Module: PgSaurus::Tools
Overview
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"]
Instance Method Summary collapse
-
#create_schema_if_not_exists(schema_name) ⇒ void
Create a schema if it does not exist yet.
-
#create_view(view_name, view_definition) ⇒ Object
Creates PostgreSQL view.
-
#drop_schema_if_exists(schema_name) ⇒ void
Ensure schema does not exists.
-
#drop_view(view_name) ⇒ Object
Drops PostgreSQL view.
-
#move_table_to_schema(table, new_schema) ⇒ Object
Move table to another schema without loosing data, indexes or constraints.
-
#schemas ⇒ Object
Returns an array of existing schemas.
-
#to_schema_and_table(table_name) ⇒ Array[String, String]
Extract schema name and table name from qualified table name.
-
#views ⇒ Object
Returns an array of existing, non system views.
Instance Method Details
#create_schema_if_not_exists(schema_name) ⇒ void
Supports PostgreSQL 9.3+
This method returns an undefined value.
Create a schema if it does not exist yet.
21 22 23 24 25 26 |
# 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 |
#create_view(view_name, view_definition) ⇒ Object
Creates PostgreSQL view
53 54 55 56 |
# 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 |
#drop_schema_if_exists(schema_name) ⇒ void
This method returns an undefined value.
Ensure schema does not exists.
31 32 33 |
# File 'lib/pg_saurus/tools.rb', line 31 def drop_schema_if_exists(schema_name) connection.drop_schema(schema_name, if_exists: true) end |
#drop_view(view_name) ⇒ Object
Drops PostgreSQL view
60 61 62 63 |
# 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_schema(table, new_schema) ⇒ Object
Move table to another schema without loosing data, indexes or constraints.
44 45 46 47 48 |
# 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 |
#schemas ⇒ Object
Returns an array of existing schemas.
36 37 38 39 |
# 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 |
#to_schema_and_table(table_name) ⇒ Array[String, String]
Extract schema name and table name from qualified table name
84 85 86 87 88 |
# 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 |
#views ⇒ Object
Returns an array of existing, non system views.
66 67 68 69 70 71 72 73 |
# 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 |