StreamSQL Expression Functions

Expression functions are used for dynamic expression calculation.

EXPRESSION - Expression Function

Syntax: expression(expr_str)
Description: Dynamically calculates an expression string.
Incremental Calculation: Not Supported
Example:

SELECT expression('price * quantity') as total FROM orders

EXPR - Expression Function (Abbreviation)

Syntax: expr(expr_str)
Description: Dynamically calculates an expression string (abbreviated form of EXPRESSION).
Incremental Calculation: Not Supported
Example:

SELECT expr('temperature > 30') as is_hot FROM sensors

Incremental Calculation Explanation

Performance Advantages

Functions that support incremental calculation have significant performance advantages in stream processing:

• Memory Efficiency: No need to save historical data
• Calculation Efficiency: Avoids repeated calculations
• Real-time: Results are updated in real-time

Custom Function Extension

To extend more functions, please refer to:

• Custom Function Development Guide
• Plugin Development Documentation

📚 Related Documentation

• Multi-row Functions - Learn detailed usage of multi-row functions
• Aggregate Functions - Learn detailed usage of aggregate functions
• SQL Reference - View complete SQL syntax reference