cysqlite 0.3.5

cysqlite

cysqlite provides performant bindings to SQLite. cysqlite aims to be roughly compatible with the behavior of the standard lib sqlite3 module.

cysqlite supports standalone builds or dynamic-linking with the system SQLite.

Documentation

Overview

cysqlite is a Cython-based SQLite driver that provides:

• DB-API 2.0 compatible
• Performant query execution
• Transaction management with context-managers and decorators
• User-defined functions, aggregates, window functions, and virtual tables
• BLOB support
• Row objects with dict-like access
• Schema introspection utilities
• Asyncio support
• Easy to create fully self-contained builds

Performance

Installing

cysqlite can be installed as a pre-built binary wheel with SQLite embedded into the module:

pip install cysqlite

cysqlite can be installed from a source distribution (sdist) which will link against the system SQLite:

# Link against the system sqlite.
pip install --no-binary :all: cysqlite

If you wish to build cysqlite with encryption support, you can create a self-contained build that embeds SQLCipher. At the time of writing SQLCipher does not provide a source amalgamation, so cysqlite includes a script to build an amalgamation and place the sources into the root of your checkout:

# Obtain checkout of cysqlite.
git clone https://github.com/coleifer/cysqlite

# Automatically download latest source amalgamation.
cd cysqlite/
./scripts/fetch_sqlcipher  # Will add sqlite3.c and sqlite3.h in checkout.

# Build self-contained cysqlite with SQLCipher embedded.
SQLCIPHER=1 pip install .

Alternately, you can create a self-contained build that embeds SQLite3 Multiple Ciphers:

1. Obtain the latest *amalgamation.zip from the sqlite3mc releases page
2. Extract sqlite3mc_amalgamation.c and sqlite3mc_amalgamation.h into the root of the cysqlite checkout.
3. Run pip install .

Example

Example usage:

from cysqlite import connect

db = connect(':memory:')

db.execute('create table data (k, v)')

with db.atomic():
    db.executemany('insert into data (k, v) values (?, ?)',
                   [(f'k{i:02d}', f'v{i:02d}') for i in range(10)])
    print(db.last_insert_rowid())  # 10.

curs = db.execute('select * from data')
for row in curs:
    print(row)  # e.g., ('k00', 'v00')

# We can use named parameters with a dict as well.
row = db.execute_one('select * from data where k = :key and v = :val',
                     {'key': 'k05', 'val': 'v05'})
print(row)  # ('k05', 'v05')

db.close()

User-defined functions and hooks

cysqlite lets you extend SQLite with ordinary Python callables. Functions and collations are registered on the connection and automatically restored if it is closed and re-opened:

• Scalar functions: db.create_function(fn)
• Aggregates: db.create_aggregate(cls) (step() + finalize())
• Window functions: db.create_window_function(cls) (adds inverse() + value())
• Table-valued functions: @db.table_function(columns=[...]) over a generator
• Collations: db.create_collation(fn)

Connection hooks observe or veto activity (pass None to clear):

• Commit / rollback hooks: db.commit_hook(fn), db.rollback_hook(fn)
• Update hook: db.update_hook(fn) (fires on INSERT, UPDATE or DELETE)
• Authorizer: db.authorizer(fn)

# Scalar function.
db.create_function(str.title, 'title_case')
db.execute('select title_case(?)', ('heLLo wOrLd',)).fetchone()  # ('Hello World',)

# Table-valued function from a generator.
@db.table_function(columns=['value'])
def series(start, stop, step=1):
    i = start
    while i < stop:
        yield (i,)
        i += step

list(db.execute('select value from series(0, 10, 2)'))  # [(0,), (2,), (4,), (6,), (8,)]

# Veto a COMMIT from Python (a truthy return turns it into a ROLLBACK).
readonly = True
db.commit_hook(lambda: readonly)

See the user-defined functions guide for full examples.