Orchestration
What is a UDF?
A UDF, a user-defined function, is your own logic the engine can call from a computed column or a query.
Updated
How it works
- You write a function.
- A column calls it.
- Results cache with the row.
What it is not
It is not a one-off script outside the table, and it is not a hosted function with no row cache.
UDF: this, and the thing it is confused with
| This | Not this | |
|---|---|---|
| Runs | Inside the column expression | Only in your notebook |
| Cache | With the row | Nowhere |
| Reuse | Any column or query | Copy-paste |
Where Pixeltable fits
Pixeltable registers Python UDFs and calls them from computed columns, so custom logic participates in incremental updates.
Questions
- How does UDF work?
- You write a function. A column calls it. Results cache with the row.
- What is UDF often confused with?
- It is not a one-off script outside the table, and it is not a hosted function with no row cache.