def _create_csv(cur: psycopg2.extensions.cursor, filename: str,
select_stmnt: str):
"""Create or update given csv file with db data for given select statement."""
with open(f'exports/{filename}.csv', 'wb') as csvfile:
cur.copy_expert(f'COPY ({select_stmnt}) to stdout with csv header',
csvfile)
return f'{filename}.csv'
def view_contents(cursor: psycopg2.extensions.cursor, view: str, timestamp: int) -> str:
"""Return True if a SELECT from the VIEW matches the expected string."""
stream = io.StringIO()
query = f"COPY (SELECT * FROM {view} WHERE mz_logical_timestamp() > {timestamp}) TO STDOUT"
try:
cursor.copy_expert(query, stream) # type: ignore
except psycopg2.errors.InternalError_: # type: ignore
# The view is not yet ready to be queried
raise ViewNotReady()
return stream.getvalue().strip()
def view_matches(cursor: psycopg2.extensions.cursor, view: str,
expected: str) -> bool:
"""Return True if a SELECT from the VIEW matches the expected string."""
stream = io.StringIO()
try:
cursor.copy_expert(f"COPY (SELECT * FROM {view}) TO STDOUT", stream)
except psycopg2.errors.InternalError_:
# The view is not yet ready to be queried
return False
return stream.getvalue() == expected
