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Sequel::Postgres::DatabaseMethods

Methods shared by Database instances that connect to PostgreSQL.

Public Instance Methods

commit_prepared_transaction(transaction_id) click to toggle source

Commit an existing prepared transaction with the given transaction identifier string.

# File lib/sequel/adapters/shared/postgres.rb, line 167
def commit_prepared_transaction(transaction_id)
  run("COMMIT PREPARED #{literal(transaction_id)}")
end
create_function(name, definition, opts={}) click to toggle source

Creates the function in the database. Arguments:

  • name : name of the function to create

  • definition : string definition of the function, or object file for a dynamically loaded C function.

  • opts : options hash:

    • :args : function arguments, can be either a symbol or string specifying a type or an array of 1-3 elements:

      • element 1 : argument data type

      • element 2 : argument name

      • element 3 : argument mode (e.g. in, out, inout)

    • :behavior : Should be IMMUTABLE, STABLE, or VOLATILE. PostgreSQL assumes VOLATILE by default.

    • :cost : The estimated cost of the function, used by the query planner.

    • :language : The language the function uses. SQL is the default.

    • :link_symbol : For a dynamically loaded see function, the function's link symbol if different from the definition argument.

    • :returns : The data type returned by the function. If you are using OUT or INOUT argument modes, this is ignored. Otherwise, if this is not specified, void is used by default to specify the function is not supposed to return a value.

    • :rows : The estimated number of rows the function will return. Only use if the function returns SETOF something.

    • :security_definer : Makes the privileges of the function the same as the privileges of the user who defined the function instead of the privileges of the user who runs the function. There are security implications when doing this, see the PostgreSQL documentation.

    • :set : Configuration variables to set while the function is being run, can be a hash or an array of two pairs. search_path is often used here if :security_definer is used.

    • :strict : Makes the function return NULL when any argument is NULL.

# File lib/sequel/adapters/shared/postgres.rb, line 191
def create_function(name, definition, opts={})
  self << create_function_sql(name, definition, opts)
end
create_language(name, opts={}) click to toggle source

Create the procedural language in the database. Arguments:

  • name : Name of the procedural language (e.g. plpgsql)

  • opts : options hash:

    • :handler : The name of a previously registered function used as a call handler for this language.

    • :replace: Replace the installed language if it already exists (on PostgreSQL 9.0+).

    • :trusted : Marks the language being created as trusted, allowing unprivileged users to create functions using this language.

    • :validator : The name of previously registered function used as a validator of functions defined in this language.

# File lib/sequel/adapters/shared/postgres.rb, line 202
def create_language(name, opts={})
  self << create_language_sql(name, opts)
end
create_trigger(table, name, function, opts={}) click to toggle source

Create a trigger in the database. Arguments:

  • table : the table on which this trigger operates

  • name : the name of this trigger

  • function : the function to call for this trigger, which should return type trigger.

  • opts : options hash:

    • :after : Calls the trigger after execution instead of before.

    • :args : An argument or array of arguments to pass to the function.

    • :each_row : Calls the trigger for each row instead of for each statement.

    • :events : Can be :insert, :update, :delete, or an array of any of those. Calls the trigger whenever that type of statement is used. By default, the trigger is called for insert, update, or delete.

# File lib/sequel/adapters/shared/postgres.rb, line 216
def create_trigger(table, name, function, opts={})
  self << create_trigger_sql(table, name, function, opts)
end
database_type() click to toggle source

PostgreSQL uses the :postgres database type.

# File lib/sequel/adapters/shared/postgres.rb, line 221
def database_type
  :postgres
end
drop_function(name, opts={}) click to toggle source

Drops the function from the database. Arguments:

  • name : name of the function to drop

  • opts : options hash:

    • :args : The arguments for the function. See create_function_sql.

    • :cascade : Drop other objects depending on this function.

    • :if_exists : Don't raise an error if the function doesn't exist.

# File lib/sequel/adapters/shared/postgres.rb, line 231
def drop_function(name, opts={})
  self << drop_function_sql(name, opts)
end
drop_language(name, opts={}) click to toggle source

Drops a procedural language from the database. Arguments:

  • name : name of the procedural language to drop

  • opts : options hash:

    • :cascade : Drop other objects depending on this function.

    • :if_exists : Don't raise an error if the function doesn't exist.

# File lib/sequel/adapters/shared/postgres.rb, line 240
def drop_language(name, opts={})
  self << drop_language_sql(name, opts)
end
drop_trigger(table, name, opts={}) click to toggle source

Drops a trigger from the database. Arguments:

  • table : table from which to drop the trigger

  • name : name of the trigger to drop

  • opts : options hash:

    • :cascade : Drop other objects depending on this function.

    • :if_exists : Don't raise an error if the function doesn't exist.

# File lib/sequel/adapters/shared/postgres.rb, line 250
def drop_trigger(table, name, opts={})
  self << drop_trigger_sql(table, name, opts)
end
indexes(table, opts={}) click to toggle source

Use the pg_* system tables to determine indexes on a table

# File lib/sequel/adapters/shared/postgres.rb, line 255
def indexes(table, opts={})
  m = output_identifier_meth
  im = input_identifier_meth
  schema, table = schema_and_table(table)
  range = 0...32
  attnums = server_version >= 80100 ? SQL::Function.new(:ANY, :ind__indkey) : range.map{|x| SQL::Subscript.new(:ind__indkey, [x])}
  ds = metadata_dataset.
    from(:pg_class___tab).
    join(:pg_index___ind, :indrelid=>:oid, im.call(table)=>:relname).
    join(:pg_class___indc, :oid=>:indexrelid).
    join(:pg_attribute___att, :attrelid=>:tab__oid, :attnum=>attnums).
    filter(:indc__relkind=>'i', :ind__indisprimary=>false, :indexprs=>nil, :indpred=>nil).
    order(:indc__relname, range.map{|x| [SQL::Subscript.new(:ind__indkey, [x]), x]}.case(32, :att__attnum)).
    select(:indc__relname___name, :ind__indisunique___unique, :att__attname___column)
  
  ds.join!(:pg_namespace___nsp, :oid=>:tab__relnamespace, :nspname=>schema.to_s) if schema
  ds.filter!(:indisvalid=>true) if server_version >= 80200
  ds.filter!(:indisready=>true, :indcheckxmin=>false) if server_version >= 80300
  
  indexes = {}
  ds.each do |r|
    i = indexes[m.call(r[:name])] ||= {:columns=>[], :unique=>r[:unique]}
    i[:columns] << m.call(r[:column])
  end
  indexes
end
locks() click to toggle source

Dataset containing all current database locks

# File lib/sequel/adapters/shared/postgres.rb, line 283
def locks
  dataset.from(:pg_class).join(:pg_locks, :relation=>:relfilenode).select(:pg_class__relname, Sequel::SQL::ColumnAll.new(:pg_locks))
end
notify(channel, opts={}) click to toggle source

Notifies the given channel. See the PostgreSQL NOTIFY documentation. Options:

:payload

The payload string to use for the NOTIFY statement. Only supported in PostgreSQL 9.0+.

:server

The server to which to send the NOTIFY statement, if the sharding support is being used.

# File lib/sequel/adapters/shared/postgres.rb, line 293
def notify(channel, opts={})
  execute_ddl("NOTIFY #{channel}#{", #{literal(opts[:payload].to_s)}" if opts[:payload]}", opts)
end
primary_key(table, opts={}) click to toggle source

Return primary key for the given table.

# File lib/sequel/adapters/shared/postgres.rb, line 298
def primary_key(table, opts={})
  quoted_table = quote_schema_table(table)
  return @primary_keys[quoted_table] if @primary_keys.include?(quoted_table)
  @primary_keys[quoted_table] = if conn = opts[:conn]
    conn.primary_key(*schema_and_table(table))
  else
    synchronize(opts[:server]){|con| con.primary_key(*schema_and_table(table))}
  end
end
primary_key_sequence(table, opts={}) click to toggle source

Return the sequence providing the default for the primary key for the given table.

# File lib/sequel/adapters/shared/postgres.rb, line 309
def primary_key_sequence(table, opts={})
  quoted_table = quote_schema_table(table)
  return @primary_key_sequences[quoted_table] if @primary_key_sequences.include?(quoted_table)
  @primary_key_sequences[quoted_table] = if conn = opts[:conn]
    conn.sequence(*schema_and_table(table))
  else
    synchronize(opts[:server]){|con| con.sequence(*schema_and_table(table))}
  end
end
reset_primary_key_sequence(table) click to toggle source

Reset the primary key sequence for the given table, baseing it on the maximum current value of the table's primary key.

# File lib/sequel/adapters/shared/postgres.rb, line 321
def reset_primary_key_sequence(table)
  pk = SQL::Identifier.new(primary_key(table))
  return unless seq = primary_key_sequence(table)
  db = self
  seq_ds = db.from(seq.lit)
  get{setval(seq, db[table].select{coalesce(max(pk)+seq_ds.select{:increment_by}, seq_ds.select(:min_value))}, false)}
end
rollback_prepared_transaction(transaction_id) click to toggle source

Rollback an existing prepared transaction with the given transaction identifier string.

# File lib/sequel/adapters/shared/postgres.rb, line 331
def rollback_prepared_transaction(transaction_id)
  run("ROLLBACK PREPARED #{literal(transaction_id)}")
end
serial_primary_key_options() click to toggle source

PostgreSQL uses SERIAL psuedo-type instead of AUTOINCREMENT for managing incrementing primary keys.

# File lib/sequel/adapters/shared/postgres.rb, line 337
def serial_primary_key_options
  {:primary_key => true, :serial => true, :type=>Integer}
end
server_version(server=nil) click to toggle source

The version of the PostgreSQL server, used for determining capability.

# File lib/sequel/adapters/shared/postgres.rb, line 342
def server_version(server=nil)
  return @server_version if @server_version
  @server_version = synchronize(server) do |conn|
    (conn.server_version rescue nil) if conn.respond_to?(:server_version)
  end
  unless @server_version
    @server_version = if m = /PostgreSQL (\d+)\.(\d+)(?:(?:rc\d+)|\.(\d+))?/.match(fetch('SELECT version()').single_value)
      (m[1].to_i * 10000) + (m[2].to_i * 100) + m[3].to_i
    else
      0
    end
  end
  @server_version
end
supports_create_table_if_not_exists?() click to toggle source

PostgreSQL supports CREATE TABLE IF NOT EXISTS on 9.1+

# File lib/sequel/adapters/shared/postgres.rb, line 365
def supports_create_table_if_not_exists?
  server_version >= 90100
end
supports_prepared_transactions?() click to toggle source

PostgreSQL supports prepared transactions (two-phase commit) if max_prepared_transactions is greater than 0.

# File lib/sequel/adapters/shared/postgres.rb, line 359
def supports_prepared_transactions?
  return @supports_prepared_transactions if defined?(@supports_prepared_transactions)
  @supports_prepared_transactions = self['SHOW max_prepared_transactions'].get.to_i > 0
end
supports_savepoints?() click to toggle source

PostgreSQL supports savepoints

# File lib/sequel/adapters/shared/postgres.rb, line 370
def supports_savepoints?
  true
end
supports_transaction_isolation_levels?() click to toggle source

PostgreSQL supports transaction isolation levels

# File lib/sequel/adapters/shared/postgres.rb, line 375
def supports_transaction_isolation_levels?
  true
end
tables(opts={}, &block) click to toggle source

Array of symbols specifying table names in the current database. The dataset used is yielded to the block if one is provided, otherwise, an array of symbols of table names is returned.

Options:

  • :schema - The schema to search (default_schema by default)

  • :server - The server to use

# File lib/sequel/adapters/shared/postgres.rb, line 386
def tables(opts={}, &block)
  pg_class_relname('r', opts, &block)
end
views(opts={}) click to toggle source

Array of symbols specifying view names in the current database.

Options:

  • :schema - The schema to search (default_schema by default)

  • :server - The server to use

# File lib/sequel/adapters/shared/postgres.rb, line 395
def views(opts={})
  pg_class_relname('v', opts)
end

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