# Copyright 2022 The SQLNet Company GmbH
#
# This file is licensed under the Elastic License 2.0 (ELv2).
# Refer to the LICENSE.txt file in the root of the repository
# for details.
#
"""
Creates a new DuckDB database connection.
"""
import os
from typing import Any, Dict, List, Optional
import getml.communication as comm
from getml import constants
from .connection import Connection
[docs]def connect_duckdb(
name: Optional[str] = None,
time_formats: Optional[List[str]] = None,
conn_id: str = "default",
):
"""Creates a new DuckDB database connection.
DuckDB is a popular database that focuses on analytical queries.
It is faster than databases like PostgreSQL, but less suitable for massive
parallel access.
Because of its focus on analytical queries, it executes the features
generated by getML much faster than any of the other supported database.
Args:
name (str, optional):
Name of the DuckDB file. If the file does not exist, it
will be created. Set to None for a purely in-memory DuckDB
database.
time_formats (List[str], optional):
The list of formats tried when parsing time stamps.
The formats are allowed to contain the following
special characters:
* %w - abbreviated weekday (Mon, Tue, ...)
* %W - full weekday (Monday, Tuesday, ...)
* %b - abbreviated month (Jan, Feb, ...)
* %B - full month (January, February, ...)
* %d - zero-padded day of month (01 .. 31)
* %e - day of month (1 .. 31)
* %f - space-padded day of month ( 1 .. 31)
* %m - zero-padded month (01 .. 12)
* %n - month (1 .. 12)
* %o - space-padded month ( 1 .. 12)
* %y - year without century (70)
* %Y - year with century (1970)
* %H - hour (00 .. 23)
* %h - hour (00 .. 12)
* %a - am/pm
* %A - AM/PM
* %M - minute (00 .. 59)
* %S - second (00 .. 59)
* %s - seconds and microseconds (equivalent to %S.%F)
* %i - millisecond (000 .. 999)
* %c - centisecond (0 .. 9)
* %F - fractional seconds/microseconds (000000 - 999999)
* %z - time zone differential in ISO 8601 format (Z or +NN.NN)
* %Z - time zone differential in RFC format (GMT or +NNNN)
* %% - percent sign
conn_id (str, optional):
The name to be used to reference the connection.
If you do not pass anything, this will create a new default connection.
Note:
By selecting an existing table of your database in
:func:`~getml.DataFrame.from_db` function, you can create
a new :class:`~getml.DataFrame` containing all its data.
Alternatively you can use the
:meth:`~.getml.DataFrame.read_db` and
:meth:`~.getml.DataFrame.read_query` methods to replace
the content of the current :class:`~getml.DataFrame`
instance or append further rows based on either a table or a
specific query.
You can also write your results back into the DuckDB
database. By passing the name for the destination table to
:meth:`getml.Pipeline.transform`, the features
generated from your raw data will be written back. Passing
them into :meth:`getml.Pipeline.predict`, instead,
makes predictions of the target variables to new, unseen data
and stores the result into the corresponding table.
"""
time_formats = time_formats or constants.TIME_FORMATS
cmd: Dict[str, Any] = {}
if name is not None:
cmd["name_"] = os.path.abspath(name)
cmd["type_"] = "Database.new"
cmd["db_"] = "duckdb"
cmd["time_formats_"] = time_formats
cmd["conn_id_"] = conn_id
with comm.send_and_get_socket(cmd) as sock:
# The password is usually sent separately,
# so it doesn't
# end up in the logs. However, DuckDB does not
# need a password, so we just send a dummy.
comm.send_string(sock, "none")
msg = comm.recv_string(sock)
if msg != "Success!":
comm.engine_exception_handler(msg)
return Connection(conn_id=conn_id)