FUNCTION_THROW_IF_VALUE_IS_NON_ZERO ClickHouse error¶

This error occurs when a function encounters a non-zero value and throws an exception as designed. It's common with validation functions, error checking, or conditional logic that intentionally throws errors.

The FUNCTION_THROW_IF_VALUE_IS_NON_ZERO error in ClickHouse (and Tinybird) happens when a function is designed to throw an exception when it encounters a non-zero value. This is intentional behavior for functions that perform validation, error checking, or conditional logic that requires throwing errors under specific conditions.

What causes this error¶

You'll typically see it when:

Using validation functions that check for error conditions
Calling functions designed to throw on non-zero values
Using error checking functions in conditional logic
Functions that validate data integrity
Error handling functions that propagate errors
Functions that check business logic conditions
Validation functions for data quality checks

This error is often intentional behavior. Check the function documentation to understand when and why it throws errors.

Example errors¶

Fails: validation function with non-zero value

SELECT throwIf(1, 'Value is non-zero')
-- Error: FUNCTION_THROW_IF_VALUE_IS_NON_ZERO: Value is non-zero

Fails: error checking function

SELECT throwIf(COUNT(*) > 0, 'Table has data')
FROM empty_table
-- Error: FUNCTION_THROW_IF_VALUE_IS_NON_ZERO: Table has data

Fails: business logic validation

SELECT throwIf(user_count > 1000, 'Too many users')
FROM (SELECT COUNT(*) as user_count FROM users)
-- Error: FUNCTION_THROW_IF_VALUE_IS_NON_ZERO: Too many users

Fails: data quality check

SELECT throwIf(invalid_count > 0, 'Data quality issue detected')
FROM (
    SELECT COUNT(*) as invalid_count
    FROM events
    WHERE user_id = 0 OR user_id IS NULL
)
-- Error: FUNCTION_THROW_IF_VALUE_IS_NON_ZERO: Data quality issue detected

How to fix it¶

Understand the function behavior¶

Check what triggers the error:

Check function behavior

-- Understand when throwIf throws errors
-- throwIf(condition, message) throws when condition is non-zero
SELECT
    CASE
        WHEN 0 THEN 'Zero - no error'
        WHEN 1 THEN 'One - will cause error'
        ELSE 'Other value'
    END as condition_value

Use conditional logic¶

Handle the condition before calling the function:

Fix: conditional handling

-- Instead of throwing error, handle condition
SELECT
    CASE
        WHEN COUNT(*) > 0 THEN 'Table has data'
        ELSE 'Table is empty'
    END as table_status
FROM empty_table

Use alternative functions¶

Replace throwing functions with non-throwing alternatives:

Fix: use non-throwing alternatives

-- Instead of throwIf, use if
SELECT if(COUNT(*) > 0, 'Table has data', 'Table is empty') as status
FROM empty_table

-- Or use CASE statement
SELECT
    CASE
        WHEN COUNT(*) > 0 THEN 'Table has data'
        ELSE 'Table is empty'
    END as status
FROM empty_table

Handle errors gracefully¶

Implement error handling in your application:

Fix: error handling

-- In your application, handle the error gracefully
-- Example pseudo-code:
--
-- try:
--     result = execute_query("SELECT throwIf(1, 'Error')")
-- except FunctionThrowIfValueIsNonZero as e:
--     # Handle the error condition
--     logger.warning(f"Validation failed: {e}")
--     # Take appropriate action

Common patterns and solutions¶

Data validation¶

Use validation functions appropriately:

Data validation approach

-- Validate data without throwing errors
SELECT
    COUNT(*) as total_rows,
    COUNT(CASE WHEN user_id = 0 OR user_id IS NULL THEN 1 END) as invalid_rows,
    if(invalid_rows > 0, 'Data quality issues found', 'Data quality OK') as status
FROM events
WHERE timestamp >= '2024-01-01'

Business logic checks¶

Implement business logic without throwing errors:

Business logic handling

-- Check business rules without throwing
SELECT
    user_id,
    COUNT(*) as event_count,
    CASE
        WHEN event_count > 1000 THEN 'High activity user'
        WHEN event_count > 100 THEN 'Active user'
        ELSE 'Regular user'
    END as user_category
FROM events
GROUP BY user_id

Error condition handling¶

Handle error conditions gracefully:

Error condition handling

-- Instead of throwing, return error status
SELECT
    CASE
        WHEN COUNT(*) = 0 THEN 'No data available'
        WHEN COUNT(*) > 10000 THEN 'Too much data'
        ELSE 'Data available'
    END as data_status,
    COUNT(*) as row_count
FROM events
WHERE timestamp >= '2024-01-01'

Conditional validation¶

Use conditional validation logic:

Conditional validation

-- Validate only when conditions are met
SELECT
    user_id,
    event_type,
    CASE
        WHEN user_id = 0 THEN 'Invalid user ID'
        WHEN event_type = '' THEN 'Empty event type'
        ELSE 'Valid record'
    END as validation_status
FROM events
WHERE timestamp >= '2024-01-01'

Tinybird-specific notes¶

In Tinybird, FUNCTION_THROW_IF_VALUE_IS_NON_ZERO errors often occur when:

Pipe transformations use validation functions
Materialized Views have error checking logic
API endpoints implement data validation
Data quality checks are implemented

To debug in Tinybird:

Review Pipe transformation logic for validation functions
Check Materialized View definitions for error conditions
Review API endpoint validation logic
Ensure data quality checks are appropriate

In Tinybird, use the Data Source preview to test validation logic before implementing it in Pipes.

Best practices¶

Function usage¶

Understand when functions throw errors
Use non-throwing alternatives when possible
Implement proper error handling
Document expected function behavior

Error handling¶

Handle errors gracefully in your application
Provide meaningful error messages
Implement fallback logic when possible
Log errors for debugging

Validation logic¶

Use appropriate validation functions
Implement business logic without throwing errors
Provide clear feedback on validation failures
Consider performance implications of validation

Configuration options¶

Error handling settings¶

Error handling configuration

-- Check error handling settings
SELECT
    name,
    value,
    description
FROM system.settings
WHERE name LIKE '%error%' OR name LIKE '%throw%'

Function behavior settings¶

Function behavior settings

-- Configure function behavior
SET function_throw_on_error = 0;  -- Disable throwing on errors
SET function_throw_on_zero = 0;   -- Disable throwing on zero values

Validation settings¶

Validation settings

-- Configure validation behavior
SET validate_data = 1;            -- Enable data validation
SET strict_validation = 0;        -- Disable strict validation

Alternative solutions¶

Use non-throwing functions¶

Replace throwing functions with alternatives:

Non-throwing alternatives

-- Instead of throwIf, use if
SELECT if(condition, 'true_value', 'false_value') as result

-- Instead of throwIf, use CASE
SELECT
    CASE
        WHEN condition THEN 'true_value'
        ELSE 'false_value'
    END as result

-- Instead of throwIf, use multiIf
SELECT multiIf(
    condition1, 'value1',
    condition2, 'value2',
    'default_value'
) as result

Implement custom validation¶

Create custom validation logic:

Custom validation

-- Create custom validation without throwing
SELECT
    user_id,
    event_type,
    timestamp,
    CASE
        WHEN user_id = 0 THEN 'INVALID_USER_ID'
        WHEN event_type = '' THEN 'INVALID_EVENT_TYPE'
        WHEN timestamp = '1970-01-01' THEN 'INVALID_TIMESTAMP'
        ELSE 'VALID'
    END as validation_status
FROM events
WHERE timestamp >= '2024-01-01'

Use error aggregation¶

Collect errors without throwing:

Error aggregation

-- Aggregate validation errors
SELECT
    'user_id' as field,
    COUNT(CASE WHEN user_id = 0 OR user_id IS NULL THEN 1 END) as error_count
FROM events
WHERE timestamp >= '2024-01-01'

UNION ALL

SELECT
    'event_type' as field,
    COUNT(CASE WHEN event_type = '' OR event_type IS NULL THEN 1 END) as error_count
FROM events
WHERE timestamp >= '2024-01-01'

Monitoring and prevention¶

Error tracking¶

Error monitoring

-- Track function throwing errors
-- Example pseudo-code:
--
-- def track_function_error(function_name, error_message, condition_value):
--     logger.error(f"Function {function_name} threw error: {error_message}")
--     logger.error(f"Condition value: {condition_value}")
--
--     # Track error metrics
--     increment_counter('function_throw_errors', {
--         'function': function_name,
--         'error_message': error_message,
--         'condition_value': condition_value
--     })

Validation monitoring¶

Validation monitoring

-- Monitor validation failures
SELECT
    validation_field,
    COUNT(*) as total_records,
    COUNT(CASE WHEN validation_status != 'VALID' THEN 1 END) as invalid_records,
    COUNT(CASE WHEN validation_status = 'VALID' THEN 1 END) as valid_records
FROM (
    SELECT
        user_id,
        CASE
            WHEN user_id = 0 OR user_id IS NULL THEN 'INVALID_USER_ID'
            ELSE 'VALID'
        END as validation_status,
        'user_id' as validation_field
    FROM events
    WHERE timestamp >= '2024-01-01'
)
GROUP BY validation_field

Performance monitoring¶

Performance monitoring

-- Monitor validation performance
SELECT
    validation_function,
    COUNT(*) as calls,
    AVG(execution_time) as avg_execution_time,
    MAX(execution_time) as max_execution_time
FROM validation_log
WHERE timestamp >= now() - INTERVAL 1 HOUR
GROUP BY validation_function