Happy birthday!

Author: stympy

.gitignore

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+/.bundle/
+/.yardoc
+/_yardoc/
+/coverage/
+/doc/
+/pkg/
+/spec/reports/
+/tmp/

.travis.yml

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+---
+sudo: false
+language: ruby
+cache: bundler
+rvm:
+  - 2.6.5
+before_install: gem install bundler -v 2.0.2

Gemfile

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+source "https://rubygems.org"
+
+# Specify your gem's dependencies in pg_partition_manager.gemspec
+gemspec

Gemfile.lock

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+PATH
+  remote: .
+  specs:
+    pg_partition_manager (0.1.0)
+      pg (~> 1.0)
+
+GEM
+  remote: https://rubygems.org/
+  specs:
+    ast (2.4.0)
+    jaro_winkler (1.5.3)
+    minitest (5.12.2)
+    parallel (1.18.0)
+    parser (2.6.5.0)
+      ast (~> 2.4.0)
+    pg (1.1.4)
+    rainbow (3.0.0)
+    rake (10.5.0)
+    rubocop (0.72.0)
+      jaro_winkler (~> 1.5.1)
+      parallel (~> 1.10)
+      parser (>= 2.6)
+      rainbow (>= 2.2.2, < 4.0)
+      ruby-progressbar (~> 1.7)
+      unicode-display_width (>= 1.4.0, < 1.7)
+    rubocop-performance (1.4.1)
+      rubocop (>= 0.71.0)
+    ruby-progressbar (1.10.1)
+    standard (0.1.4)
+      rubocop (~> 0.72.0)
+      rubocop-performance (~> 1.4.0)
+    unicode-display_width (1.6.0)
+
+PLATFORMS
+  ruby
+
+DEPENDENCIES
+  bundler (~> 2.0)
+  minitest (~> 5.0)
+  pg_partition_manager!
+  rake (~> 10.0)
+  standard
+
+BUNDLED WITH
+   2.0.2

LICENSE.txt

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+The MIT License (MIT)
+
+Copyright (c) 2019 Honeybadger Industries, LLC
+
+Permission is hereby granted, free of charge, to any person obtaining a copy
+of this software and associated documentation files (the "Software"), to deal
+in the Software without restriction, including without limitation the rights
+to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+copies of the Software, and to permit persons to whom the Software is
+furnished to do so, subject to the following conditions:
+
+The above copyright notice and this permission notice shall be included in
+all copies or substantial portions of the Software.
+
+THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
+THE SOFTWARE.

README.md

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+# PgPartitionManager
+
+Inspired by [pg_partman][1], this gem helps you manage [partitioned tables][2] in PostgreSQL >= 10.
+
+## Installation
+
+Add this line to your application's Gemfile:
+
+```ruby
+gem 'pg_partition_manager'
+```
+
+And then execute:
+
+```shell
+bundle
+```
+
+Or install it yourself as:
+
+```shell
+gem install pg_partition_manager
+```
+
+## Usage
+
+This is meant to be used via a daily cron job, to ensure that new tables are created before they are needed, and old tables are dropped when they aren't needed anymore.
+
+Imagine a cron job like this:
+
+```shell
+@daily cd /app && ./bin/bundle exec ./script/make_partitions.rb
+```
+
+And a Ruby script like this:
+
+```ruby
+#!/usr/bin/env/ruby
+
+require "pg_partition_manager"
+
+PartitionManager::Time.process([
+    {parent_table: "public.events", period: "month", premake: 1, retain: 3},
+    {parent_table: "public.stats", period: "week", premake: 4, retain: 4},
+    {parent_table: "public.observations", period: "day", retain: 7},
+]
+```
+
+If the cron job runs on Monday, September 30th, 2019, and you had created the `events`, `stats`, and `observations` tables in your public schema, the following tables would be created:
+* `public.events_p2019_09_01`
+* `public.events_p2019_10_01`
+* `public.stats_p2019_09_30`
+* `public.stats_p2019_10_07`
+* `public.stats_p2019_10_14`
+* `public.stats_p2019_10_21`
+* `public.observations_p2019_09_30`
+* `public.observations_p2019_10_01`
+* `public.observations_p2019_10_02`
+* `public.observations_p2019_10_03`
+* `public.observations_p2019_10_04`
+
+The `premake` option specifies how many tables to create for dates after the current period, and the `retain` option specifies how many tables to keep for dates before the current period.
+
+This gem uses the [pg gem][3] to connect to your database, and it assumes the DATABASE\_URL environment variable is populated with connection info. If this environment variable isn't defined, a connection to the server running on localhost will be attempted.
+
+
+## Development
+
+After checking out the repo, run `bin/setup` to install dependencies. Then, run `rake test` to run the tests. You can also run `bin/console` for an interactive prompt that will allow you to experiment.
+
+To install this gem onto your local machine, run `bundle exec rake install`. To release a new version, update the version number in `version.rb`, and then run `bundle exec rake release`, which will create a git tag for the version, push git commits and tags, and push the `.gem` file to [rubygems.org](https://rubygems.org).
+
+## Contributing
+
+Bug reports and pull requests are welcome on GitHub at https://github.com/honeybadger-io/pg_partition_manager.
+
+## License
+
+The gem is available as open source under the terms of the [MIT License](https://opensource.org/licenses/MIT).
+
+[1]: https://github.com/pgpartman/pg_partman
+[2]: https://www.postgresql.org/docs/current/ddl-partitioning.html
+[3]: https://rubygems.org/gems/pg

Rakefile

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+require "bundler/gem_tasks"
+require "rake/testtask"
+require "standard/rake"
+
+Rake::TestTask.new(:test) do |t|
+  t.libs << "test"
+  t.libs << "lib"
+  t.test_files = FileList["test/**/*_test.rb"]
+end
+
+task default: [:standard, :test]

lib/pg_partition_manager.rb

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+require "pg_partition_manager/version"
+require "date"
+require "pg"
+
+module PgPartitionManager
+  class Error < StandardError; end
+
+  class Time
+    def initialize(partition, start: Date.today, db: nil)
+      raise ArgumentError, "Period must be 'month', 'week', or 'day'" unless ["month", "week", "day"].include?(partition[:period])
+
+      @partition = partition
+      @start =
+        case partition[:period]
+         when "month"
+           start - start.day + 1 # First day of the current month
+         when "week"
+           start - (start.cwday - 1) # First calendar day of the current week
+         when "day"
+           start
+        end
+      @db = db || PG.connect(ENV["DATABASE_URL"])
+    end
+
+    # Drop the tables that contain data that should be expired based on the
+    # retention period
+    def drop_tables
+      schema, table = @partition[:parent_table].split(".")
+      table_suffix = retention.to_s.tr("-", "_")
+
+      result = @db.exec("select nspname, relname from pg_class c inner join pg_namespace n on n.oid = c.relnamespace where nspname = '#{schema}' and relname like '#{table}_p%' and relkind = 'r' and relname < '#{table}_p#{table_suffix}' order by 1, 2")
+      result.map do |row|
+        child_table = "#{row["nspname"]}.#{row["relname"]}"
+        @db.exec("drop table if exists #{child_table}")
+        child_table
+      end
+    end
+
+    # Create tables to hold future data
+    def create_tables
+      schema, table = @partition[:parent_table].split(".")
+      start = @start
+      stop = period_end(start)
+
+      # Note that this starts in the *current* period, so we start at 0 rather
+      # than 1 for the range, to be sure the current period gets a table *and*
+      # we make the number of desired future tables
+      (0..(@partition[:premake] || 4)).map do |month|
+        child_table = "#{schema}.#{table}_p#{start.to_s.tr("-", "_")}"
+        @db.exec("create table if not exists #{child_table} partition of #{schema}.#{table} for values from ('#{start}') to ('#{stop}')")
+        start = stop
+        stop = period_end(start)
+        child_table
+      end
+    end
+
+    # Return the date for the oldest table to keep, based on the retention setting
+    def retention
+      case @partition[:period]
+      when "month"
+        @start << @partition[:retain] || 6 # Default to 6 months
+      when "week"
+        @start - ((@partition[:retain] || 4) * 7) # Default to 4 weeks
+      when "day"
+        @start - (@partition[:retain] || 7) # Default to 7 days
+      end
+    end
+
+    # Return the begin and end dates for the next partition range
+    def period_end(start)
+      case @partition[:period]
+      when "month"
+        start >> 1
+      when "week"
+        start + 7
+      when "day"
+        start + 1
+      end
+    end
+
+    # A convenience method for doing all the maintenance for a list of partitions
+    def self.process(partitions)
+      partitions.each do |part|
+        pm = new(part)
+        pm.drop_tables
+        pm.create_tables
+      end
+    end
+  end
+end

lib/pg_partition_manager/version.rb

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+module PgPartitionManager
+  VERSION = "0.1.0"
+end

pg_partition_manager.gemspec

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+lib = File.expand_path("lib", __dir__)
+$LOAD_PATH.unshift(lib) unless $LOAD_PATH.include?(lib)
+require "pg_partition_manager/version"
+
+Gem::Specification.new do |spec|
+  spec.name = "pg_partition_manager"
+  spec.version = PgPartitionManager::VERSION
+  spec.authors = ["Benjamin Curtis"]
+  spec.email = ["ben@honeybadger.io"]
+
+  spec.summary = "Manage PostgreSQL table partitions"
+  # spec.description   = %q{TODO: Write a longer description or delete this line.}
+  spec.homepage = "https://github.com/honeybadger-io/pg_partition_manager"
+  spec.license = "MIT"
+
+  spec.metadata["homepage_uri"] = spec.homepage
+  spec.metadata["source_code_uri"] = "https://github.com/honeybadger-io/pg_partition_manager"
+  # spec.metadata["changelog_uri"] = "TODO: Put your gem's CHANGELOG.md URL here."
+
+  # Specify which files should be added to the gem when it is released.
+  # The `git ls-files -z` loads the files in the RubyGem that have been added into git.
+  spec.files = Dir.chdir(File.expand_path("..", __FILE__)) do
+    `git ls-files -z`.split("\x0").reject { |f| f.match(%r{^(test|spec|features)/}) }
+  end
+  spec.bindir = "exe"
+  spec.executables = spec.files.grep(%r{^exe/}) { |f| File.basename(f) }
+  spec.require_paths = ["lib"]
+
+  spec.add_development_dependency "bundler", "~> 2.0"
+  spec.add_development_dependency "rake", "~> 10.0"
+  spec.add_development_dependency "minitest", "~> 5.0"
+  spec.add_development_dependency "standard"
+
+  spec.add_dependency "pg", "~> 1.0"
+end