Matrika: A Next Generation Decentralized Database

matrika

A next generation decentralized database.

In matrika, databases and indexes are merkle graphs (DAGs) implemented on Prolly Trees (Probablistic B-Trees) in IPLD.

Data is written to CAR files that are pushed to web3.storage and made available in IPFS. Optionally, these CAR files could be written to other IPFS nodes and Filecoin.

CLI

The main interface at this time is the CLI. Commands are namespaced into the following categories:

  • kv

Key Value Store

The key value store is an append only log of changes to a map (implemented as a prolly tree).

It is an efficient key value store that scales to an indefinite size. Concurrent changes between different actors can be reconciled and most conflicts automatically resolved.

cli.js <command>

Commands:
  cli.js kv-create <json>           Create new database from JSON string map
  cli.js kv-ls [start] [end]        List the keys in a database
  cli.js kv-get <key>               Read single key
  cli.js kv-set <key> <value-json>  Write single key

Options:
  --help     Show help                                                 [boolean]
  --version  Show version number                                       [boolean]

Download details:
Author: mikeal
Source code: https://github.com/mikeal/matrika
License:

#next #nextjs #react #javascript #web3

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Matrika: A Next Generation Decentralized Database
Ruth  Nabimanya

Ruth Nabimanya

1620633584

System Databases in SQL Server

Introduction

In SSMS, we many of may noticed System Databases under the Database Folder. But how many of us knows its purpose?. In this article lets discuss about the System Databases in SQL Server.

System Database

Fig. 1 System Databases

There are five system databases, these databases are created while installing SQL Server.

  • Master
  • Model
  • MSDB
  • Tempdb
  • Resource
Master
  • This database contains all the System level Information in SQL Server. The Information in form of Meta data.
  • Because of this master database, we are able to access the SQL Server (On premise SQL Server)
Model
  • This database is used as a template for new databases.
  • Whenever a new database is created, initially a copy of model database is what created as new database.
MSDB
  • This database is where a service called SQL Server Agent stores its data.
  • SQL server Agent is in charge of automation, which includes entities such as jobs, schedules, and alerts.
TempDB
  • The Tempdb is where SQL Server stores temporary data such as work tables, sort space, row versioning information and etc.
  • User can create their own version of temporary tables and those are stored in Tempdb.
  • But this database is destroyed and recreated every time when we restart the instance of SQL Server.
Resource
  • The resource database is a hidden, read only database that holds the definitions of all system objects.
  • When we query system object in a database, they appear to reside in the sys schema of the local database, but in actually their definitions reside in the resource db.

#sql server #master system database #model system database #msdb system database #sql server system databases #ssms #system database #system databases in sql server #tempdb system database

Django-allauth: A simple Boilerplate to Setup Authentication

Django-Authentication 

A simple Boilerplate to Setup Authentication using Django-allauth, with a custom template for login and registration using django-crispy-forms.

Getting Started

Prerequisites

  • Python 3.8.6 or higher

Project setup

# clone the repo
$ git clone https://github.com/yezz123/Django-Authentication

# move to the project folder
$ cd Django-Authentication

Creating virtual environment

  • Create a virtual environment for this project:
# creating pipenv environment for python 3
$ virtualenv venv

# activating the pipenv environment
$ cd venv/bin #windows environment you activate from Scripts folder

# if you have multiple python 3 versions installed then
$ source ./activate

Configured Enviromment

Environment variables

SECRET_KEY = #random string
DEBUG = #True or False
ALLOWED_HOSTS = #localhost
DATABASE_NAME = #database name (You can just use the default if you want to use SQLite)
DATABASE_USER = #database user for postgres
DATABASE_PASSWORD = #database password for postgres
DATABASE_HOST = #database host for postgres
DATABASE_PORT = #database port for postgres
ACCOUNT_EMAIL_VERIFICATION = #mandatory or optional
EMAIL_BACKEND = #email backend
EMAIL_HOST = #email host
EMAIL_HOST_PASSWORD = #email host password
EMAIL_USE_TLS = # if your email use tls
EMAIL_PORT = #email port

change all the environment variables in the .env.sample and don't forget to rename it to .env.

Run the project

After Setup the environment, you can run the project using the Makefile provided in the project folder.

help:
 @echo "Targets:"
 @echo "    make install" #install requirements
 @echo "    make makemigrations" #prepare migrations
 @echo "    make migrations" #migrate database
 @echo "    make createsuperuser" #create superuser
 @echo "    make run_server" #run the server
 @echo "    make lint" #lint the code using black
 @echo "    make test" #run the tests using Pytest

Preconfigured Packages

Includes preconfigured packages to kick start Django-Authentication by just setting appropriate configuration.

PackageUsage
django-allauthIntegrated set of Django applications addressing authentication, registration, account management as well as 3rd party (social) account authentication.
django-crispy-formsdjango-crispy-forms provides you with a crispy filter and {% crispy %} tag that will let you control the rendering behavior of your Django forms in a very elegant and DRY way.

Contributing

  • Django-Authentication is a simple project, so you can contribute to it by just adding your code to the project to improve it.
  • If you have any questions, please feel free to open an issue or create a pull request.

Download Details:
Author: yezz123
Source Code: https://github.com/yezz123/Django-Authentication
License: MIT License

#django #python 

 iOS App Dev

iOS App Dev

1625133780

SingleStore: The One Stop Shop For Everything Data

  • SingleStore works toward helping businesses embrace digital innovation by operationalising “all data through one platform for all the moments that matter”

The pandemic has brought a period of transformation across businesses globally, pushing data and analytics to the forefront of decision making. Starting from enabling advanced data-driven operations to creating intelligent workflows, enterprise leaders have been looking to transform every part of their organisation.

SingleStore is one of the leading companies in the world, offering a unified database to facilitate fast analytics for organisations looking to embrace diverse data and accelerate their innovations. It provides an SQL platform to help companies aggregate, manage, and use the vast trove of data distributed across silos in multiple clouds and on-premise environments.

**Your expertise needed! **Fill up our quick Survey

#featured #data analytics #data warehouse augmentation #database #database management #fast analytics #memsql #modern database #modernising data platforms #one stop shop for data #singlestore #singlestore data analytics #singlestore database #singlestore one stop shop for data #singlestore unified database #sql #sql database

amelia jones

1591340335

How To Take Help Of Referencing Generator

APA Referencing Generator

Many students use APA style as the key citation style in their assignment in university or college. Although, many people find it quite difficult to write the reference of the source. You ought to miss the names and dates of authors. Hence, APA referencing generator is important for reducing the burden of students. They can now feel quite easy to do the assignments on time.

The functioning of APA referencing generator

If you are struggling hard to write the APA referencing then you can take the help of APA referencing generator. It will create an excellent list. You are required to enter the information about the source. Just ensure that the text is credible and original. If you will copy references then it is a copyright violation.

You can use a referencing generator in just a click. It will generate the right references for all the sources. You are required to organize in alphabetical order. The generator will make sure that you will get good grades.

How to use APA referencing generator?

Select what is required to be cited such as journal, book, film, and others. You can choose the type of required citations list and enter all the required fields. The fields are dates, author name, title, editor name, and editions, name of publishers, chapter number, page numbers, and title of journals. You can click for reference to be generated and you will get the desired result.

Chicago Referencing Generator

Do you require the citation style? You can rely on Chicago Referencing Generator and will ensure that you will get the right citation in just a click. The generator is created to provide solutions to students to cite their research paper in Chicago style. It has proved to be the quickest and best citation generator on the market. The generator helps to sort the homework issues in few seconds. It also saves a lot of time and energy.

This tool helps researchers, professional writers, and students to manage and generate text citation essays. It will help to write Chicago style in a fast and easy way. It also provides details and directions for formatting and cites resources.

So, you must stop wasting the time and can go for Chicago Referencing Generator or APA referencing generator. These citation generators will help to solve the problem of citation issues. You can easily create citations by using endnotes and footnotes.

So, you can generate bibliographies, references, in-text citations, and title pages. These are fully automatic referencing style. You are just required to enter certain details about the citation and you will get the citation in the proper and required format.

So, if you are feeling any problem in doing assignment then you can take the help of assignment help.
If you require help for Assignment then livewebtutors is the right place for you. If you see our prices, you will observe that they are actually very affordable. Also, you can always expect a discount. Our team is capable and versatile enough to offer you exactly what you need, the best services for the prices you can afford.

read more:- Are you struggling to write a bibliography? Use Harvard referencing generator

#apa referencing generator #harvard referencing generator #chicago referencing generator #mla referencing generator #deakin referencing generator #oxford referencing generator

Royce  Reinger

Royce Reinger

1658977500

A Ruby Library for Generating Text with Recursive Template Grammars

Calyx

Calyx provides a simple API for generating text with declarative recursive grammars.

Install

Command Line

gem install calyx

Gemfile

gem 'calyx'

Examples

The best way to get started quickly is to install the gem and run the examples locally.

Any Gradient

Requires Roda and Rack to be available.

gem install roda

Demonstrates how to use Calyx to construct SVG graphics. Any Gradient generates a rectangle with a linear gradient of random colours.

Run as a web server and preview the output in a browser (http://localhost:9292):

ruby examples/any_gradient.rb

Or generate SVG files via a command line pipe:

ruby examples/any_gradient > gradient1.xml

Tiny Woodland Bot

Requires the Twitter client gem and API access configured for a specific Twitter handle.

gem install twitter

Demonstrates how to use Calyx to make a minimal Twitter bot that periodically posts unique tweets. See @tiny_woodland on Twitter and the writeup here.

TWITTER_CONSUMER_KEY=XXX-XXX
TWITTER_CONSUMER_SECRET=XXX-XXX
TWITTER_ACCESS_TOKEN=XXX-XXX
TWITTER_CONSUMER_SECRET=XXX-XXX
ruby examples/tiny_woodland_bot.rb

Faker

Faker is a popular library for generating fake names and associated sample data like internet addresses, company names and locations.

This example demonstrates how to use Calyx to reproduce the same functionality using custom lists defined in a YAML configuration file.

ruby examples/faker.rb

Usage

Require the library and inherit from Calyx::Grammar to construct a set of rules to generate a text.

require 'calyx'

class HelloWorld < Calyx::Grammar
  start 'Hello world.'
end

To generate the text itself, initialize the object and call the generate method.

hello = HelloWorld.new
hello.generate
# > "Hello world."

Obviously, this hardcoded sentence isn’t very interesting by itself. Possible variations can be added to the text by adding additional rules which provide a named set of text strings. The rule delimiter syntax ({}) can be used to substitute the generated content of other rules.

class HelloWorld < Calyx::Grammar
  start '{greeting} world.'
  greeting 'Hello', 'Hi', 'Hey', 'Yo'
end

Each time #generate runs, it evaluates the tree and randomly selects variations of rules to construct a resulting string.

hello = HelloWorld.new

hello.generate
# > "Hi world."

hello.generate
# > "Hello world."

hello.generate
# > "Yo world."

By convention, the start rule specifies the default starting point for generating the final text. You can start from any other named rule by passing it explicitly to the generate method.

class HelloWorld < Calyx::Grammar
  hello 'Hello world.'
end

hello = HelloWorld.new
hello.generate(:hello)

Block Constructors

As an alternative to subclassing, you can also construct rules unique to an instance by passing a block when initializing the class:

hello = Calyx::Grammar.new do
  start '{greeting} world.'
  greeting 'Hello', 'Hi', 'Hey', 'Yo'
end

hello.generate

Template Expressions

Basic rule substitution uses single curly brackets as delimiters for template expressions:

fruit = Calyx::Grammar.new do
  start '{colour} {fruit}'
  colour 'red', 'green', 'yellow'
  fruit 'apple', 'pear', 'tomato'
end

6.times { fruit.generate }
# => "yellow pear"
# => "red apple"
# => "green tomato"
# => "red pear"
# => "yellow tomato"
# => "green apple"

Nesting and Substitution

Rules are recursive. They can be arbitrarily nested and connected to generate larger and more complex texts.

class HelloWorld < Calyx::Grammar
  start '{greeting} {world_phrase}.'
  greeting 'Hello', 'Hi', 'Hey', 'Yo'
  world_phrase '{happy_adj} world', '{sad_adj} world', 'world'
  happy_adj 'wonderful', 'amazing', 'bright', 'beautiful'
  sad_adj 'cruel', 'miserable'
end

Nesting and hierarchy can be manipulated to balance consistency with novelty. The exact same word atoms can be combined in a variety of ways to produce strikingly different resulting texts.

module HelloWorld
  class Sentiment < Calyx::Grammar
    start '{happy_phrase}', '{sad_phrase}'
    happy_phrase '{happy_greeting} {happy_adj} world.'
    happy_greeting 'Hello', 'Hi', 'Hey', 'Yo'
    happy_adj 'wonderful', 'amazing', 'bright', 'beautiful'
    sad_phrase '{sad_greeting} {sad_adj} world.'
    sad_greeting 'Goodbye', 'So long', 'Farewell'
    sad_adj 'cruel', 'miserable'
  end

  class Mixed < Calyx::Grammar
    start '{greeting} {adj} world.'
    greeting 'Hello', 'Hi', 'Hey', 'Yo', 'Goodbye', 'So long', 'Farewell'
    adj 'wonderful', 'amazing', 'bright', 'beautiful', 'cruel', 'miserable'
  end
end

Random Sampling

By default, the outcomes of generated rules are selected with Ruby’s built-in pseudorandom number generator (as seen in methods like Kernel.rand and Array.sample). To seed the random number generator, pass in an integer seed value as the first argument to the constructor:

grammar = Calyx::Grammar.new(seed: 12345) do
  # rules...
end

Alternatively, you can pass a preconfigured instance of Ruby’s stdlib Random class:

random = Random.new(12345)

grammar = Calyx::Grammar.new(rng: random) do
  # rules...
end

When a random seed isn’t supplied, Time.new.to_i is used as the default seed, which makes each run of the generator relatively unique.

Weighted Choices

Choices can be weighted so that some rules have a greater probability of expanding than others.

Weights are defined by passing a hash instead of a list of rules where the keys are strings or symbols representing the grammar rules and the values are weights.

Weights can be represented as floats, integers or ranges.

  • Floats must be in the interval 0..1 and the given weights for a production must sum to 1.
  • Ranges must be contiguous and cover the entire interval from 1 to the maximum value of the largest range.
  • Integers (Fixnums) will produce a distribution based on the sum of all given numbers, with each number being a fraction of that sum.

The following definitions produce an equivalent weighting of choices:

Calyx::Grammar.new do
  start 'heads' => 1, 'tails' => 1
end

Calyx::Grammar.new do
  start 'heads' => 0.5, 'tails' => 0.5
end

Calyx::Grammar.new do
  start 'heads' => 1..5, 'tails' => 6..10
end

Calyx::Grammar.new do
  start 'heads' => 50, 'tails' => 50
end

There’s a lot of interesting things you can do with this. For example, you can model the triangular distribution produced by rolling 2d6:

Calyx::Grammar.new do
  start(
    '2' => 1,
    '3' => 2,
    '4' => 3,
    '5' => 4,
    '6' => 5,
    '7' => 6,
    '8' => 5,
    '9' => 4,
    '10' => 3,
    '11' => 2,
    '12' => 1
  )
end

Or reproduce Gary Gygax’s famous generation table from the original Dungeon Master’s Guide (page 171):

Calyx::Grammar.new do
  start(
    :empty => 0.6,
    :monster => 0.1,
    :monster_treasure => 0.15,
    :special => 0.05,
    :trick_trap => 0.05,
    :treasure => 0.05
  )
  empty 'Empty'
  monster 'Monster Only'
  monster_treasure 'Monster and Treasure'
  special 'Special'
  trick_trap 'Trick/Trap.'
  treasure 'Treasure'
end

String Modifiers

Dot-notation is supported in template expressions, allowing you to call any available method on the String object returned from a rule. Formatting methods can be chained arbitrarily and will execute in the same way as they would in native Ruby code.

greeting = Calyx::Grammar.new do
  start '{hello.capitalize} there.', 'Why, {hello} there.'
  hello 'hello', 'hi'
end

4.times { greeting.generate }
# => "Hello there."
# => "Hi there."
# => "Why, hello there."
# => "Why, hi there."

You can also extend the grammar with custom modifiers that provide useful formatting functions.

Filters

Filters accept an input string and return the transformed output:

greeting = Calyx::Grammar.new do
  filter :shoutycaps do |input|
    input.upcase
  end

  start '{hello.shoutycaps} there.', 'Why, {hello.shoutycaps} there.'
  hello 'hello', 'hi'
end

4.times { greeting.generate }
# => "HELLO there."
# => "HI there."
# => "Why, HELLO there."
# => "Why, HI there."

Mappings

The mapping shortcut allows you to specify a map of regex patterns pointing to their resulting substitution strings:

green_bottle = Calyx::Grammar.new do
  mapping :pluralize, /(.+)/ => '\\1s'
  start 'One green {bottle}.', 'Two green {bottle.pluralize}.'
  bottle 'bottle'
end

2.times { green_bottle.generate }
# => "One green bottle."
# => "Two green bottles."

Modifier Mixins

In order to use more intricate rewriting and formatting methods in a modifier chain, you can add methods to a module and embed it in a grammar using the modifier classmethod.

Modifier methods accept a single argument representing the input string from the previous step in the expression chain and must return a string, representing the modified output.

module FullStop
  def full_stop(input)
    input << '.'
  end
end

hello = Calyx::Grammar.new do
  modifier FullStop
  start '{hello.capitalize.full_stop}'
  hello 'hello'
end

hello.generate
# => "Hello."

To share custom modifiers across multiple grammars, you can include the module in Calyx::Modifiers. This will make the methods available to all subsequent instances:

module FullStop
  def full_stop(input)
    input << '.'
  end
end

class Calyx::Modifiers
  include FullStop
end

Monkeypatching String

Alternatively, you can combine methods from existing Gems that monkeypatch String:

require 'indefinite_article'

module FullStop
  def full_stop
    self << '.'
  end
end

class String
  include FullStop
end

noun_articles = Calyx::Grammar.new do
  start '{fruit.with_indefinite_article.capitalize.full_stop}'
  fruit 'apple', 'orange', 'banana', 'pear'
end

4.times { noun_articles.generate }
# => "An apple."
# => "An orange."
# => "A banana."
# => "A pear."

Memoized Rules

Rule expansions can be ‘memoized’ so that multiple references to the same rule return the same value. This is useful for picking a noun from a list and reusing it in multiple places within a text.

The @ sigil is used to mark memoized rules. This evaluates the rule and stores it in memory the first time it’s referenced. All subsequent references to the memoized rule use the same stored value.

# Without memoization
grammar = Calyx::Grammar.new do
  start '{name} <{name.downcase}>'
  name 'Daenerys', 'Tyrion', 'Jon'
end

3.times { grammar.generate }
# => Daenerys <jon>
# => Tyrion <daenerys>
# => Jon <tyrion>

# With memoization
grammar = Calyx::Grammar.new do
  start '{@name} <{@name.downcase}>'
  name 'Daenerys', 'Tyrion', 'Jon'
end

3.times { grammar.generate }
# => Tyrion <tyrion>
# => Daenerys <daenerys>
# => Jon <jon>

Note that the memoization symbol can only be used on the right hand side of a production rule.

Unique Rules

Rule expansions can be marked as ‘unique’, meaning that multiple references to the same rule always return a different value. This is useful for situations where the same result appearing twice would appear awkward and messy.

Unique rules are marked by the $ sigil.

grammar = Calyx::Grammar.new do
  start "{$medal}, {$medal}, {$medal}"
  medal 'Gold', 'Silver', 'Bronze'
end

grammar.generate
# => Silver, Bronze, Gold

Dynamically Constructing Rules

Template expansions can be dynamically constructed at runtime by passing a context map of rules to the #generate method:

class AppGreeting < Calyx::Grammar
  start 'Hi {username}!', 'Welcome back {username}...', 'Hola {username}'
end

context = {
  username: UserModel.username
}

greeting = AppGreeting.new
greeting.generate(context)

External File Formats

In addition to defining grammars in pure Ruby, you can load them from external JSON and YAML files:

hello = Calyx::Grammar.load('hello.yml')
hello.generate

The format requires a flat map with keys representing the left-hand side named symbols and the values representing the right hand side substitution rules.

In JSON:

{
  "start": "{greeting} world.",
  "greeting": ["Hello", "Hi", "Hey", "Yo"]
}

In YAML:

---
start: "{greeting} world."
greeting:
  - Hello
  - Hi
  - Hey
  - Yo

Accessing the Raw Generated Tree

Calling #evaluate on the grammar instance will give you access to the raw generated tree structure before it gets flattened into a string.

The tree is encoded as an array of nested arrays, with the leading symbols labeling the choices and rules selected, and the trailing terminal leaves encoding string values.

This may not make a lot of sense unless you’re familiar with the concept of s-expressions. It’s a fairly speculative feature at this stage, but it leads to some interesting possibilities.

grammar = Calyx::Grammar.new do
  start 'Riddle me ree.'
end

grammar.evaluate
# => [:start, [:choice, [:concat, [[:atom, "Riddle me ree."]]]]]

Roadmap

Rough plan for stabilising the API and features for a 1.0 release.

VersionFeatures planned
0.6block constructor
0.7support for template context map passed to generate
0.8method missing metaclass API
0.9return grammar tree from #evaluate, with flattened string from #generate being separate
0.10inject custom string functions for parameterised rules, transforms and mappings
0.11support YAML format (and JSON?)
0.12API documentation
0.13Support for unique rules
0.14Support for Ruby 2.4
0.15Options config and ‘strict mode’ error handling
0.16Improve representation of weighted probability selection
0.17Return result object from #generate calls

Credits

Author & Maintainer

Contributors

Author: Maetl
Source Code: https://github.com/maetl/calyx 
License: MIT license

#ruby #text