feat: support limit and offset clause

[wangrunji0408]

In this PR, we introduce slice operation for array and data chunk. Current implementation is simply copying the data, which is very inefficient. I plan to turn the DataChunk into a reference to array slice (like Bytes) in future PR. Any better ideas for this problem?

[skyzh]

We may use logical_rows or visibility bitmap :)

[wangrunji0408]

What is logical_rows? A reference to array + index array?

[skyzh]

Yes. logical_rows: &[usize] is an index into array. e.g. logical_rows = [2, 1, 0] yields a reverse order of array. From my experience, it's better to define it as a enum, LogicalRows::Sequential and LogicalRows::Indexed(&[usize]), or Option<&[usize]>.

Another approach is to use visibility. Then we might go back to RisingWave and our previous versions.

[skyzh]

Good work!

[TennyZhuang]

Yes. logical_rows: &[usize] is an index into array. e.g. logical_rows = [2, 1, 0] yields a reverse order of array. From my experience, it's better to define it as a enum, LogicalRows::Sequential and LogicalRows::Indexed(&[usize]), or Option<&[usize]>.

Another approach is to use visibility. Then we might go back to RisingWave and our previous versions.

We can do this later, with full benchmark.