psycopg2: insert multiple rows with one query

Question

I need to insert multiple rows with one query (number of rows is not constant), so I need to execute query like this one:

INSERT INTO t (a, b) VALUES (1, 2),         


        

Answer 1

Update with psycopg2 2.7:

The classic executemany() is about 60 times slower than @ant32 's implementation (called "folded") as explained in this thread: https://www.postgresql.org/message-id/20170130215151.GA7081%40deb76.aryehleib.com

This implementation was added to psycopg2 in version 2.7 and is called execute_values():

from psycopg2.extras import execute_values
execute_values(cur,
    "INSERT INTO test (id, v1, v2) VALUES %s",
    [(1, 2, 3), (4, 5, 6), (7, 8, 9)])

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Previous Answer:

To insert multiple rows, using the multirow VALUES syntax with execute() is about 10x faster than using psycopg2 executemany(). Indeed, executemany() just runs many individual INSERT statements.

@ant32 's code works perfectly in Python 2. But in Python 3, cursor.mogrify() returns bytes, cursor.execute() takes either bytes or strings, and ','.join() expects str instance.

So in Python 3 you may need to modify @ant32 's code, by adding .decode('utf-8'):

args_str = ','.join(cur.mogrify("(%s,%s,%s,%s,%s,%s,%s,%s,%s)", x).decode('utf-8') for x in tup)
cur.execute("INSERT INTO table VALUES " + args_str)

Or by using bytes (with b'' or b"") only:

args_bytes = b','.join(cur.mogrify("(%s,%s,%s,%s,%s,%s,%s,%s,%s)", x) for x in tup)
cur.execute(b"INSERT INTO table VALUES " + args_bytes)