Method execute_distinct

graphlite/src/exec/executor.rs:6788–6819

Execute DISTINCT operation to remove duplicate rows

(&self, input_rows: Vec<Row>)

    /// Execute DISTINCT operation to remove duplicate rows
    fn execute_distinct(&self, input_rows: Vec<Row>) -> Result<Vec<Row>, ExecutionError> {
        use std::collections::HashSet;

        let mut seen_rows = HashSet::new();
        let mut unique_rows = Vec::new();

        for row in input_rows {
            // Create a unique key from all column values in the row
            let mut row_key = String::new();

            // Sort the keys to ensure consistent ordering for comparison
            let mut sorted_keys: Vec<_> = row.values.keys().collect();
            sorted_keys.sort();

            for key in sorted_keys {
                if let Some(value) = row.values.get(key) {
                    // Append key and value to create unique row signature
                    row_key.push_str(key);
                    row_key.push(':');
                    row_key.push_str(&format!("{:?}", value));
                    row_key.push('|');
                }
            }

            // Only include row if we haven't seen this exact combination before
            if seen_rows.insert(row_key) {
                unique_rows.push(row);
            }
        }

        Ok(unique_rows)
    }

    /// Execute a session statement - validates resources and returns session change request
    /// Following PostgreSQL/Oracle pattern: executor validates, pipeline handles session updates