YDB Python DBAPI

Introduction

Python DBAPI to YDB, which provides both sync and async drivers and complies with PEP249.

Installation

pip install ydb-dbapi

Usage

To establish a new DBAPI connection you should provide host, port and database:

import ydb_dbapi

connection = ydb_dbapi.connect(
    host="localhost", port="2136", database="/local"
) # sync connection

async_connection = await ydb_dbapi.async_connect(
    host="localhost", port="2136", database="/local"
) # async connection

Usage of connection:

with connection.cursor() as cursor:
    cursor.execute("SELECT id, val FROM table")

    row = cursor.fetchone()
    rows = cursor.fetchmany(size=5)
    rows = cursor.fetchall()

Usage of async connection:

async with async_connection.cursor() as cursor:
    await cursor.execute("SELECT id, val FROM table")

    row = await cursor.fetchone()
    rows = await cursor.fetchmany(size=5)
    rows = await cursor.fetchall()

Query parameters

Standard mode (pyformat=True)

Pass pyformat=True to connect() to enable familiar Python DB-API parameter syntax such as %(name)s and %s. This mode is opt-in: the default connection mode (pyformat=False) uses YDB-style $name placeholders instead, so %(name)s and %s do not work unless pyformat=True is set explicitly. The driver will convert placeholders and infer YDB types from Python values automatically.

Named parameters — %(name)s with a dict:

connection = ydb_dbapi.connect(
    host="localhost", port="2136", database="/local",
    pyformat=True,
)

with connection.cursor() as cursor:
    cursor.execute(
        "SELECT * FROM users WHERE id = %(id)s AND active = %(active)s",
        {"id": 42, "active": True},
    )

Positional parameters — %s with a list or tuple:

with connection.cursor() as cursor:
    cursor.execute(
        "INSERT INTO users (id, name, score) VALUES (%s, %s, %s)",
        [1, "Alice", 9.8],
    )

Use %% to insert a literal % character in the query.

The driver validates pyformat placeholders before executing the query:

• do not mix named %(name)s and positional %s placeholders in one query;
• named placeholders require a dict with bare keys like {"id": 1};
• positional placeholders require a list or tuple;
• missing or extra parameters raise ProgrammingError;
• keys starting with $ are not allowed in pyformat=True mode.

Automatic type mapping:

Explicit types with ydb.TypedValue:

When automatic inference is not suitable (e.g. you need Int32 instead of Int64, or Json), wrap the value in ydb.TypedValue — it will be passed through unchanged:

import ydb

with connection.cursor() as cursor:
    cursor.execute(
        "INSERT INTO events (id, payload) VALUES (%(id)s, %(payload)s)",
        {
            "id": ydb.TypedValue(99, ydb.PrimitiveType.Int32),
            "payload": ydb.TypedValue('{"key": "value"}', ydb.PrimitiveType.Json),
        },
    )

If the driver cannot infer a YDB type for a Python value, it raises TypeError. Use ydb.TypedValue for such values or when you need an explicit YDB type.

Native YDB mode (default, deprecated)

Deprecated. Native YDB mode is the current default for backwards compatibility, but it will be removed in a future release. Migrate to pyformat=True at your earliest convenience.

By default (pyformat=False) the driver passes the query and parameters directly to the YDB SDK without any transformation. Use $name placeholders in the query and supply a dict with $-prefixed keys:

connection = ydb_dbapi.connect(
    host="localhost", port="2136", database="/local",
)

with connection.cursor() as cursor:
    cursor.execute(
        "SELECT * FROM users WHERE id = $id",
        {"$id": ydb.TypedValue(42, ydb.PrimitiveType.Int64)},
    )