best practices for currentUser()

Combine currentUser() with initialUser() to distinguish proxied traffic. Store the value in a low-cardinality column when writing logs for efficient compression.

Which permissions are required?

No special privilege is needed; any authenticated user can call currentUser().

Can I reference currentUser() in Materialized Views?

Yes, but remember the function is evaluated at insert time, not at view query time. Ensure this matches your auditing intent.

Example: tag inserted orders with username

CREATE TABLE Orders_Audit AS SELECT *, currentUser() AS inserted_by, now() AS inserted_at FROM Orders;

The view above keeps a historical copy of every order plus who inserted it.

Why How to use currentUser() in ClickHouse is important

How to use currentUser() in ClickHouse Example Usage


-- Log daily revenue checks with the executing user
INSERT INTO RevenueAudit (audit_time, auditor, total_revenue)
SELECT  now(),
        currentUser(),
        sum(total_amount)
FROM Orders
WHERE order_date = today();

How to use currentUser() in ClickHouse Syntax


SELECT currentUser();
-- Returns username of the session

-- Practical ecommerce example
SELECT  o.id,
        o.total_amount,
        currentUser() AS seen_by
FROM Orders AS o
WHERE o.order_date = today();

Common Mistakes

Omitting parentheses: Writing CURRENT_USER instead of currentUser() raises a "Unknown identifier" error. Always add empty parentheses.
Confusing currentUser() with initialUser(): initialUser() shows the original login before SET ROLE or proxying. Use currentUser() for the effective permissions.