README.md

sqlalchemy_window

A SQLAlchemy plugin to add support for PostgreSQL WINDOW clause.

NOTE: only supports SQLAlchemy 2.0 and higher.

Example

Newer versions (>= 0.1.3) allow you to use Window.over_self interface for window functions:

import sqlalchemy as sa
from sqlalchemy_window import select, window

metadata = sa.MetaData()
table = sa.Table(
  "prices",
  metadata,
  sa.Column("asset", sa.String(16), primary_key=True),
  sa.Column("ts", sa.DateTime(timezone=True), primary_key=True),
  sa.Column("price", sa.Numeric, nullable=False),
)

w = window("w", partition_by=table.c["asset"], order_by=table.c["ts"], range_=(None, None))

query = select(
  w.over_self(sa.func.first_value(table.c["price"])).label("open"),
  w.over_self(sa.func.max(table.c["price"])).label("high"),
  w.over_self(sa.func.min(table.c["price"])).label("low"),
  w.over_self(sa.func.last_value(table.c["price"])).label("close"),
).where(sa.func.cast(table.c["ts"], sa.Date) == '2023-01-01').window(w)

Before that, to build above query you would use over_window factory:

query = select(
  over_window(sa.func.first_value(table.c["price"]), w).label("open"),
  over_window(sa.func.max(table.c["price"]), w).label("high"),
  over_window(sa.func.min(table.c["price"]), w).label("low"),
  over_window(sa.func.last_value(table.c["price"]), w).label("close"),
).where(sa.func.cast(table.c["ts"], sa.Date) == '2023-01-01').window(w)

You can still use over_window in newer versions.

Development

To setup a development environment run:

python3 -m venv venv
source ./venv/bin/activate
pip install --upgrade pip
pip install -r dev-requirements.txt -e .
pre-commit install

Running tests:

make test
make coverage

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A waterfountain1996 project.