7ac3e97bfe
# Description Currently, the `into sqlite` command collects the entire input stream into a single Value, which soaks up the entire input into memory, before it ever tries to write anything to the DB. This is very problematic for large inputs; for example, I tried transforming a multi-gigabyte CSV file into SQLite, and before I knew what was happening, my system's memory was completely exhausted, and I had to hard reboot to recover. This PR fixes this problem by working directly with the pipeline stream, inserting into the DB as values are read from the stream. In order to facilitate working with the stream directly, I introduced a new `Table` struct to store the connection and a few configuration parameters, as well as to make it easier to lazily create the table on the first read value. In addition to the purely functional fixes, a few other changes were made to the serialization and user facing behavior. ### Serialization Much of the preexisting code was focused on generating the exact text needed for a SQL statement. This is unneeded and less safe than using the `rusqlite` crate's serialization for native Rust types along with prepared statements. ### User-Facing Changes Currently, the command is very liberal in the input types it accepts. The strategy is basically if it is a record, try to follow its structure and make an analogous SQL row, which is pretty reasonable. However, when it's not a record, it basically tries to guess what the user wanted and just makes a single column table and serializes the value into that one column, whatever type it may be. This has been changed so that it only accepts records as input. If the user wants to serialize non-record types into SQL, then they must explicitly opt into doing this by constructing a record or table with it first. For a utility for inserting data into SQL, I think it makes more sense to let the user choose how to convert their data, rather than make a choice for them that may surprise them. However, I understand this may be a controversial change. If the maintainers don't agree, I can change this back. #### Long switch names The `file_name` and `table_name` long form switches are currently snake_case and expect to be as such at the command line. These have been changed to kebab-case to be more conventional. # Tests + Formatting To test the memory consumption, I used [this publicly available index of all Wikipedia articles](https://dumps.wikimedia.org/enwiki/20230820/), using the first 10,000, 100,000, and 1,000,000 entries, in that order. I ran the following script to benchmark the changes against the current stable release: ```nu #!/usr/bin/nu # let shellbin = $"($env.HOME)/src/nushell/target/aarch64-linux-android/release/nu" let shellbin = "nu" const dbpath = 'enwiki-index.db' [10000, 100000, 1000000] | each {|rows| rm -f $dbpath; do { time -f '%M %e %U %S' $shellbin -c ( $"bzip2 -cdk ~/enwiki-20230820-pages-articles-multistream-index.txt.bz2 | head -n ($rows) | lines | parse '{offset}:{id}:{title}' | update cells -c [offset, id] { into int } | into sqlite ($dbpath)" ) } | complete | get stderr | str trim | parse '{rss_max} {real} {user} {kernel}' | update cells -c [rss_max] { $"($in)kb" | into filesize } | update cells -c [real, user, kernel] { $"($in)sec" | into duration } | insert rows $rows | roll right } | flatten | to nuon ``` This yields the following results Current stable release: |rows|rss_max|real|user|kernel| |-|-|-|-|-| |10000|53.6 MiB|770ms|460ms|420ms| |100000|209.6 MiB|6sec 940ms|3sec 740ms|4sec 380ms| |1000000|1.7 GiB|1min 8sec 810ms|38sec 690ms|42sec 550ms| This PR: |rows|rss_max|real|user|kernel| |-|-|-|-|-| |10000|38.2 MiB|780ms|440ms|410ms| |100000|39.8 MiB|6sec 450ms|3sec 530ms|4sec 160ms| |1000000|39.8 MiB|1min 3sec 230ms|37sec 440ms|40sec 180ms| # Note I started this branch kind of at the same time as my others, but I understand the feedback that smaller PRs are preferred. Let me know if it would be better to split this up. I do think the scope of the changes are on the bigger side even without the behavior changes I mentioned, so I'm not sure if that will help this particular PR very much, but I'm happy to oblige on request. |
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| .cargo | ||
| .githooks | ||
| .github | ||
| assets | ||
| benches | ||
| crates | ||
| devdocs | ||
| docker | ||
| scripts | ||
| src | ||
| tests | ||
| wix | ||
| .gitattributes | ||
| .gitignore | ||
| Cargo.lock | ||
| Cargo.toml | ||
| CODE_OF_CONDUCT.md | ||
| CONTRIBUTING.md | ||
| Cross.toml | ||
| LICENSE | ||
| README.md | ||
| rust-toolchain.toml | ||
| toolkit.nu | ||
Nushell
A new type of shell.
Table of Contents
- Status
- Learning About Nu
- Installation
- Configuration
- Philosophy
- Goals
- Officially Supported By
- Contributing
- License
Status
This project has reached a minimum-viable-product level of quality. Many people use it as their daily driver, but it may be unstable for some commands. Nu's design is subject to change as it matures.
Learning About Nu
The Nushell book is the primary source of Nushell documentation. You can find a full list of Nu commands in the book, and we have many examples of using Nu in our cookbook.
We're also active on Discord and Twitter; come and chat with us!
Installation
To quickly install Nu:
# Linux and macOS
brew install nushell
# Windows
winget install nushell
To use Nu in GitHub Action, check setup-nu for more detail.
Detailed installation instructions can be found in the installation chapter of the book. Nu is available via many package managers:
For details about which platforms the Nushell team actively supports, see our platform support policy.
Configuration
The default configurations can be found at sample_config which are the configuration files one gets when they startup Nushell for the first time.
It sets all of the default configuration to run Nushell. From here one can then customize this file for their specific needs.
To see where config.nu is located on your system simply type this command.
$nu.config-path
Please see our book for all of the Nushell documentation.
Philosophy
Nu draws inspiration from projects like PowerShell, functional programming languages, and modern CLI tools. Rather than thinking of files and data as raw streams of text, Nu looks at each input as something with structure. For example, when you list the contents of a directory what you get back is a table of rows, where each row represents an item in that directory. These values can be piped through a series of steps, in a series of commands called a 'pipeline'.
Pipelines
In Unix, it's common to pipe between commands to split up a sophisticated command over multiple steps. Nu takes this a step further and builds heavily on the idea of pipelines. As in the Unix philosophy, Nu allows commands to output to stdout and read from stdin. Additionally, commands can output structured data (you can think of this as a third kind of stream). Commands that work in the pipeline fit into one of three categories:
- Commands that produce a stream (e.g.,
ls) - Commands that filter a stream (e.g.,
where type == "dir") - Commands that consume the output of the pipeline (e.g.,
table)
Commands are separated by the pipe symbol (|) to denote a pipeline flowing left to right.
> ls | where type == "dir" | table
╭────┬──────────┬──────┬─────────┬───────────────╮
│ # │ name │ type │ size │ modified │
├────┼──────────┼──────┼─────────┼───────────────┤
│ 0 │ .cargo │ dir │ 0 B │ 9 minutes ago │
│ 1 │ assets │ dir │ 0 B │ 2 weeks ago │
│ 2 │ crates │ dir │ 4.0 KiB │ 2 weeks ago │
│ 3 │ docker │ dir │ 0 B │ 2 weeks ago │
│ 4 │ docs │ dir │ 0 B │ 2 weeks ago │
│ 5 │ images │ dir │ 0 B │ 2 weeks ago │
│ 6 │ pkg_mgrs │ dir │ 0 B │ 2 weeks ago │
│ 7 │ samples │ dir │ 0 B │ 2 weeks ago │
│ 8 │ src │ dir │ 4.0 KiB │ 2 weeks ago │
│ 9 │ target │ dir │ 0 B │ a day ago │
│ 10 │ tests │ dir │ 4.0 KiB │ 2 weeks ago │
│ 11 │ wix │ dir │ 0 B │ 2 weeks ago │
╰────┴──────────┴──────┴─────────┴───────────────╯
Because most of the time you'll want to see the output of a pipeline, table is assumed.
We could have also written the above:
> ls | where type == "dir"
Being able to use the same commands and compose them differently is an important philosophy in Nu.
For example, we could use the built-in ps command to get a list of the running processes, using the same where as above.
> ps | where cpu > 0
╭───┬───────┬───────────┬───────┬───────────┬───────────╮
│ # │ pid │ name │ cpu │ mem │ virtual │
├───┼───────┼───────────┼───────┼───────────┼───────────┤
│ 0 │ 2240 │ Slack.exe │ 16.40 │ 178.3 MiB │ 232.6 MiB │
│ 1 │ 16948 │ Slack.exe │ 16.32 │ 205.0 MiB │ 197.9 MiB │
│ 2 │ 17700 │ nu.exe │ 3.77 │ 26.1 MiB │ 8.8 MiB │
╰───┴───────┴───────────┴───────┴───────────┴───────────╯
Opening files
Nu can load file and URL contents as raw text or structured data (if it recognizes the format). For example, you can load a .toml file as structured data and explore it:
> open Cargo.toml
╭──────────────────┬────────────────────╮
│ bin │ [table 1 row] │
│ dependencies │ {record 25 fields} │
│ dev-dependencies │ {record 8 fields} │
│ features │ {record 10 fields} │
│ package │ {record 13 fields} │
│ patch │ {record 1 field} │
│ profile │ {record 3 fields} │
│ target │ {record 3 fields} │
│ workspace │ {record 1 field} │
╰──────────────────┴────────────────────╯
We can pipe this into a command that gets the contents of one of the columns:
> open Cargo.toml | get package
╭───────────────┬────────────────────────────────────╮
│ authors │ [list 1 item] │
│ default-run │ nu │
│ description │ A new type of shell │
│ documentation │ https://www.nushell.sh/book/ │
│ edition │ 2018 │
│ exclude │ [list 1 item] │
│ homepage │ https://www.nushell.sh │
│ license │ MIT │
│ metadata │ {record 1 field} │
│ name │ nu │
│ repository │ https://github.com/nushell/nushell │
│ rust-version │ 1.60 │
│ version │ 0.72.0 │
╰───────────────┴────────────────────────────────────╯
And if needed we can drill down further:
> open Cargo.toml | get package.version
0.72.0
Plugins
Nu supports plugins that offer additional functionality to the shell and follow the same structured data model that built-in commands use. There are a few examples in the crates/nu_plugins_* directories.
Plugins are binaries that are available in your path and follow a nu_plugin_* naming convention.
These binaries interact with nu via a simple JSON-RPC protocol where the command identifies itself and passes along its configuration, making it available for use.
If the plugin is a filter, data streams to it one element at a time, and it can stream data back in return via stdin/stdout.
If the plugin is a sink, it is given the full vector of final data and is given free reign over stdin/stdout to use as it pleases.
The awesome-nu repo lists a variety of nu-plugins while the showcase repo shows off informative blog posts that have been written about Nushell along with videos that highlight technical topics that have been presented.
Goals
Nu adheres closely to a set of goals that make up its design philosophy. As features are added, they are checked against these goals.
-
First and foremost, Nu is cross-platform. Commands and techniques should work across platforms and Nu has first-class support for Windows, macOS, and Linux.
-
Nu ensures compatibility with existing platform-specific executables.
-
Nu's workflow and tools should have the usability expected of modern software in 2022 (and beyond).
-
Nu views data as either structured or unstructured. It is a structured shell like PowerShell.
-
Finally, Nu views data functionally. Rather than using mutation, pipelines act as a means to load, change, and save data without mutable state.
Officially Supported By
Please submit an issue or PR to be added to this list.
Contributing
See Contributing for details. Thanks to all the people who already contributed!
License
The project is made available under the MIT license. See the LICENSE file for more information.