module PgSaurus::Tools
Provides utility methods to work with PostgreSQL databases. Usage:
PgSaurus::Tools.create_schema "services" # => create new PG schema "services" PgSaurus::Tools.create_schema "nets" PgSaurus::Tools.drop_schema "services" # => remove the schema PgSaurus::Tools.schemas # => ["public", "information_schema", "nets"] PgSaurus::Tools.move_table_to_schema :computers, :nets PgSaurus::Tools.create_view view_name, view_definition # => creates new DB view PgSaurus::Tools.drop_view view_name # => removes the view PgSaurus::Tools.views # => ["x_view", "y_view", "z_view"]
Public Instance Methods
Create a schema if it does not exist yet.
@note
Supports PostgreSQL 9.3+
@return [void]
# File lib/pg_saurus/tools.rb, line 21 def create_schema_if_not_exists(schema_name) unless schemas.include?(schema_name.to_s) sql = %{CREATE SCHEMA "#{schema_name}"} connection.execute sql end end
Creates PostgreSQL view @param [String, Symbol] view_name @param [String] view_definition
# File lib/pg_saurus/tools.rb, line 53 def create_view(view_name, view_definition) sql = "CREATE VIEW #{view_name} AS #{view_definition}" connection.execute sql end
Ensure schema does not exists.
@return [void]
# File lib/pg_saurus/tools.rb, line 31 def drop_schema_if_exists(schema_name) connection.drop_schema(schema_name, if_exists: true) end
Drops PostgreSQL view @param [String, Symbol] view_name
# File lib/pg_saurus/tools.rb, line 60 def drop_view(view_name) sql = "DROP VIEW #{view_name}" connection.execute sql end
Move table to another schema without loosing data, indexes or constraints. @param [String] table table name (schema prefix is allowed) @param [String] new_schema schema where table should be moved to
# File lib/pg_saurus/tools.rb, line 44 def move_table_to_schema(table, new_schema) schema, table = to_schema_and_table(table) sql = %{ALTER TABLE "#{schema}"."#{table}" SET SCHEMA "#{new_schema}"} connection.execute sql end
Returns an array of existing schemas.
# File lib/pg_saurus/tools.rb, line 36 def schemas sql = "SELECT nspname FROM pg_namespace WHERE nspname !~ '^pg_.*' order by nspname" connection.query(sql).flatten end
Extract schema name and table name from qualified table name @param [String, Symbol] table_name table name @return [Array[String, String]] schema and table
# File lib/pg_saurus/tools.rb, line 84 def to_schema_and_table(table_name) table, schema = table_name.to_s.split(".", 2).reverse schema ||= "public" [schema, table] end
Returns an array of existing, non system views.
# File lib/pg_saurus/tools.rb, line 66 def views sql = <<-SQL SELECT table_schema, table_name, view_definition FROM INFORMATION_SCHEMA.views WHERE table_schema NOT IN ('pg_catalog','information_schema') SQL connection.execute sql end
Private Instance Methods
Return database connections
# File lib/pg_saurus/tools.rb, line 76 def connection ActiveRecord::Base.connection end