Declarative, typed query language that compiles to SQL.
Project description
PreQL/Trilogy
pypreql is an experimental implementation of the PreQL/Trilogy (prequel trilogy) language, a modified SQL syntax that compiles to SQL intended to embrace the best features of SQL while fixing common pain points.
PreQL/Trilogy looks like SQL, but doesn't require table references, group by, or joins directly in queries, shifting some parts of a standard SQL query into a reusable, lightweight semantic binding layer. When you query, it puts the focus on what you want to get, not how you want to get it - you've already done that work once in your data model.
It's perfect for a modern data company that just can't quit SQL, but wants less pain, with a rich extension ecosystem to integrate with other tools like DBT.
PypreQL can be run locally to parse and execute preql [.preql] models.
The PreQL language spec itself will be linked from the above repo.
You can read more about the project here and try out an interactive demo on the page an interactive demo here.
PreQL looks like like SQL:
SELECT
name,
count(name) as name_count
WHERE
name='Elvis'
ORDER BY
name_count desc
LIMIT 10;
Goals
vs SQL, the goals are:
Preserve:
- Correctness
- Accessibility
Enhance:
- Simplicity
- Understandability
- Refactoring/mantainability
- Reusability
Maintain:
- Acceptable performance
Backends
The current PreQL implementation supports compiling to these SQL flavors:
- Bigquery
- SQL Server
- DuckDB
- Snowflake
Basic Example - Python
Preql can be run directly in python.
A bigquery example, similar to bigquery the quickstart
from preql import Dialects, Environment
environment = Environment()
environment.parse('''
key name string;
key gender string;
key state string;
key year int;
key yearly_name_count int; int;
datasource usa_names(
name:name,
number:yearly_name_count,
year:year,
gender:gender,
state:state
)
address bigquery-public-data.usa_names.usa_1910_2013;
'''
)
executor = Dialects.BIGQUERY.default_executor(environment=environment)
results = executor.execute_text(
'''SELECT
name,
sum(yearly_name_count) -> name_count
WHERE
name = 'Elvis'
ORDER BY
name_count desc
LIMIT 10;
'''
)
# multiple queries can result from one text batch
for row in results:
# get results for first query
answers = row.fetchall()
for x in answers:
print(x)
Basic Example - CLI
Preql can be run through a CLI tool, 'trilogy'.
After installing preql, you can run the trilogy CLI with two required positional arguments; the first the path to a file or a direct command, and second the dialect to run.
trilogy run <cmd or path to preql file> <dialect>
[!TIP] This will only work for basic backends, such as Bigquery with local default credentials; if the backend requires more configuration, the CLI will require additional config arguments.
The CLI can also be used for formatting. PreQL has a default formatting style that should always be adhered to.
trilogy fmt <path to preql file>
More Examples
Examples can be found in the public model repository. This is a good place to start for more complex examples.
Developing
Clone repository and install requirements.txt and requirements-test.txt.
Contributing
Please open an issue first to discuss what you would like to change, and then create a PR against that issue.
Similar in space
"Better SQL" has been a popular space. We believe Trilogy/PreQL takes a different approach then the following, but all are worth checking out. Please open PRs/comment for anything missed!
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