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WindowImpl

risingwave_expr_impl::window_function::buffer

Trait WindowImpl 

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pub(super) trait WindowImpl {
    type Key: Ord;
    type Value: Clone;

    // Required methods
    fn preceding_saturated(
        &self,
        window: BufferRef<'_, Self::Key, Self::Value>,
    ) -> bool;
    fn following_saturated(
        &self,
        window: BufferRef<'_, Self::Key, Self::Value>,
    ) -> bool;
    fn recalculate_left_right(
        &mut self,
        window: BufferRefMut<'_, Self::Key, Self::Value>,
        hint: RecalculateHint,
    );
    fn shift_indices(&mut self, n: usize);

    // Provided methods
    fn closed_by_input(
        &self,
        window: BufferRef<'_, Self::Key, Self::Value>,
    ) -> bool { ... }
    fn watermark_bound(
        &self,
        _window: BufferRef<'_, Self::Key, Self::Value>,
    ) -> Option<WatermarkBound> { ... }
}
Expand description

A trait for sliding window implementations. This trait is used by WindowBuffer to determine the status of current window and how to slide the window.

Required Associated Types§

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type Key: Ord

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type Value: Clone

Required Methods§

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fn preceding_saturated( &self, window: BufferRef<'_, Self::Key, Self::Value>, ) -> bool

Whether the preceding half of the current window is saturated. By “saturated” we mean that every row that is possible to be in the preceding half of the current window is already in the buffer.

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fn following_saturated( &self, window: BufferRef<'_, Self::Key, Self::Value>, ) -> bool

Whether the following half of the current window is saturated.

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fn recalculate_left_right( &mut self, window: BufferRefMut<'_, Self::Key, Self::Value>, hint: RecalculateHint, )

Recalculate the left and right indices of the current window, according to the latest curr_idx and the hint.

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fn shift_indices(&mut self, n: usize)

Shift the indices stored by the WindowImpl by n positions. This should be called after evicting rows from the buffer.

Provided Methods§

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fn closed_by_input(&self, window: BufferRef<'_, Self::Key, Self::Value>) -> bool

Whether the current row exists and its window is closed by the rows in the buffer, given that no future row is less than the last one in the order of the order key.

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fn watermark_bound( &self, _window: BufferRef<'_, Self::Key, Self::Value>, ) -> Option<WatermarkBound>

The watermark of the order key that closes the current window, called only when the current row exists and its window is not closed by input. None means only future rows can close it, which is also the case for a non-ascending order, since a watermark only bounds future order values from below.

Dyn Compatibility§

This trait is dyn compatible.

In older versions of Rust, dyn compatibility was called "object safety".

Implementors§