### Install Dependencies with Bundler

Source: https://github.com/ged/ruby-pg/blob/master/README.md

Run this command after checking out the source code to install all necessary project dependencies.

```bash
$ bundle install
```

--------------------------------

### Install PG Gem with Specific Config

Source: https://github.com/ged/ruby-pg/blob/master/README.md

Install the PG gem, forcing the use of the source gem and specifying the path to pg_config. Useful when binary gems are not suitable or available.

```bash
gem install pg -- --with-pg-config=<path to pg_config>
```

--------------------------------

### Install pg Gem with Specific pg_config Path

Source: https://github.com/ged/ruby-pg/blob/master/README-OS_X.rdoc

When installing the 'pg' gem, specify the path to the 'pg_config' tool using the --with-pg-config option if it's not in your default PATH or if you need to use a specific PostgreSQL installation.

```bash
gem install -- --with-pg-config=/opt/local/lib/postgresql90/bin/pg_config
```

--------------------------------

### Connect and Query PostgreSQL

Source: https://github.com/ged/ruby-pg/blob/master/README.md

Connect to a PostgreSQL database and execute a query to retrieve connection activity. Requires the 'pg' gem to be installed.

```ruby
#!/usr/bin/env ruby

require 'pg'

# Output a table of current connections to the DB
conn = PG.connect( dbname: 'sales' )
conn.exec( "SELECT * FROM pg_stat_activity" ) do |result|
  puts "     PID | User             | Query"
  result.each do |row|
    puts " %7d | %-16s | %s " %
      row.values_at('pid', 'usename', 'query')
  end
end
```

--------------------------------

### Install Specific Legacy Version of 'postgres' Gem

Source: https://github.com/ged/ruby-pg/blob/master/misc/postgres/README.txt

Use this command to install a specific legacy version of the 'postgres' gem if required for older projects. Ensure you uninstall any newer versions afterward.

```bash
gem install postgres -v '0.7.9.2008.01.28'
```

```bash
gem uninstall postgres -v '>0.7.9.2008.01.28'
```

--------------------------------

### Enable Basic Type Casting for Results and Queries

Source: https://github.com/ged/ruby-pg/blob/master/README.md

Configure type mapping for both retrieving results and sending query parameters. The first example shows how result values are cast, and the second demonstrates parameter casting.

```ruby
conn.type_map_for_results = PG::BasicTypeMapForResults.new conn
# ... this works for result value mapping:
conn.exec("select 1, now(), '{2,3}'::int[]").values
    # => [[1, 2014-09-21 20:51:56 +0200, [2, 3]]]
```

```ruby
conn.type_map_for_queries = PG::BasicTypeMapForQueries.new conn
# ... and this for param value mapping:
conn.exec_params("SELECT $1::text, $2::text, $3::text", [1, 1.23, [2,3]]).values
    # => [["1", "1.2300000000000000E+00", "{2,3}"]]
```

--------------------------------

### Install Specific Version of ruby-pg

Source: https://github.com/ged/ruby-pg/blob/master/misc/ruby-pg/README.txt

Use this command to install a specific, older version of the ruby-pg gem if required for legacy applications. Ensure you are aware of the version number needed.

```bash
gem install ruby-pg -v '0.7.9.2008.01.28'
```

--------------------------------

### Build 'pg' Gem with Custom PostgreSQL Path

Source: https://github.com/ged/ruby-pg/blob/master/README-Windows.rdoc

Use this command when 'pg_config.exe' is not in your PATH. Adjust the path to your PostgreSQL installation, ensuring you use short path names to avoid issues with spaces.

```bash
rake --with-pg-dir=c:/progra~1/postgr~1/8.3
```

--------------------------------

### Install pg Gem with ARCHFLAGS for Universal Binaries

Source: https://github.com/ged/ruby-pg/blob/master/README-OS_X.rdoc

If you encounter issues with universal binaries during 'pg' gem installation on MacOS X, set the ARCHFLAGS environment variable to specify the desired architecture, such as x86_64.

```bash
sudo env ARCHFLAGS='-arch x86_64' gem install pg
```

--------------------------------

### Check OpenSSL Library Linking on MacOS X

Source: https://github.com/ged/ruby-pg/blob/master/README-OS_X.rdoc

Use 'otool -L' to verify which SSL library your Ruby installation is linked against. This is crucial for preventing segfaults when using 'pg' and the 'openssl' extension simultaneously.

```bash
$ otool -L /System/Library/Frameworks/Ruby.framework/Versions\
  /1.8/usr/lib/ruby/1.8/universal-darwin11.0/openssl.bundle

/System/Library/Frameworks/Ruby.framework/Versions/1.8/usr/\
    lib/ruby/1.8/universal-darwin11.0/openssl.bundle:
    /System/Library/Frameworks/Ruby.framework/Versions/1.8/
        usr/lib/libruby.1.dylib (compatibility version 1.8.0, \
        current version 1.8.7)
    /usr/lib/libssl.0.9.8.dylib (compatibility version 0.9.8, \
        current version 0.9.8)
    /usr/lib/libcrypto.0.9.8.dylib (compatibility version 0.9.8, \
        current version 0.9.8)
    /usr/lib/libSystem.B.dylib (compatibility version 1.0.0, \
        current version 159.0.0)
```

--------------------------------

### Uninstall Newer Versions of ruby-pg

Source: https://github.com/ged/ruby-pg/blob/master/misc/ruby-pg/README.txt

If you have a newer version of ruby-pg installed and need to use an older one, use this command to uninstall any versions greater than the specified one. This is crucial for ensuring compatibility with legacy systems.

```bash
gem uninstall ruby-pg -v '>0.7.9.2008.01.28'
```

--------------------------------

### Build Native Binary 'pg' Gems for Windows

Source: https://github.com/ged/ruby-pg/blob/master/README-Windows.rdoc

This command initiates the process of building native binary gems for Windows using Docker. It downloads a Docker image, builds OpenSSL and PostgreSQL within the container, and then compiles the gem for supported Ruby versions.

```bash
rake gem:native
```

--------------------------------

### Run Tests

Source: https://github.com/ged/ruby-pg/blob/master/README.md

Execute the project's tests and specs against the PostgreSQL version configured by `pg_config --bindir`.

```bash
$ rake test
```

--------------------------------

### Compile Extension

Source: https://github.com/ged/ruby-pg/blob/master/README.md

Compile the extension files for the project.

```bash
$ rake compile
```

--------------------------------

### Generate API Documentation

Source: https://github.com/ged/ruby-pg/blob/master/README.md

Generate the API documentation for the project using the rake task.

```bash
$ rake docs
```

--------------------------------

### Run Specific Test with PostgreSQL Version

Source: https://github.com/ged/ruby-pg/blob/master/README.md

Run a specific test file and line number against a particular PostgreSQL version by prepending the desired PostgreSQL bin directory to the PATH.

```bash
$ PATH=/usr/lib/postgresql/14/bin:$PATH rspec -Ilib -fd spec/pg/connection_spec.rb:455
```

--------------------------------

### Configure Bundler for Platforms

Source: https://github.com/ged/ruby-pg/blob/master/README.md

Lock down specific platforms for the bundle and package all platform-specific gems. Ensures consistent builds across different environments.

```bash
bundle lock --add-platform x86_64-linux
bundle lock --add-platform arm64-darwin
bundle lock --add-platform x64-mingw-ucrt
bundle lock --add-platform ruby
bundle package --all-platforms
```

--------------------------------

### Clean Extension Files

Source: https://github.com/ged/ruby-pg/blob/master/README.md

Use this rake task to clean up extension files, packaging files, and test databases. It's useful for switching between different PostgreSQL versions.

```bash
$ rake clean
```

--------------------------------

### Compile pg Gem with ARCHFLAGS

Source: https://github.com/ged/ruby-pg/blob/master/README-OS_X.rdoc

When building the 'pg' gem from source on MacOS X, you can explicitly set the ARCHFLAGS environment variable to ensure compatibility with specific architectures.

```bash
rake compile ARCHFLAGS="-arch x86_64"
```

--------------------------------

### Force Source Gem Usage in Gemfile

Source: https://github.com/ged/ruby-pg/blob/master/README.md

Force the usage of the source gem for the 'pg' gem within a Gemfile. Use this if binary gems are causing issues or do not support a required feature.

```ruby
gem "pg", force_ruby_platform: true
```

--------------------------------

### Add PG Dependency with Pessimistic Version Constraint

Source: https://github.com/ged/ruby-pg/blob/master/README.md

Specify a dependency on the 'pg' gem in a gemspec file using a pessimistic version constraint. This follows Semantic Versioning principles for reliable updates.

```ruby
spec.add_dependency 'pg', '~> 1.0'
```

=== COMPLETE CONTENT === This response contains all available snippets from this library. No additional content exists. Do not make further requests.