CollPoll

collpoll

1811 Dictionary in the Vulgar Tongue, by Francis Grose is part of HackerNoon’s Book Blog Post series. You can jump to any chapter in this book here: [ ]. Section O LINK TO TABLE OF LINK Section O O BE JOYFUL. I'll make you sing O be joyful on the other side of your mouth; a threat, implying the party threatened will be made to cry. To sing O be easy; to appear contented when one has cause to complain, and dare not. OAF. A silly fellow. OAFISH. Simple. OAK. A rich maa, a man of good substance and credit. To sport oak; to shut the outward door of a student's room at college. An oaken towel; an oaken cudgel. To rub a man down with an oaken towel; to beat him. OATS. He has sowed his wild oats; he is staid, or sober, having left off his wild tricks. OATHS. The favourite oaths of the thieves of the present day are, "God strike me blind!" "I wish my bloody eyes may drop out if it is not true!" "So help me God!" "Bloody end to me!" OAR. To put in one's oar; to intermeddle, or give an opinion unasked: as, To be sure, you must put in your oar! OBSTROPULOUS. Vulgar misnomer of OBSTREPEROUS: as, I was going my rounds, and found this here gemman very obstropulous, whereof I comprehended him as an auspicious parson. OCCUPY. To occupy a woman; to have carnal knowledge of her. ODDFELLOWS. A convivial society; the introduction to the most noble grand, arrayed in royal robes, is well worth seeing at the price of becoming a member. ODDS PLUT AND HER NAILS. A Welch oath, frequently mentioned in a jocular manner by persons, it is hoped, ignorant of its meaning; which is, By God's blood, and the nails with which he was nailed to the cross. ODD-COME-SHORTLYS. I'll do it one of these odd-come-shortly's; I will do it some time or another. OFFICE. To give the office; to give information, or make signs to the officers to take a thief. OGLES. Eyes. Rum ogles; fine eyes. OIL OF BARLEY, or BARLEY BROTH. Strong beer. OIL OF GLADNESS. I will anoint you with the oil of gladness; ironically spoken for, I will beat you. OIL OF STIRRUP. A dose the cobler gives his wife whenever she is obstropulous. OI POAAOI (Proofreaders Note: Greek Letters). (CAMBRIDGE.) The many; the multitude; who take degrees without being entitled for an honor. All that is REQUIRED, are three books of Euclid, and as far as Quadratic Equation's in Algebra. See PLUCKED. OLD. Ugly. CANT. OLD DOG AT IT. Expert, accustomed. OLD HAND. Knowing or expert in any business. OLD HARRY. A composition used by vintners to adulterate their wines; also the nick-name for the devil. OLD DING. See OLD HAT. OLD MR. GORY. A piece of gold. OLD NICK. The Devil: from NEKEN, the evil spirit of the north. OLD ONE. The Devil. Likewise an expression of quizzical familiarity, as "how d'ye do, OLD ONE?" OLD PEGG. Poor Yorkshire cheese, made of skimmed milk. OLD POGER. The Devil. OLD STAGER. One accustomed to business, one who knows mankind. OLD TOAST. A brisk old fellow. CANT. OLD DOSS. Bridewell. OLIVER'S SCULL. A chamber pot. OLLI COMPOLLI. The name of one of the principal rogues of the canting crew. CANT. OMNIUM GATHERUM. The whole together: jocular imitation of law Latin. ONE IN TEN. A parson: an allusion to his tithes. ONE OF US, or ONE OF MY COUSINS. A woman of the town, a harlot. ONION. A seal. Onion hunters, a class of young thieves who are on the look out for gentlemen who wear their seals suspended on a ribbon, which they cut, and thus secure the seals or other trinkets suspended to the watch. OPEN ARSE. A medlar. See MEDLAR. OPTIME. The senior and junior optimes are the second and last classes of Cambridge honors conferred on taking a degree. That of wranglers is the first. The last junior optime is called the Wooden Spoon. ORGAN. A pipe. Will you cock your organ? will you smoke your pipe? ORTHODOXY AND HETERODOXY. Somebody explained these terms by saying, the first was a man who had a doxy of his own, the second a person who made use of the doxy of another man. OSCHIVES. Bone-handled knives. CANT. OSTLER. Oatstealer. OTTOMY. The vulgar word for a skeleton. OTTOMISED. To be ottomised; to be dissected. You'll be scragged, ottomised, and grin in a glass case: you'll be hanged, anatomised, and your skeleton kept in a glass case at Surgeons' Hall. OVEN. A great mouth; the old woman would never have looked for her daughter in the oven, had she not been there herself. OVERSEER. A man standing in the pillory, is, from his elevated situation, said to be made an overseer. OUT AT HEELS, OR OUT AT ELBOWS. In declining circumstances. OUTRUN THE CONSTABLE. A man who has lived above his means, or income, is said to have outrun the constable. OUTS. A gentleman of three outs. See GENTLEMAN. OWL. To catch the; a trick practised upon ignorant country boobies, who are decoyed into a barn under pretence of catching an owl, where, after divers preliminaries, the joke ends in their having a pail of water poured upon their heads. OWL IN AN IVY BUSH. He looks like an owl in an ivy bush; frequently said of a person with a large frizzled wig, or a woman whose hair is dressed a-la-blowze. OWLERS. Those who smuggle wool over to France. OX HOUSE. He must go through the ox house to bed; a saying of an old fellow who marries a young girl. OYES. Corruption of oyez, proclaimed by the crier of all courts of justice. OYSTER. A gob of thick phlegm, spit by a consumptive man; in law Latin, UNUM VIRIDUM GOBBUM P'S. To mind one's P's and Q's; to be attentive to the main chance. P.P.C. An inscription on the visiting cards of our modern fine gentleman, signifying that they have called POUR PRENDRE CONGE, i.e. 'to take leave,' This has of late been ridiculed by cards inscribed D.I.O. i.e. 'Damme, I'm off.' About HackerNoon Book Series: We bring you the most important technical, scientific, and insightful public domain books. This book is part of the public domain. Urbana, Illinois: Project Gutenberg. Retrieved April 2022 from Grose, Francis. 2004. 1881 Dictionary in the Vulgar Tongue. https://www.gutenberg.org/cache/epub/5402/pg5402.html This eBook is for the use of anyone anywhere at no cost and with almost no restrictions whatsoever. You may copy it, give it away or re-use it under the terms of the Project Gutenberg License included with this eBook or online at , located at . www.gutenberg.org https://www.gutenberg.org/policy/license.html

1811 Dictionary in the Vulgar Tongue: Section O

Crypto Crash? Not Really... 

The Importance of Replication Databases are one of the pillars of any application. If a database server goes down, the whole system will no longer perform its basic services: authenticate users, publish our beloved Hackernoon posts, store comments for the crush’s selfies… This is why designing the system for (the ability of a distributed system to operate continuously without failing for a designated period of time) is essential. High Availability One solution to achieve High availability is to have more components than needed. So for our database system, we can replicate the master database, and if it fails, switch it out for one of the working replicas. Introducing The Solution First, we have to list out our constraints: clients should connect to the database directly and have no interaction with our replication system. our whole system should be very fast and resource-efficient How do we know what part of the database tables has been inserted, deleted, or modified? TRIGGERS! THEY ARE AWESOME !! Database triggers allow us to execute SQL functions whenever an event is received. An event can be any operation such as INSERT, UPDATE, DELETE or TRUNCATE. Triggers are useful for a wide range of cases, like verifying constraints or boosting performance. In our case, we will use triggers to notify our Python listener when data has been removed or added. We define a procedure called that will handle sending notifications about the changes in the database. This is how to define the trigger on the table "users": notify_account_changes() CREATE TRIGGER users_changed
    AFTER INSERT OR UPDATE
    ON users
    FOR EACH ROW
EXECUTE PROCEDURE notify_account_changes(); Okay, now on to the next problem. How the heck can we now notify programs outside our server about these changes? from the PostgreSQL documentation ( ): https://www.postgresql.org/docs/current/sql-notify.html The command sends a notification event together with an optional “payload” string to each client application that has previously executed for the specified channel name in the current database. NOTIFY LISTEN channel In other words, we can have many listeners on a channel by executing . And to send notifications, we use the command or the built-in system function . The payload is a message that we want to send. In our case, the notification payload will include: LISTEN channel_name NOTIFY pg_notify('channel_name', 'payload') TG_TABLE_NAME: name of the table that launched the trigger. TG_OP: the operation that launched the trigger (INSERT, DELETE…). NEW: which is a variable given by the TRIGGER so that we know what the new inserted or updated data. OLD: which is also a variable given by the TRIGGER so that we know the old values before updating or deleting the record. Here’s the code for the notify_account_changes() CREATE OR REPLACE FUNCTION notify_account_changes()
    RETURNS trigger AS
$$
BEGIN
    PERFORM pg_notify(
            'users_changed',
            json_build_object(
                    'table', TG_TABLE_NAME,
                    'operation', TG_OP,
                    'new_record', row_to_json(NEW),
                    'old_record', row_to_json(OLD)
                )::text
        );

    RETURN NEW;
END;
$$ LANGUAGE plpgsql; Now we've received a notification about changes from the triggers. At this stage, we have completed the database side. Listening to the Notifications from Python to connect to the PostgreSQL we are going to use the one and only “psycopg2” library. we can install it using: pip install psycopg2 To connect to the PostgreSQL database and start listening: conn = psycopg2.connect(host="localhost", dbname="DBNAME", user="USERNAME", password="PASSWORD")
conn.set_isolation_level(psycopg2.extensions.ISOLATION_LEVEL_AUTOCOMMIT)
cursor = conn.cursor()
cursor.execute("LISTEN users_changed;") enables us to execute SQL commands like SELECT or INSERT… cursor.execute() Now that we are listening to notifications. How can we parse them? def handle_notify():
    conn.poll()
    for notify in conn.notifies:
        print(notify.payload)
    conn.notifies.clear()

loop = uvloop.new_event_loop()
asyncio.set_event_loop(loop)
loop.add_reader(conn, handle_notify)
loop.run_forever() Here we used asynchronous libraries, and . The line enables us to invoke the function only when the file descriptor (which represents the connection to our database) has an incoming stream of data. After executing uvloop asyncio loop.add_reader(conn, handle_notify) handle_notify() conn INSERT INTO users VALUES (2,'al'); The output is: {
"table" : "users",
"operation" : "INSERT",
"new_record" : {
   "id":2, 
   "name":"al"
    },
"old_record" : null
} Now that we have received all the information we need about database changes. How can we replicate it? Before we do this, we have to address some problems: PostgreSQL NOTIFY queues are not persistent. If we are not listening, notifications will be lost. Having many listeners’ connections can make the database server slower. Introducing RabbitMQ to solve these problems we introduce . RabbitMQ RabbitMQ is a . It gives your applications a common platform to send and receive messages, and your messages a safe place to live until received. messaging broker - an intermediary for messaging RabbitMQ allows us to send messages using queues to different parts of our distributed system. It uses persistent queues to save messages and transactions to ensure that they have been executed properly. So how does RabbitMQ work? Each python script will have its own queue. to send messages to all queues we will send it to a fanout exchange with the script.  the fanout exchange broadcasts every message to all connected queues. changes_listener changes_publisher To use RabbitMQ with python we will use the library pika pip install pika In we will connect to the RabbitMQ server. Then we will create an exchange named “replication”. For each notification received we will broadcast it to all RabbitMQ queues. changes_publisher.py connection = pika.BlockingConnection(pika.ConnectionParameters(host='localhost'))
channel = connection.channel()
channel.exchange_declare(exchange='replication', exchange_type='fanout')

def handle_notify():
    conn.poll()
    for notify in conn.notifies:
        channel.basic_publish(exchange='replication', routing_key='', body=notify.payload)
    conn.notifies.clear() And in our changes_listener.py connection = pika.BlockingConnection(pika.ConnectionParameters(host='localhost'))
channel = connection.channel()
channel.exchange_declare(exchange='replication', exchange_type='fanout')
result = channel.queue_declare(queue='', exclusive=True)
queue_name = result.method.queue
channel.queue_bind(exchange='replication', queue=queue_name)


def callback(channel, method, properties, body):
    op = json.loads(body.decode('utf-8'))
    print(op)


channel.basic_consume(queue=queue_name, on_message_callback=callback, auto_ack=True)
channel.start_consuming() Here we connect to RabbitMQ, declare fanout exchange “replication”, declare temporary queue, bind the queue to the exchange and start consuming messages. on each new message received our callback function will be executed. Executing this SQL query will result in this output from the : UPDATE users SET name='alfonso' WHERE id=2; changes_listener.py {
  'table': 'users',
  'operation': 'UPDATE',
  'new_record': {
    'id': 2,
    'name': 'alfonso'
  },   
  'old_record': {
    'id': 2,
    'name': 'al'
  }
} Writing the changes to the replicas Now that we have received the changes in our python script, all that is left to do is commit these changes. To do this, we will have to change our callback function to generate SQL commands from every received JSON message: def operation_handler(op):
    def handle_insert():
        table, data = op['table'], op['new_record']
        sql = f"""INSERT INTO {table} 
        VALUES ('{data['id']}','{data['name']}');
        """
        return sql
    sql = None
    if op['operation'] == 'INSERT':
        sql = handle_insert()
    # we can add other operation handlers here
    return sql


def callback(channel, method, properties, body):
    op = json.loads(body.decode('utf-8'))
    sql = operation_handler(op)
    cursor.execute(sql) In the callback, when we receive the message, we convert it to a dictionary and pass it to . This function will look at the message and return the appropriate SQL using its values. operation_handler(op) THIS IS IT. WE NOW HAVE ALL THE PIECES WORKING. If we check the replica database after executing a simple SQL query We find this: INSERT INTO users VALUES (2,'al'); PS: PostgreSQL has built-in options for database replication, but our solution enables us to have full control over the replication process. We can replicate only certain tables, certain users or modify the records in any way we want. Final Notes Step by step, we have finished implementing our database replication system. We have gone from configuring triggers and notifications in the database to broadcasting the changes using RabbitMQ to finally writing the changes back into a PostgreSQL replica. Implementing this solution was not easy, it required a lot of pieces, but it is all worth it. Offering users zero downtime is a huge business advantage. Here’s the code for the project https://github.com/Bechir-Brahem/postgres-database-replicator Thank you for reading <3

Stories, News & Mentions about COLLPOLL

Collpoll’s Stories on HackerNoon