How to create a new table from select statement in sqlalchemy?

Question

I am using sqlalchemy\'s core features to write some abstraction layer. The layer itself needs to be able to create tables from select statements.

Sample code:

Answer 1

Normally we'd subclass DDLElement, but as you'd like to use bound parameters, we'll stay within the SQL element system:

from sqlalchemy.ext.compiler import compiles
from sqlalchemy.sql.expression import ClauseElement, Executable


class CreateTableAs(Executable, ClauseElement):

    def __init__(self, name, query):
        self.name = name
        self.query = query


@compiles(CreateTableAs, "postgresql")
def _create_table_as(element, compiler, **kw):
    return "CREATE TABLE %s AS %s" % (
        element.name,
        compiler.process(element.query)
    )

if __name__ == '__main__':
    from sqlalchemy import Table, Column, Integer, \
        MetaData, create_engine, select

    m = MetaData()
    t = Table('t', m, Column('x', Integer), Column('y', Integer))

    e = create_engine("postgresql://scott:tiger@localhost/test", echo=True)
    c = e.connect()
    trans = c.begin()

    t.create(c)
    c.execute(
        t.insert(),
        [{"x": 1, "y": 2}, {"x": 11, "y": 3}]
    )

    s = select([t]).where(t.c.x > 10)

    c.execute(CreateTableAs('t2', s))

    assert c.execute("select x, y from t2").fetchall() == [(11, 3)]
    trans.rollback()

output:

2015-06-01 11:42:55,982 INFO sqlalchemy.engine.base.Engine BEGIN (implicit)
2015-06-01 11:42:55,982 INFO sqlalchemy.engine.base.Engine 
CREATE TABLE t (
    x INTEGER, 
    y INTEGER
)


2015-06-01 11:42:55,982 INFO sqlalchemy.engine.base.Engine {}
2015-06-01 11:42:55,985 INFO sqlalchemy.engine.base.Engine INSERT INTO t (x, y) VALUES (%(x)s, %(y)s)
2015-06-01 11:42:55,986 INFO sqlalchemy.engine.base.Engine ({'y': 2, 'x': 1}, {'y': 3, 'x': 11})
2015-06-01 11:42:55,988 INFO sqlalchemy.engine.base.Engine CREATE TABLE t2 AS SELECT t.x, t.y 
FROM t 
WHERE t.x > %(x_1)s
2015-06-01 11:42:55,988 INFO sqlalchemy.engine.base.Engine {'x_1': 10}
2015-06-01 11:42:55,996 INFO sqlalchemy.engine.base.Engine select x, y from t2
2015-06-01 11:42:55,996 INFO sqlalchemy.engine.base.Engine {}
2015-06-01 11:42:55,997 INFO sqlalchemy.engine.base.Engine ROLLBACK