Extra zero decimal digits after decoding NUMERIC (DECIMAL) type

[vemikhaylov]

• asyncpg version: 0.18.3
• PostgreSQL version: PostgreSQL 10.10 / PostgreSQL 11.5
• Do you use a PostgreSQL SaaS? If so, which? Can you reproduce
  the issue with a local PostgreSQL install?: Yes, problem is reproduced using the PostgreSQL provided by AWS and a local install
• Python version: 3.7
• Platform: Linux / Darwin 18.6.0 x86_64
• Do you use pgbouncer?: No
• Did you install asyncpg with pip?: Yes
• If you built asyncpg locally, which version of Cython did you use?: No
• Can the issue be reproduced under both asyncio and
  uvloop?: Yes

I have encountered that asyncpg decodes values of NUMERIC type with extra zero decimal digits despite the explicitly specified scale.

This code:

import asyncio
import asyncpg


async def main():
    conn = await asyncpg.connect()
    await conn.execute('''
        CREATE TABLE test_numeric(
            id serial PRIMARY KEY,
            value NUMERIC(1000, 8)
        )
    ''')
    await conn.execute('''
        INSERT INTO test_numeric(value) VALUES('0.00003000')
    ''')

    row = await conn.fetchrow('SELECT * FROM test_numeric;')
    print(row)
    await conn.close()

asyncio.get_event_loop().run_until_complete(main())

Produces the following output (12 digits right to the point while the scale of 8 was specified):

<Record id=1 value=Decimal('0.000030000000')>

However, in the database everything looks fine:

test=# SELECT * FROM test_numeric;
 id |   value    
----+------------
  1 | 0.00003000

[niranjan94]

Thanks @elprans for the speedy fix 😄