The Fill function for interpolation is really nice, but there's so many different ways to perform interpolation I'd like a lot more detail on what methods are available and which is used by default.
The Fill function for interpolation is really nice, but there's so many different ways to perform interpolation I'd like a lot more detail on what methods are available and which is used by default.
Indeed. Previously, when computing latency histograms from sampled events, I've abused DuckDB SQL cross join/cartesian products to generate zero values for "empty buckets" within a single SQL statement [1]. But makes the SQL unnecessarily complex & slower too, so I quickly moved that empty bucket rendering functionality to the frontend...
[1]: Example DuckDB SQL with generated bucket lists and cross join + outer join: https://github.com/tanelpoder/0xtools/blob/master/tools/sql/...
Feature author here. The new FILL uses linear interpolation (and extrapolation at the ends). There were a bunch of other algorithms requested (e.g., cubic splines), but the syntax was not clear.
I think the real solution is to add support for non-aggregate window functions in the catalogue. Right now, they are all hard-coded, but if they were extensible, there are a number applications in addition to filling that could be supported.
You can always manually define your interpolation:
is kind of the same as fill.From there you can go crazy and define whatever insane interpolations you want.
One limitation is that you can't distinguish the data boundaries from missing values (nulls at the edges vs. nulls in the bulk).
I guess another limitation is if you have multiple nulls after each other...