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https://github.com/asg017/sqlite-lines
A SQLite extension for reading large files line-by-line (NDJSON, logs, txt, etc.)
https://github.com/asg017/sqlite-lines
sqlite sqlite-extension
Last synced: 5 days ago
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A SQLite extension for reading large files line-by-line (NDJSON, logs, txt, etc.)
- Host: GitHub
- URL: https://github.com/asg017/sqlite-lines
- Owner: asg017
- License: mit
- Created: 2022-04-25T19:11:46.000Z (over 2 years ago)
- Default Branch: main
- Last Pushed: 2023-10-07T06:04:44.000Z (about 1 year ago)
- Last Synced: 2024-10-25T09:31:03.429Z (11 days ago)
- Topics: sqlite, sqlite-extension
- Language: C
- Homepage:
- Size: 3.2 MB
- Stars: 392
- Watchers: 4
- Forks: 9
- Open Issues: 10
-
Metadata Files:
- Readme: README.md
- License: LICENSE
Awesome Lists containing this project
- awesome-sqlite - github.com/asg017/sqlite-lines - SQLite extension for reading large files line-by-line (NDJSON, logs, txt, etc.) (Extensions)
README
# sqlite-lines
`sqlite-lines` is a SQLite extension for reading lines from a file or blob.
See [Benchmarks](./benchmarks) for more info.
## Usage
```sql
.load ./lines0
select line from lines_read('logs.txt');
```
`sqlite-lines` is great for line-oriented datasets, like [ndjson](https://ndjson.org/) or [JSON Lines](https://jsonlines.org/), when paired with SQLite's [JSON support](https://www.sqlite.org/json1.html). Here, we calculate the top 5 country participants in Google's [Quick, Draw!](https://quickdraw.withgoogle.com/data) dataset for [`calendars.ndjson`](https://storage.googleapis.com/quickdraw_dataset/full/simplified/calendar.ndjson):
```sql
select
line ->> '$.countrycode' as countrycode,
count(*)
from lines_read('./calendar.ndjson')
group by 1
order by 2 desc
limit 5;
/*
┌─────────────┬──────────┐
│ countrycode │ count(*) │
├─────────────┼──────────┤
│ US │ 141001 │
│ GB │ 22560 │
│ CA │ 11759 │
│ RU │ 9250 │
│ DE │ 8748 │
└─────────────┴──────────┘
*/
```
Use the SQLite CLI's [`fsdir()`](https://sqlite.org/cli.html#file_i_o_functions) table functions with `lines_read()` to read lines from every file in a directory.
```sql
select
name as file,
lines.rowid as line_number,
line
from fsdir('logs')
join lines_read(name) as lines
where name like '%.txt';
/*
┌─────────────────────┬──────┐
│ file │ line_number | line │
├───────┼─────────────┤──────┤
| a.txt | 1 | x |
| a.txt | 2 | y |
| a.txt | 3 | z |
| b.txt | 1 | xx |
| b.txt | 2 | yy |
| c.txt | 1 | xxx |
└───────┴─────────────┴──────┘
*/
```
## Documentation
See [`docs.md`](./docs.md) for a full API Reference and detailed documentation.
## Installing
| Language | Install | |
| -------------- | ---------------------------------------------------------- | ----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- |
| Python | `pip install sqlite-lines` | [](https://pypi.org/project/sqlite-lines/) |
| Datasette | `datasette install datasette-sqlite-lines` | [](https://datasette.io/plugins/datasette-sqlite-lines) |
| Node.js | `npm install sqlite-lines` | [](https://www.npmjs.com/package/sqlite-lines) |
| Deno | [`deno.land/x/sqlite_lines`](https://deno.land/x/sqlite_lines) | [](https://deno.land/x/sqlite_lines) |
| Ruby | `gem install sqlite-lines` |  |
| Github Release | |  |
The [Releases page](https://github.com/asg017/sqlite-lines/releases) contains pre-built binaries for Linux amd64 and MacOS (amd64, no arm).
### As a loadable extension
If you want to use `sqlite-lines` as a [Runtime-loadable extension](https://www.sqlite.org/loadext.html), Download the `lines0.dylib` (for MacOS) or `lines0.so` file from a release and load it into your SQLite environment.
> **Note:**
> The `0` in the filename (`lines0.dylib` or `lines0.so`) denotes the major version of `sqlite-lines`. Currently `sqlite-lines` is pre v1, so expect breaking changes in future versions.
For example, if you are using the [SQLite CLI](https://www.sqlite.org/cli.html), you can load the library like so:
```sql
.load ./lines0
select lines_version();
-- v0.0.1
```
Or in Python, using the builtin [sqlite3 module](https://docs.python.org/3/library/sqlite3.html):
```python
import sqlite3
con = sqlite3.connect(":memory:")
con.enable_load_extension(True)
con.load_extension("./lines0")
print(con.execute("select lines_version()").fetchone())
# ('v0.0.1',)
```
Or in Node.js using [better-sqlite3](https://github.com/WiseLibs/better-sqlite3):
```javascript
const Database = require("better-sqlite3");
const db = new Database(":memory:");
db.loadExtension("./lines0");
console.log(db.prepare("select lines_version()").get());
// { 'lines_version()': 'v0.0.1' }
```
Or with [Datasette](https://datasette.io/) (using the "no filesystem" version to limit security vulnerabilities):
```
datasette data.db --load-extension ./lines_nofs0
```
Windows is not supported - [yet](https://github.com/asg017/sqlite-lines/issues/4)!
### From the browser with WASM/JavaScript
`sqlite-lines` is also distributed as a standalone [SQL.js](https://github.com/sql-js/sql.js) library. It's essentially a fork of the original SQL.js library, with the addition of `sqlite-lines` functions like `lines_version()` and `lines()`.
Check out [this Observable notebook](https://observablehq.com/@asg017/introducing-sqlite-lines) for the full demonstration. The [Releases page](https://github.com/asg017/sqlite-lines/releases) contains the JavaScript and WASM files.
### The sqlite-lines CLI
`sqlite-lines` comes with an example CLI modeled after [ndjson-cli](https://github.com/mbostock/ndjson-cli) that demos the speed and versatility of `sqlite-lines`. Download a pre-compiled version from the [Releases page](https://github.com/asg017/sqlite-lines/releases), or build yourself with:
```
make cli
./dist/sqlite-lines
```
The `sqlite-lines` CLI reads data from stdin and applies transformations with SQL code through its arguments.
The first argument should be a SQL expression that is used transform a single line from stdlin. The available columns are `rowid`, which is the "line number" that is being processed, and `d`, an alias for `line`, which is the text content of the current line (inspired by ndjson-cli). For example, to uppercase every line from a file with [`upper()`](https://www.sqlite.org/lang_corefunc.html#upper):
```bash
$ cat names.txt | sqlite-lines 'rowid || upper(d)'
1ALEX
2BRIAN
3CRAIG
```
This includes SQLite's new JSON `->` and `->>` operators for NDJSON/JSONL files:
```bash
$ cat data.ndjson | sqlite-lines 'd ->> "$.id"'
$ cat data.ndjson | sqlite-lines 'json_object("name", d ->> "$.name", "age": d ->> "$.stats.age")'
```
The second argument is another SQL expression that's used in the WHERE statement of the underlying SQL query to filter out lines.
```bash
# get the names of all people older than 40
cat data.ndjson | sqlite-lines 'd ->> "$.name"' 'd ->> "$.age" > 40'
```
The third argument is another SQL expression that's used in the GROUP BY statement of the underlying SQL query to aggregate lines.
### A Note on CSV Parsing
`sqlite-lines` isn't a great option for CSVs. Technically you can, but the moment your data has a `\n` character in a field or header, then you'll get corrupted results.
Instead, you should use the "official" [CSV Virtual Table](https://www.sqlite.org/csv.html), or use the [`.import`](https://www.sqlite.org/cli.html#csv) command in the SQLite CLI.