🌐 Mailman 3 February 2022 - Python-list - python.org

Re: SQLAlchemy: JSON vs. PickleType vs. raw string for serialised data
by Greg Ewing Feb. 28, 2022

Feb. 28, 2022

On 1/03/22 6:13 am, Albert-Jan Roskam wrote: > I think you need a > BLOB. https://docs.sqlalchemy.org/en/14/core/type_basics.html#sqlalchemy.types.La… That won't help on its own, since you still need to choose a serialisation format to store in the blob. I'd be inclined to use JSON if the data is something that can be easily represented that way. -- Greg

1 0

SQLAlchemy: JSON vs. PickleType vs. raw string for serialised data
by Loris Bennett Feb. 28, 2022

Feb. 28, 2022

Hi, I have an SQLAlchemy class for an event: class UserEvent(Base): __tablename__ = "user_events" id = Column('id', Integer, primary_key=True) date = Column('date', Date, nullable=False) uid = Column('gid', String(64), ForeignKey('users.uid'), nullable=False) info = ?? The event may have arbitrary, but dict-like data associated with it, which I want to add in the field 'info'. This data never needs to be modified, once the event has been inserted into the DB. What type should the info field have? JSON, PickleType, String, or something else? I couldn't find any really reliable sounding information about the relative pros and cons, apart from a Reddit thread claiming that pickled dicts are larger than dicts converted to JSON or String. Cheers, Loris -- This signature is currently under construction.

3 2

Re: SQLAlchemy: JSON vs. PickleType vs. raw string for serialised data
by Robert Latest Feb. 28, 2022

Feb. 28, 2022

Albert-Jan Roskam wrote: > The event may have arbitrary, but dict-like data associated with it, > which I want to add in the field 'info'. This data never needs to be > modified, once the event has been inserted into the DB. > > What type should the info field have? JSON, PickleType, String, or > something else? > > I couldn't find any really reliable sounding information about the > relative > pros and cons, apart from a Reddit thread claiming that pickled dicts > are larger than dicts converted to JSON or String. I've done exactly this. Since my data was strictly ASCII I decided to go for JSON. But in the end you're the only one who can decide this because only you know the data. That's why you won't find any hard and fast rule for this.

1 0

Re: Threading question .. am I doing this right?
by Robert Latest Feb. 28, 2022

Feb. 28, 2022

Chris Angelico wrote: > I'm still curious as to the workload (requests per second), as it might still > be worth going for the feeder model. But if your current system works, then > it may be simplest to debug that rather than change. It is by all accounts a low-traffic situation, maybe one request/second. But the view in question opens four plots on one page, generating four separate requests. So with only two clients and a blocking DB connection, the whole application with eight uwsgi worker threads comes down. Now with the "extra load thread" modification, the app worked fine for several days with only two threads. Out of curiosity I tried the "feeder thread" approach with a dummy thread that just sleeps and logs something every few seconds, ten times total. For some reason it sometimes hangs after eight or nine loops, and then uwsgi cannot restart gracefully probably because it is still waiting for that thread to finish. Also my web app is built around setting up the DB connections in the request context, so using an extra thread outside that context would require doubling some DB infrastructure. Probably not worth it at this point.

1 0

Re: C is it always faster than nump?
by Dennis Lee Bieber Feb. 28, 2022

Feb. 28, 2022

On Fri, 25 Feb 2022 21:44:14 -0800, Dan Stromberg <drsalists(a)gmail.com> declaimed the following: >Fortran, (still last I heard) did not support pointers, which gives Fortran >compilers the chance to exploit a very nice class of optimizations you >can't use nearly as well in languages with pointers. > Haven't looked much at Fortran-90/95 then... Variable declaration gained a POINTER qualifier, and there is an ALLOCATE intrinsic to obtain memory. And with difficulty one could get the result in DEC/VMS FORTRAN-77 since DEC implemented (across all their language compilers) intrinsics controlling how arguments are passed -- overriding the language native passing: CALL XYZ(%val(M)) would actually pass the value of M, not Fortran default address-of, with the result that XYZ would use that value /as/ the address of the actual argument. (Others were %ref() and %descr() -- descriptor being a small structure with the address reference along with, say, upper/lower bounds; often used for strings). -- Wulfraed Dennis Lee Bieber AF6VN wlfraed(a)ix.netcom.com http://wlfraed.microdiversity.freeddns.org/

2 1

When to use SQLAlchemy listen events
by Loris Bennett Feb. 28, 2022

Feb. 28, 2022

Hi, I am wondering whether SQLAlchemy listen events are appropriate for the following situation: I have a table containing users and a table for events related to users class User(Base): __tablename__ = "users" uid = Column('uid', String(64), primary_key=True) gid = Column('gid', String(64), ForeignKey('groups.gid'), nullable=False) lang = Column('lang', String(2)) class UserEvent(Base): __tablename__ = "user_events" id = Column('id', Integer, primary_key=True) date = Column('date', Date, nullable=False) uid = Column('gid', String(64), ForeignKey('users.uid'), nullable=False) comment = Column('comment', String(256)) (There are also analogous tables for groups and group events). The functions provided by the interface are things like the following add_user(user, group, lang) move_user(user, group) delete_user(user) warn_user(user, reason) Whereas 'add/move/delete_user' result in changes to the table 'users', 'warn_user' does not. All should produce entries in the table 'user_events'. There could be more functions similar to 'warn_user' that only create an entry in 'user_events'. Potentially there could be a lot more of these than the 'user'-table-changing type. It seems like for the first three functions, capturing the resulting database changes in the table 'user_events' would be a standard use-case for listen event. However, the 'warn_user' function is different. So can/should I shoehorn the 'warn_user' function to being like the others three and use listen events, or should I just come up with my own mechanism which will allow any function just to add an entry to the events table? Cheers, Loris -- This signature is currently under construction.

1 1

Best way to check if there is internet?
by Abdur-Rahmaan Janhangeer Feb. 28, 2022

Feb. 28, 2022

Greetings, Using the standard library or 3rd party libraries, what's the best way to check if there is internet? Checking if google.com is reachable is good but I wonder if there is a more native, protocol-oriented way of knowing? Even this URL recommends checking if a domain is up as a way to check for internet connectivity: https://www.ibm.com/support/pages/checking-network-connectivity-when-using-… Kind Regards, Abdur-Rahmaan Janhangeer about <https://compileralchemy.github.io/> | blog <https://www.pythonkitchen.com> github <https://github.com/Abdur-RahmaanJ> Mauritius

14 34

One-liner to merge lists?
by Frank Millman Feb. 27, 2022

Feb. 27, 2022

Hi all I think this should be a simple one-liner, but I cannot figure it out. I have a dictionary with a number of keys, where each value is a single list - >>> d = {1: ['aaa', 'bbb', 'ccc'], 2: ['fff', 'ggg']} I want to combine all values into a single list - >>> ans = ['aaa', 'bbb', 'ccc', 'fff', 'ggg'] I can do this - >>> a = [] >>> for v in d.values(): ... a.extend(v) ... >>> a ['aaa', 'bbb', 'ccc', 'fff', 'ggg'] I can also do this - >>> from itertools import chain >>> a = list(chain(*d.values())) >>> a ['aaa', 'bbb', 'ccc', 'fff', 'ggg'] >>> Is there a simpler way? Thanks Frank Millman

9 18

PYT - How can I subscribe to a topic in the mailing list?
by vanyp Feb. 27, 2022

Feb. 27, 2022

And h*ow do I set the topic in my messages?*

4 4

Re: Getting Syslog working on OSX Monterey
by Dennis Lee Bieber Feb. 27, 2022

Feb. 27, 2022

On Sun, 27 Feb 2022 08:34:21 -0800, Philip Bloom <philip.bloom(a)applovin.com> declaimed the following: > >sys_handler = SysLogHandler(address='/var/run/syslog') As I read the documentation, the address is supposed to be the NETWORK address of the machine to receive the log messages... https://docs.python.org/3/library/logging.handlers.html#sysloghandler >#sys_handler.encodePriority(SysLogHandler.LOG_USER, SysLogHandler.LOG_ALERT) ># Tried with the above, but didn't make a difference. Neither did not >defining the address and letting it go to local host. >sys_handler.setFormatter(syslog_format) >root_logger.addHandler(sys_handler) > >logging.critical("This is a test") >logging.error("This is a test error") >logging.info("Still a test") >logging.debug("Testy test") > >Using command line: Oddly, this gets to Console.Apps messages from device >reliably, though doesn't get picked up by syslog -w or get received by the >ASL config redirect: >syslog -s -l error -k Message "appName: this is a test2" >syslog -s -l notice -k Message "appName: this is a test3" > >ASL configuration, which is loaded according to syslog -config: >> /var/log/appName/appName.log mode=0640 compress format=std rotate=seq >file_max=50M all_max=500M >? [CA= Sender appName] file /var/log/appName/appName.log > >My end goal is really to get just a working python logging -> >var/log/appname/appname.log again so glad to just be pointed in the right >direction if way off base. -- Wulfraed Dennis Lee Bieber AF6VN wlfraed(a)ix.netcom.com http://wlfraed.microdiversity.freeddns.org/

2 2