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"""
Creates a new PostgreSQL database connection.
"""
import getml.communication as comm
import getml.constants as constants
from .connection import Connection
[docs]def connect_postgres(
dbname,
user,
password,
host=None,
hostaddr=None,
port=5432,
time_formats=None,
conn_id="default",
):
"""
Creates a new PostgreSQL database connection.
But first, make sure your database is running and you can reach it
from via your command line.
Args:
dbname (str):
The name of the database to which you want to connect.
user (str):
User name with which to log into the PostgreSQL database.
password (str):
Password with which to log into the PostgreSQL database.
host (str):
Host of the PostgreSQL database.
hostaddr (str):
IP address of the PostgreSQL database.
This should be in the standard IPv4 address format, e.g., 172.28.40.9.
If your machine supports IPv6, you can also use those addresses.
TCP/IP communication is always used when a nonempty string is specified
for this parameter.
port(int, optional):
Port of the PostgreSQL database.
The default port used by PostgreSQL is 5432.
If you do not know, which port to use, type the following into your
PostgreSQL client
.. code-block:: sql
SELECT setting FROM pg_settings WHERE name = 'port';
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 PostgreSQL
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
# -------------------------------------------
# Prepare command.
cmd = dict()
cmd["name_"] = ""
cmd["type_"] = "Database.new"
cmd["db_"] = "postgres"
if host is not None:
cmd["host_"] = host
if hostaddr is not None:
cmd["hostaddr_"] = hostaddr
cmd["port_"] = port
cmd["dbname_"] = dbname
cmd["user_"] = user
cmd["time_formats_"] = time_formats
cmd["conn_id_"] = conn_id
# -------------------------------------------
# Send JSON command to engine.
sock = comm.send_and_get_socket(cmd)
# -------------------------------------------
# The password is sent separately, so it doesn't
# end up in the logs.
comm.send_string(sock, password)
# -------------------------------------------
# Make sure that everything went well.
msg = comm.recv_string(sock)
if msg != "Success!":
comm.engine_exception_handler(msg)
# -------------------------------------------
return Connection(conn_id=conn_id)