Module: Sequel::Postgres::DatabaseMethods

Included in:
DataObjects::Postgres::DatabaseMethods, JDBC::Postgres::DatabaseMethods, Database, Swift::Postgres::DatabaseMethods
Defined in:
lib/sequel/adapters/shared/postgres.rb

Overview

Methods shared by Database instances that connect to PostgreSQL.

Constant Summary collapse

EXCLUDE_SCHEMAS = 
/pg_*|information_schema/i
PREPARED_ARG_PLACEHOLDER = 
LiteralString.new('$').freeze
RE_CURRVAL_ERROR = 
/currval of sequence "(.*)" is not yet defined in this session|relation "(.*)" does not exist/.freeze
SYSTEM_TABLE_REGEXP = 
/^pg|sql/.freeze

Instance Method Summary collapse

Instance Method Details

#commit_prepared_transaction(transaction_id) ⇒ Object

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



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# 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 = {}) ⇒ Object

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.



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# 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 = {}) ⇒ Object

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.



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# 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 = {}) ⇒ Object

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.



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# 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 ⇒ Object

PostgreSQL uses the :postgres database type.



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# File 'lib/sequel/adapters/shared/postgres.rb', line 221

def database_type
  :postgres
end

#drop_function(name, opts = {}) ⇒ Object

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.



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# 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 = {}) ⇒ Object

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.



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# File 'lib/sequel/adapters/shared/postgres.rb', line 240

def drop_language(name, opts={})
  self << drop_language_sql(name, opts)
end

#drop_table(*names) ⇒ Object

Remove the cached entries for primary keys and sequences when dropping a table.



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# File 'lib/sequel/adapters/shared/postgres.rb', line 245

def drop_table(*names)
  names.each do |name|
    name = quote_schema_table(name)
    @primary_keys.delete(name)
    @primary_key_sequences.delete(name)
  end
  super
end

#drop_trigger(table, name, opts = {}) ⇒ Object

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.



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# File 'lib/sequel/adapters/shared/postgres.rb', line 260

def drop_trigger(table, name, opts={})
  self << drop_trigger_sql(table, name, opts)
end

#indexes(table, opts = {}) ⇒ Object

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



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# File 'lib/sequel/adapters/shared/postgres.rb', line 265

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 ⇒ Object

Dataset containing all current database locks



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# File 'lib/sequel/adapters/shared/postgres.rb', line 293

def locks
  dataset.from(:pg_class).join(:pg_locks, :relation=>:relfilenode).select(:pg_class__relname, Sequel::SQL::ColumnAll.new(:pg_locks))
end

#primary_key(table, opts = {}) ⇒ Object

Return primary key for the given table.



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# 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 = {}) ⇒ Object

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



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# 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) ⇒ Object

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



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# 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) ⇒ Object

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



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# 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 ⇒ Object

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



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# 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) ⇒ Object

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



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# 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
    m = /PostgreSQL (\d+)\.(\d+)(?:(?:rc\d+)|\.(\d+))?/.match(fetch('SELECT version()').single_value)
    @server_version = (m[1].to_i * 10000) + (m[2].to_i * 100) + m[3].to_i
  end
  @server_version
end

#supports_prepared_transactions? ⇒ Boolean

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

Returns:

  • (Boolean) 


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# File 'lib/sequel/adapters/shared/postgres.rb', line 356

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? ⇒ Boolean

PostgreSQL supports savepoints

Returns:

  • (Boolean) 


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# File 'lib/sequel/adapters/shared/postgres.rb', line 362

def supports_savepoints?
  true
end

#supports_transaction_isolation_levels? ⇒ Boolean

PostgreSQL supports transaction isolation levels

Returns:

  • (Boolean) 


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# File 'lib/sequel/adapters/shared/postgres.rb', line 367

def supports_transaction_isolation_levels?
  true
end

#table_exists?(table, opts = {}) ⇒ Boolean

Whether the given table exists in the database

Options:

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

  • :server - The server to use

Returns:

  • (Boolean) 


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# File 'lib/sequel/adapters/shared/postgres.rb', line 376

def table_exists?(table, opts={})
  im = input_identifier_meth
  schema, table = schema_and_table(table)
  opts[:schema] ||= schema
  tables(opts){|ds| !ds.first(:relname=>im.call(table)).nil?}
end

#tables(opts = {}) ⇒ Object

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



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# File 'lib/sequel/adapters/shared/postgres.rb', line 390

def tables(opts={})
  ds = metadata_dataset.from(:pg_class).filter(:relkind=>'r').select(:relname).exclude(SQL::StringExpression.like(:relname, SYSTEM_TABLE_REGEXP)).server(opts[:server]).join(:pg_namespace, :oid=>:relnamespace) 
  ds = filter_schema(ds, opts)
  m = output_identifier_meth
  block_given? ? yield(ds) : ds.map{|r| m.call(r[:relname])}
end