Sample the first row from a window pane

[laysakura]

Is your feature request related to a problem? Please describe.

Describe the solution you'd like

Use DISTINCT ON operator with ORDER BY clause.

https://stackoverflow.com/questions/3800551/select-first-row-in-each-group-by-group/7630564#7630564

Describe alternatives you've considered

• WITH clause
• sub query

https://stackoverflow.com/questions/3800551/select-first-row-in-each-group-by-group/3800572#3800572

Additional context

Want "initial row from 100ms window" (100ms sampling).

Current sampling example is not good in that it can only take aggregated column values.

https://github.com/SpringQL/SpringQL/blob/main/springql-core/tests/e2e_sampling.rs#L86-L87