Comments (1)
In the former case, the plan is:
0
┌─────────────────────────
│
│ ╭───────────────╮
0 │ │ FAST COUNT(*) │
│ ╰───────┬───────╯
│ │
│ │
│ │
│ ╭──────────┴──────────╮
│ │ DF [] │
1 │ │ PROJECT */0 COLUMNS │
│ ╰─────────────────────╯
In the latter, it is:
0 1
┌───────────────────────────────────────────────────────────────────────
│
│ ╭────────╮
0 │ │ SELECT │
│ ╰───┬┬───╯
│ ││
│ │╰─────────────────────────────────╮
│ │ │
│ │ ╭────────────────────────┴─────────────────────────╮
│ ╭──────┴──────╮ │ FROM: │
│ │ expression: │ │ SELECT [len()] FROM │
1 │ │ len() │ │ │
│ ╰─────────────╯ │ Parquet SCAN /tmp/tmppxstkd22/polars.parquet │
│ │ PROJECT */3 COLUMNS │
│ ╰──────────────────────────────────────────────────╯
In the latter case, column projection produces an IR scanning the parquet file projecting out all columns (the with_columns
option is the empty list). And then (presumably) len
of an empty table produces zero.
from polars.
Related Issues (20)
- cannot find function `as_struct` in this scope HOT 2
- QOL improvements for .rolling
- Include example with function accepting multiple arguments in `Expr.map_batches`
- Documentation issue in `normalize`/`name` parameter from `.value_counts()` method HOT 2
- writing to os.devnull
- `Series[list].explode()` should not return `None` for empty lists HOT 2
- write_database to snowflake with adbc engine spouts context canceled error log
- Cannot tell if hvplot version 0.10.0 >= 0.9.1 HOT 2
- dtype 'Time' gets converted to i64 when collect(streaming=True) is used. HOT 1
- `.agg_groups()` PanicException when not used in a group_by context
- Additional Parameter for json_normalize HOT 5
- fold shouldn't require that acc and exprs share the same dtype
- Adding `descending` parameter to `Expr.over` HOT 5
- polars.LazyFrame.head recommends using fetch()
- Reading large json file error: ComputeError: InputTooLarge at character 0
- Serialize for AnyType has a todo!() HOT 1
- File cache invalidation not triggered for HTTP if size is the same
- Loading parquet written from an Arrow table produces non-deterministic incorrect numbers since 1.2.0
- illegal hardware instruction with python 3.12.4 and polars 1.1.0 on MacOS Sanoma 14, M2 HOT 3
- Panic when call `hash()` on `struct` dtype HOT 1
Recommend Projects
-
React
A declarative, efficient, and flexible JavaScript library for building user interfaces.
-
Vue.js
🖖 Vue.js is a progressive, incrementally-adoptable JavaScript framework for building UI on the web.
-
Typescript
TypeScript is a superset of JavaScript that compiles to clean JavaScript output.
-
TensorFlow
An Open Source Machine Learning Framework for Everyone
-
Django
The Web framework for perfectionists with deadlines.
-
Laravel
A PHP framework for web artisans
-
D3
Bring data to life with SVG, Canvas and HTML. 📊📈🎉
-
Recommend Topics
-
javascript
JavaScript (JS) is a lightweight interpreted programming language with first-class functions.
-
web
Some thing interesting about web. New door for the world.
-
server
A server is a program made to process requests and deliver data to clients.
-
Machine learning
Machine learning is a way of modeling and interpreting data that allows a piece of software to respond intelligently.
-
Visualization
Some thing interesting about visualization, use data art
-
Game
Some thing interesting about game, make everyone happy.
Recommend Org
-
Facebook
We are working to build community through open source technology. NB: members must have two-factor auth.
-
Microsoft
Open source projects and samples from Microsoft.
-
Google
Google ❤️ Open Source for everyone.
-
Alibaba
Alibaba Open Source for everyone
-
D3
Data-Driven Documents codes.
-
Tencent
China tencent open source team.
from polars.