sqlite-speed-test.py

import random
import sqlite3
import timeit
import numpy
import tempfile
import os.path


A_VALUES = ['foo', 'bar', 'baz']
B_VALUES = ['magrat', 'nanny', 'granny']


def make_db(path, make_index, rows=100000):
    conn = sqlite3.connect(path)
    conn.execute('''CREATE TABLE files (date integer, a text, b text)''')
    if make_index:
        conn.execute('''CREATE INDEX idx_date ON files (date DESC)''')
    conn.execute('''CREATE INDEX idx_a ON files (a)''')
    dates = list(range(rows))
    random.shuffle(dates)
    for date in dates:
        a = random.choice(A_VALUES)
        b = random.choice(B_VALUES)
        conn.execute('''INSERT INTO files VALUES (?, ?, ?)''', (date, a, b))
    conn.commit()
    conn.close()


def explain(conn, stmt):
    c = sqlite3.connect(conn)
    for row in c.execute('EXPLAIN QUERY PLAN ' + stmt):
        print('\t', row)
    c.close()


def test_once(conn, stmt, repeat=10, number=10):
    m = numpy.array(timeit.repeat('c = sqlite3.connect(conn); c.execute(stmt); c.close()',
                                  globals=dict(
                                      conn=conn, stmt=stmt, sqlite3=sqlite3),
                    repeat=repeat, number=number))
    m /= number
    return (numpy.mean(m), numpy.std(m) / numpy.sqrt(len(m)))


def test(conn_n, conn_i, stmt, **kwargs):
    print(stmt)
    print('\twithout index: {} +/- {}'.format(
        *test_once(conn_n, stmt, **kwargs)))
    explain(conn_n, stmt)
    print('\twith index   : {} +/- {}'.format(
        *test_once(conn_i, stmt, **kwargs)))
    explain(conn_i, stmt)
    print()


def main():
    with tempfile.TemporaryDirectory(prefix='sqlite-speed-test') as d:
        conn_n = os.path.join(d, 'n.db')
        make_db(conn_n, False)
        conn_i = os.path.join(d, 'i.db')
        make_db(conn_i, True)
        test(conn_n, conn_i, '''SELECT * FROM files ORDER BY date DESC LIMIT 10''')
        test(conn_n, conn_i, '''SELECT * FROM files WHERE date >= 99000 ORDER BY date DESC LIMIT 10''')
        test(conn_n, conn_i, '''SELECT * FROM files WHERE a = 'foo' ORDER BY date DESC LIMIT 10''')
        test(conn_n, conn_i, '''SELECT * FROM files WHERE date >= 99000 AND a = 'foo' ORDER BY date DESC LIMIT 10''')


if __name__ == '__main__':
    main()

SELECT * FROM files ORDER BY dateval DESC LIMIT 10
        without index: 0.6497548129999997 +/- 0.0011802204336985222
         (4, 0, 0, 'SCAN TABLE files')
         (18, 0, 0, 'USE TEMP B-TREE FOR ORDER BY')
        with index   : 0.0005200229999968543 +/- 7.557763301111602e-06
         (5, 0, 0, 'SCAN TABLE files USING INDEX IDX_date')

SELECT * FROM files WHERE dateval >= 99000 ORDER BY dateval DESC LIMIT 10
        without index: 0.4978252509999971 +/- 0.0005956959430678823
         (4, 0, 0, 'SCAN TABLE files')
         (20, 0, 0, 'USE TEMP B-TREE FOR ORDER BY')
        with index   : 0.0004957730000046468 +/- 4.144979865982506e-06
         (5, 0, 0, 'SEARCH TABLE files USING INDEX IDX_date (dateval>?)')

SELECT * FROM files WHERE randa = 'banana' ORDER BY dateval DESC LIMIT 10
        without index: 0.6311629120000021 +/- 0.0008121937958165911
         (5, 0, 0, 'SEARCH TABLE files USING INDEX IDX_randa (randa=?)')
         (22, 0, 0, 'USE TEMP B-TREE FOR ORDER BY')
        with index   : 0.6361734520000029 +/- 0.0007221630336897132
         (5, 0, 0, 'SEARCH TABLE files USING INDEX IDX_randa (randa=?)')
         (22, 0, 0, 'USE TEMP B-TREE FOR ORDER BY')

SELECT * FROM files WHERE dateval >= 99000 AND randa = 'banana' ORDER BY dateval DESC LIMIT 10
        without index: 0.6118271329999925 +/- 0.0011363213043028707
         (5, 0, 0, 'SEARCH TABLE files USING INDEX IDX_randa (randa=?)')
         (24, 0, 0, 'USE TEMP B-TREE FOR ORDER BY')
        with index   : 0.6189112849999969 +/- 0.0014941011420588394
         (5, 0, 0, 'SEARCH TABLE files USING INDEX IDX_randa (randa=?)')
         (24, 0, 0, 'USE TEMP B-TREE FOR ORDER BY')

The DBs I used were created using the following (adding/removing a date index as needed):

CREATE TABLE files (
dateval INTEGER,
randa TEXT,
randb TEXT,
randc TEXT
);
CREATE INDEX IDX_date ON files(dateval);

CREATE INDEX IDX_randa ON files(randa);

CREATE INDEX IDX_randb ON files(randb);

CREATE INDEX IDX_randc ON files(randc);

;WITH Rand1 AS (
SELECT 'apple' AS 'randa'
UNION
SELECT 'orange'
UNION
SELECT 'banana'
UNION
SELECT 'cucumber'
UNION
SELECT 'watermelon'
)
, rand2 AS (
SELECT 'ford' AS 'randb'
UNION
SELECT 'chevy'
UNION
SELECT 'jeep'
UNION
SELECT 'subaru'
UNION
SELECT 'mercedes'
)
,rand3 AS (
SELECT 'dog' AS 'randc'
UNION
SELECT 'cat'
UNION
SELECT 'squirrel'
UNION
SELECT 'frog'
UNION
SELECT 'shark'
)
, rand4 AS (
SELECT 1 AS 'n'
UNION ALL
SELECT n + 1
FROM
rand4
WHERE n+1 <= 50000
)

INSERT INTO files(randa, randb, randc, dateval)
SELECT
	*
FROM
	rand1 AS a
	CROSS JOIN rand2 AS b
	CROSS JOIN rand3 AS c
	CROSS JOIN rand4 AS d
ORDER By random()
;