def exists(self, connection: Connection, cursor: Cursor) -> bool:
""" Checks if this view exists """
exists_sql, exists_params = self._exists_sql(connection)
the_view = self._execute(connection, cursor, exists_sql, exists_params)
# check if the value returned is not None
return cursor.fetchone() is not None
def _quote_values(self, connection: Connection, cursor: Cursor,
values: list[Any]) -> list[str]:
""" Quotes a list of values for inclusion in a different sql value """
# make a statement SELECT quote(%s), quote(%s), ... for each of the values
sql = "SELECT {}".format(", ".join(["quote(%s)"] * len(values)))
cursor.execute(sql, values)
return cursor.fetchone()
def do_batch_update(
cursor: CursorWrapper,
table: str,
assignments: List[Composable],
batch_size: int = 10000,
sleep: float = 0.1,
) -> None: # nocoverage
# The string substitution below is complicated by our need to
# support multiple PostgreSQL versions.
stmt = SQL("""
UPDATE {}
SET {}
WHERE id >= %s AND id < %s
""").format(
Identifier(table),
SQL(", ").join(assignments),
)
cursor.execute(
SQL("SELECT MIN(id), MAX(id) FROM {}").format(Identifier(table)))
(min_id, max_id) = cursor.fetchone()
if min_id is None:
return
print(f"\n Range of rows to update: [{min_id}, {max_id}]")
while min_id <= max_id:
lower = min_id
upper = min_id + batch_size
print(f" Updating range [{lower},{upper})")
cursor.execute(stmt, [lower, upper])
min_id = upper
time.sleep(sleep)
# Once we've finished, check if any new rows were inserted to the table
if min_id > max_id:
cursor.execute(
SQL("SELECT MAX(id) FROM {}").format(Identifier(table)))
(max_id, ) = cursor.fetchone()
print(" Finishing...", end="")