Python (falcon) transition is read only

Question

I'm running into a strange error -psycopg2.errors.ReadOnlySqlTransaction: transaction is read-only when i'm trying to read data from my redshift database from my python application. I'm not trying to modify the database so i'm not sure why this happens. I'm using a postgresql plugin (psycopg2) version 2.8.4. And python version 3.5 -I have lot of other queries that i'm running in the same approach and they work without a problem, so i'm a little confused what could be causing this.

Here is the query i'm running

SELECT
    stat_date,
    age,
    name,
    SUM(spent) as spent,
FROM (

    SELECT stat_date, age,name, spent
    FROM mview_a
    WHERE id in ('id1', 'id2')

UNION ALL

    SELECT stat_date, age,name, spent
    FROM mview_b
    WHERE id in ('id1', 'id2')

UNION ALL

    SELECT stat_date, age,name, spent
    FROM mview_c
    WHERE id in ('id1', 'id2')

UNION ALL

    SELECT stat_date, age,name, spent
    FROM view_d (combination of multiple mviews)
    WHERE id in ('id1', 'id2')

UNION ALL

    SELECT stat_date, age,name, spent
    FROM mview_e
    WHERE id in ('id1', 'id2')

)

GROUP BY 1;

And this is how i pass my query along with params

dw = self.get_conn(conn)
results = dw.fetch_all_query(query, params=params, **kwargs)

And the database calls fails on this line from psycopg2 package.

self.execute_query(q, dict_cursor=dict_cursor, params=params,
                   readonly=readonly, autocommit=autocommit, conn=False)

Answer 1

In my case, the issue was happening because one of the mviews i use is a combination (union all) of two different mviews and for some reason, psql was throwing an error saying transaction is read only. The error message was pretty unclear to solve this.