WITH FILL with interpolation

[filimonov]

SELECT *
FROM values('pos UInt16, val UInt16', (1, 10), (13, 130), (15, 150), (20, 200))
ORDER BY pos ASC WITH FILL

Query id: 78385df6-a0cf-49e1-bf3b-440ae0b4c626

┌─pos─┬─val─┐
│   1 │  10 │
│   2 │   0 │
│   3 │   0 │
│   4 │   0 │
│   5 │   0 │
│   6 │   0 │
│   7 │   0 │
│   8 │   0 │
│   9 │   0 │
│  10 │   0 │
│  11 │   0 │
│  12 │   0 │
│  13 │ 130 │
│  14 │   0 │
│  15 │ 150 │
│  16 │   0 │
│  17 │   0 │
│  18 │   0 │
│  19 │   0 │
│  20 │ 200 │
└─────┴─────┘

20 rows in set. Elapsed: 0.001 sec. 

I want interpolated numbers instead of zeros in val column.

[amosbird]

I also need similar features. Perhaps we can provide WITH FILL with a lambda function with arguments: begin_value, previous_value, next_value, end_value, index.

[rhuddleston]

previous_value would be very helpful

[alexey-milovidov]

It is easy to implement, but we need to figure out how to define the rules.
Especially if we want different rules for different columns, e.g. linear interpolation for numeric columns and filling with previous value for strings.

[den-crane]

implemented #35349 22.4