https://github.com/rpolars/r-polarssql

A Polars backend for R DBI and dbplyr
https://github.com/rpolars/r-polarssql

dplyr dplyr-sql-backends polars r

Last synced: 3 months ago
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A Polars backend for R DBI and dbplyr

• Host: GitHub
• URL: https://github.com/rpolars/r-polarssql
• Owner: rpolars
• License: other
• Created: 2023-11-09T15:50:07.000Z (12 months ago)
• Default Branch: main
• Last Pushed: 2024-05-25T15:39:45.000Z (6 months ago)
• Last Synced: 2024-06-30T09:16:10.100Z (4 months ago)
• Topics: dplyr, dplyr-sql-backends, polars, r
• Language: R
• Homepage: https://rpolars.github.io/r-polarssql/
• Size: 3.92 MB
• Stars: 21
• Watchers: 4
• Forks: 0
• Open Issues: 3
• Metadata Files:
  • Readme: README.Rmd
  • License: LICENSE

Awesome Lists containing this project

• awesome-polars - polarssql - `polarssql` experimental package which is a DBI-compliant interface to Polars. (Libraries/Packages/Scripts / R)

README

        
---

output:

  github_document:

    html_preview: false

---

```{r}

#| include: false

knitr::opts_chunk$set(

  collapse = TRUE,

  comment = "#>",

  fig.path = "man/figures/README-",

  out.width = "100%"

)

```

# polarssql

[![polarssql status badge](https://rpolars.r-universe.dev/badges/polarssql)](https://rpolars.r-universe.dev)

[![CRAN status](https://www.r-pkg.org/badges/version/polarssql)](https://CRAN.R-project.org/package=polarssql)

`{polarssql}` is an experimental DBI-compliant interface to [Polars](https://www.pola.rs/).

Polars is not an actual database, so does not support full `{DBI}` functionality.

Please check [the Polars User Guide](https://pola-rs.github.io/polars/user-guide/sql/intro/)

for supported SQL features.

## Installation

The [`polars`](https://rpolars.github.io/) R package and `{polarssql}`

can be installed from [R-universe](https://rpolars.r-universe.dev/):

```r

Sys.setenv(NOT_CRAN = "true") # for installing the polars package with pre-built binary

install.packages("polarssql", repos = c("https://rpolars.r-universe.dev", getOption("repos")))

```

## Example

```{r}

library(DBI)

con <- dbConnect(polarssql::polarssql())

dbWriteTable(con, "mtcars", mtcars)

# We can fetch all results:

res <- dbSendQuery(con, "SELECT * FROM mtcars WHERE cyl = 4")

dbFetch(res)

# Clear the result

dbClearResult(res)

# Or a chunk at a time

res <- dbSendQuery(con, "SELECT * FROM mtcars WHERE cyl = 4")

while (!dbHasCompleted(res)) {

  chunk <- dbFetch(res, n = 5)

  print(nrow(chunk))

}

# Clear the result

dbClearResult(res)

# We can use table functions to read files directly:

tf <- tempfile(fileext = ".parquet")

on.exit(unlink(tf))

polars::as_polars_lf(mtcars)$sink_parquet(tf)

dbGetQuery(con, paste0("SELECT * FROM read_parquet('", tf, "') ORDER BY mpg DESC LIMIT 3"))

```

`{polarssql}` also provides functions that are simpler to use, inspired by the `{duckdb}` package,

```{r}

library(polarssql)

# These functions use the built-in connection by default, so we don't need to specify connection

# Resgister a data.frame to the built-in connection

polarssql_register(df = mtcars)

# Get the query result as a polars LazyFrame

polarssql_query("SELECT * FROM df WHERE cyl = 4")

# Unregister the table

polarssql_unregister("df")

```

And, basic supports for `{dbplyr}` is also implemented.

```{r}

library(dplyr, warn.conflicts = FALSE)

# Resgister a data.frame to the built-in connection, and query it via dbplyr

tbl_polarssql(mtcars) |>

  filter(cyl == 4) |>

  arrange(desc(mpg)) |>

  head(3) |>

  compute()

```