a script to read db tables in memory, truncate tables, and insert back the data - for stupid performance tests (used sqlalchemy, psycopg2 and python 3.5)

benchmark.py

# http://dabeaz.blogspot.mk/2010/02/context-manager-for-timing-benchmarks.html
import time
class benchmark(object):
    def __init__(self,name):
        self.name = name
    def __enter__(self):
        self.start = time.time()
    def __exit__(self,ty,val,tb):
        end = time.time()
        print("%s : %0.3f seconds" % (self.name, end-self.start))
        return False

dbtest.py

# -*- coding: utf-8 -*-
from benchmark import benchmark

from sqlalchemy.engine import reflection
from sqlalchemy import select, func, MetaData, create_engine

dburl = 'postgres://localhost/'
engine = create_engine(dburl, client_encoding='utf8')

meta = MetaData()
meta.reflect(bind=engine)

def list_tables():
    for table in meta.sorted_tables:
        q = select([func.count()]).select_from(table)
        r = engine.execute(q)
        print(table.name, r.scalar(), end=' | ', sep=': ')
    print()

with benchmark('--- list database tables'):
    list_tables()

data = {}
with benchmark('--- read from all tables'):
    for table in meta.sorted_tables:
        r = engine.execute(table.select())
        rows = [ dict(row.items()) for row in r ]
        data[table.name] = rows


with benchmark('--- delete from all tables'):
    for table in reversed(meta.sorted_tables):
        engine.execute(table.delete())


with benchmark("--- insert into all tables"):
    for table in meta.sorted_tables:
        with benchmark("---    insert into: %s" % table.name):
            rows = data[table.name]
            if rows:
                q = table.insert().values(rows)
                r = engine.execute(q)

with benchmark('--- list database tables again'):
    list_tables()