Migrate from asyncpg to psycopg v3

[aasseman]

psycopg v3 supports async, while psycopg2 did not: https://www.psycopg.org/psycopg3/docs/advanced/async.html

Also, it will solve the issue in #84 (comment). I tried on a little snippet to make sure, and it works well:

async def test_psycopg3(self, postgresql):
    conn_string =   f"host={postgresql.info.host} " \
        f"dbname={postgresql.info.dbname} "\
        f"user={postgresql.info.user} "\
        f"password=\"{postgresql.info.password}\" "\
        f"port={postgresql.info.port}"\
        
    print(conn_string)
    pool = psycopg_pool.AsyncConnectionPool(
        conn_string,
        min_size=2,
        max_size=10,
    )
    await pool.wait()
    async with pool.connection() as conn:
        await conn.execute(
            """
            CREATE TABLE query_skeletons (
                hash BYTEA PRIMARY KEY,
                query TEXT NOT NULL
            )
        """
        )
        await conn.execute(
            """
            CREATE TABLE query_logs (
                id UUID PRIMARY KEY DEFAULT gen_random_uuid(),
                query_hash BYTEA REFERENCES query_skeletons(hash),
                subgraph CHAR(46) NOT NULL,
                timestamp TIMESTAMPTZ NOT NULL,
                query_time_ms INTEGER,
                query_variables TEXT
            )
        """
        )
        await conn.execute(
            """
            INSERT INTO query_skeletons (hash, query)
            VALUES ('hash1', 'query getData{ values { id } }'), ('hash2', 'query getInfo{ info { id text} }')
        """
        )
        await conn.execute(
            """
            INSERT INTO query_logs (query_hash, subgraph, timestamp, query_time_ms)
            VALUES ('hash1', 'QmPnu3R7Fm4RmBF21aCYUohDmWbKd3VMXo64ACiRtwUQrn', '2023-05-18T21:47:41+00:00', 100),
            ('hash1', 'QmPnu3R7Fm4RmBF21aCYUohDmWbKd3VMXo64ACiRtwUQrn', '2023-05-18T21:47:41+00:00', 200),
            ('hash2', 'QmTJBvvpknMow6n4YU8R9Swna6N8mHK8N2WufetysBiyuL', '2023-05-18T21:47:41+00:00', 50),
            ('hash1', 'QmTJBvvpknMow6n4YU8R9Swna6N8mHK8N2WufetysBiyuL', '2023-05-18T21:47:41+00:00', 10)
        """)
    async with pool.connection() as conn:
        result = await conn.execute(
            psycopg.sql.SQL("""
            SELECT
                query,
                count_id,
                min_time,
                max_time,
                avg_time,
                stddev_time
            FROM
                query_skeletons
            INNER JOIN
            (
                SELECT
                    query_hash as qhash,
                    count(id) as count_id,
                    Min(query_time_ms) as min_time,
                    Max(query_time_ms) as max_time,
                    Avg(query_time_ms) as avg_time,
                    Stddev(query_time_ms) as stddev_time 
                FROM
                    {}
                WHERE
                    subgraph = 'QmTJBvvpknMow6n4YU8R9Swna6N8mHK8N2WufetysBiyuL'
                    AND query_time_ms IS NOT NULL
                GROUP BY
                    qhash
                HAVING
                    Count(id) >= 0
            ) as query_logs
            ON
                qhash = hash
            ORDER BY
                count_id DESC
        """).format(psycopg.sql.Identifier("query_logs")),
        )
    print(await result.fetchall())
    await pool.close()