Struct WindowRewriter 

pub struct WindowRewriter;

Rewrites window functions in SQL queries

Implementations

impl WindowRewriter

pub fn rewrite_statement(stmt: &mut Statement) -> Result<(), ParseError>

Rewrite a SQL statement to expand window functions.

Transforms window functions like TUMBLE into appropriate table functions and adds window_start/window_end columns.

Errors

Returns ParseError::WindowError if a window function cannot be rewritten.

Example

-- Input:
SELECT COUNT(*) FROM events
GROUP BY TUMBLE(event_time, INTERVAL '5' MINUTE)

-- Output:
SELECT window_start, window_end, COUNT(*)
FROM events
GROUP BY window_start, window_end

pub fn contains_window_function(expr: &Expr) -> bool

Check if expression contains a window function.

pub fn extract_window_function( expr: &Expr, ) -> Result<Option<WindowFunction>, ParseError>

Extract window function details from expression.

Parses the actual arguments from TUMBLE/HOP/SESSION function calls.

Supported syntax

• TUMBLE(time_column, interval) - 2 arguments
• HOP(time_column, slide_interval, window_size) - 3 arguments
• SLIDE(time_column, slide_interval, window_size) - alias for HOP
• SESSION(time_column, gap_interval) - 2 arguments

Errors

Returns ParseError::WindowError if:

• Function has empty name
• Wrong number of arguments for window type
• Arguments cannot be extracted

pub fn get_time_column_name(window: &WindowFunction) -> Option<String>

Extract the time column name from a window function.

Returns the column name as a string if extractable.

pub fn parse_interval_to_duration(expr: &Expr) -> Result<Duration, ParseError>

Parse an INTERVAL expression to Duration.

Supports: SECOND, MINUTE, HOUR, DAY

Errors

Returns ParseError::WindowError if the expression is not a valid interval.