Class: ActiveRecord::ConnectionAdapters::PostgreSQLAdapter

Inherits:
AbstractAdapter
  • Object
show all
Defined in:
lib/active_record/connection_adapters/postgresql_adapter.rb

Overview

The PostgreSQL adapter works both with the native C (ruby.scripting.ca/postgres/) and the pure Ruby (available both as gem and from rubyforge.org/frs/?group_id=234&release_id=1944) drivers.

Options:

  • :host - Defaults to “localhost”.

  • :port - Defaults to 5432.

  • :username - Defaults to nothing.

  • :password - Defaults to nothing.

  • :database - The name of the database. No default, must be provided.

  • :schema_search_path - An optional schema search path for the connection given as a string of comma-separated schema names. This is backward-compatible with the :schema_order option.

  • :encoding - An optional client encoding that is used in a SET client_encoding TO <encoding> call on the connection.

  • :min_messages - An optional client min messages that is used in a SET client_min_messages TO <min_messages> call on the connection.

  • :allow_concurrency - If true, use async query methods so Ruby threads don’t deadlock; otherwise, use blocking query methods.

Constant Summary collapse

ADAPTER_NAME = 
'PostgreSQL'.freeze
NATIVE_DATABASE_TYPES = 
{
  :primary_key => "serial primary key".freeze,
  :string      => { :name => "character varying", :limit => 255 },
  :text        => { :name => "text" },
  :integer     => { :name => "integer" },
  :float       => { :name => "float" },
  :decimal     => { :name => "decimal" },
  :datetime    => { :name => "timestamp" },
  :timestamp   => { :name => "timestamp" },
  :time        => { :name => "time" },
  :date        => { :name => "date" },
  :binary      => { :name => "bytea" },
  :boolean     => { :name => "boolean" },
  :xml         => { :name => "xml" }
}

Instance Attribute Summary

Attributes included from QueryCache

#query_cache, #query_cache_enabled

Instance Method Summary collapse

Methods inherited from AbstractAdapter

#current_savepoint_name, #decrement_open_transactions, #ids_in_list_limit, #increment_open_transactions, #open_transactions, #prefetch_primary_key?, #raw_connection, #requires_reloading?, #reset!, #supports_count_distinct?, #transaction_joinable=, #verify!

Methods included from QueryCache

#cache, #clear_query_cache, dirties_query_cache, included, #select_all, #uncached

Methods included from DatabaseLimits

#column_name_length, #columns_per_multicolumn_index, #columns_per_table, #in_clause_length, #indexes_per_table, #joins_per_query, #sql_query_length, #table_name_length

Methods included from Quoting

#quoted_false, #quoted_true

Methods included from DatabaseStatements

#add_limit_offset!, #add_transaction_record, #case_sensitive_equality_operator, #delete, #empty_insert_statement_value, #insert_fixture, #limited_update_conditions, #reset_sequence!, #sanitize_limit, #select_all, #select_one, #select_value, #select_values, #transaction, #update

Methods included from SchemaStatements

#add_column_options!, #add_index, #add_timestamps, #assume_migrated_upto_version, #change_table, #column_exists?, #create_table, #drop_table, #dump_schema_information, #index_exists?, #index_name, #index_name_exists?, #initialize_schema_migrations_table, #remove_column, #remove_index, #remove_timestamps, #rename_index, #structure_dump, #table_alias_for

Constructor Details

#initialize(connection, logger, connection_parameters, config) ⇒ PostgreSQLAdapter

Initializes and connects a PostgreSQL adapter.



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# File 'lib/active_record/connection_adapters/postgresql_adapter.rb', line 237

def initialize(connection, logger, connection_parameters, config)
  super(connection, logger)
  @connection_parameters, @config = connection_parameters, config

  # @local_tz is initialized as nil to avoid warnings when connect tries to use it
  @local_tz = nil
  @table_alias_length = nil
  @postgresql_version = nil

  connect
  @local_tz = execute('SHOW TIME ZONE').first["TimeZone"]
end

Instance Method Details

#active? ⇒ Boolean

Is this connection alive and ready for queries?

Returns:

  • (Boolean) 


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# File 'lib/active_record/connection_adapters/postgresql_adapter.rb', line 251

def active?
  if @connection.respond_to?(:status)
    @connection.status == PGconn::CONNECTION_OK
  else
    # We're asking the driver, not Active Record, so use @connection.query instead of #query
    @connection.query 'SELECT 1'
    true
  end
# postgres-pr raises a NoMethodError when querying if no connection is available.
rescue PGError, NoMethodError
  false
end

#adapter_name ⇒ Object

Returns ‘PostgreSQL’ as adapter name for identification purposes.



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# File 'lib/active_record/connection_adapters/postgresql_adapter.rb', line 232

def adapter_name
  ADAPTER_NAME
end

#add_column(table_name, column_name, type, options = {}) ⇒ Object

Adds a new column to the named table. See TableDefinition#column for details of the options you can use.



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# File 'lib/active_record/connection_adapters/postgresql_adapter.rb', line 813

def add_column(table_name, column_name, type, options = {})
  default = options[:default]
  notnull = options[:null] == false

  # Add the column.
  execute("ALTER TABLE #{quote_table_name(table_name)} ADD COLUMN #{quote_column_name(column_name)} #{type_to_sql(type, options[:limit], options[:precision], options[:scale])}")

  change_column_default(table_name, column_name, default) if options_include_default?(options)
  change_column_null(table_name, column_name, false, default) if notnull
end

#begin_db_transaction ⇒ Object

Begins a transaction.



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# File 'lib/active_record/connection_adapters/postgresql_adapter.rb', line 529

def begin_db_transaction
  execute "BEGIN"
end

#change_column(table_name, column_name, type, options = {}) ⇒ Object

Changes the column of a table.



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# File 'lib/active_record/connection_adapters/postgresql_adapter.rb', line 825

def change_column(table_name, column_name, type, options = {})
  quoted_table_name = quote_table_name(table_name)

  begin
    execute "ALTER TABLE #{quoted_table_name} ALTER COLUMN #{quote_column_name(column_name)} TYPE #{type_to_sql(type, options[:limit], options[:precision], options[:scale])}"
  rescue ActiveRecord::StatementInvalid => e
    raise e if postgresql_version > 80000
    # This is PostgreSQL 7.x, so we have to use a more arcane way of doing it.
    begin
      begin_db_transaction
      tmp_column_name = "#{column_name}_ar_tmp"
      add_column(table_name, tmp_column_name, type, options)
      execute "UPDATE #{quoted_table_name} SET #{quote_column_name(tmp_column_name)} = CAST(#{quote_column_name(column_name)} AS #{type_to_sql(type, options[:limit], options[:precision], options[:scale])})"
      remove_column(table_name, column_name)
      rename_column(table_name, tmp_column_name, column_name)
      commit_db_transaction
    rescue
      rollback_db_transaction
    end
  end

  change_column_default(table_name, column_name, options[:default]) if options_include_default?(options)
  change_column_null(table_name, column_name, options[:null], options[:default]) if options.key?(:null)
end

#change_column_default(table_name, column_name, default) ⇒ Object

Changes the default value of a table column.



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# File 'lib/active_record/connection_adapters/postgresql_adapter.rb', line 851

def change_column_default(table_name, column_name, default)
  execute "ALTER TABLE #{quote_table_name(table_name)} ALTER COLUMN #{quote_column_name(column_name)} SET DEFAULT #{quote(default)}"
end

#change_column_null(table_name, column_name, null, default = nil) ⇒ Object 



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# File 'lib/active_record/connection_adapters/postgresql_adapter.rb', line 855

def change_column_null(table_name, column_name, null, default = nil)
  unless null || default.nil?
    execute("UPDATE #{quote_table_name(table_name)} SET #{quote_column_name(column_name)}=#{quote(default)} WHERE #{quote_column_name(column_name)} IS NULL")
  end
  execute("ALTER TABLE #{quote_table_name(table_name)} ALTER #{quote_column_name(column_name)} #{null ? 'DROP' : 'SET'} NOT NULL")
end

#client_min_messages ⇒ Object

Returns the current client message level.



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# File 'lib/active_record/connection_adapters/postgresql_adapter.rb', line 716

def client_min_messages
  query('SHOW client_min_messages')[0][0]
end

#client_min_messages=(level) ⇒ Object

Set the client message level.



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# File 'lib/active_record/connection_adapters/postgresql_adapter.rb', line 721

def client_min_messages=(level)
  execute("SET client_min_messages TO '#{level}'")
end

#columns(table_name, name = nil) ⇒ Object

Returns the list of all column definitions for a table.



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# File 'lib/active_record/connection_adapters/postgresql_adapter.rb', line 678

def columns(table_name, name = nil)
  # Limit, precision, and scale are all handled by the superclass.
  column_definitions(table_name).collect do |name, type, default, notnull|
    PostgreSQLColumn.new(name, default, type, notnull == 'f')
  end
end

#commit_db_transaction ⇒ Object

Commits a transaction.



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# File 'lib/active_record/connection_adapters/postgresql_adapter.rb', line 534

def commit_db_transaction
  execute "COMMIT"
end

#create_database(name, options = {}) ⇒ Object

Create a new PostgreSQL database. Options include :owner, :template, :encoding, :tablespace, and :connection_limit (note that MySQL uses :charset while PostgreSQL uses :encoding).

Example:

create_database config[:database], config
create_database 'foo_development', :encoding => 'unicode'



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# File 'lib/active_record/connection_adapters/postgresql_adapter.rb', line 573

def create_database(name, options = {})
  options = options.reverse_merge(:encoding => "utf8")

  option_string = options.symbolize_keys.sum do |key, value|
    case key
    when :owner
      " OWNER = \"#{value}\""
    when :template
      " TEMPLATE = \"#{value}\""
    when :encoding
      " ENCODING = '#{value}'"
    when :tablespace
      " TABLESPACE = \"#{value}\""
    when :connection_limit
      " CONNECTION LIMIT = #{value}"
    else
      ""
    end
  end

  execute "CREATE DATABASE #{quote_table_name(name)}#{option_string}"
end

#create_savepoint ⇒ Object 



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# File 'lib/active_record/connection_adapters/postgresql_adapter.rb', line 547

def create_savepoint
  execute("SAVEPOINT #{current_savepoint_name}")
end

#current_database ⇒ Object

Returns the current database name.



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# File 'lib/active_record/connection_adapters/postgresql_adapter.rb', line 686

def current_database
  query('select current_database()')[0][0]
end

#default_sequence_name(table_name, pk = nil) ⇒ Object

Returns the sequence name for a table’s primary key or some other specified key.



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# File 'lib/active_record/connection_adapters/postgresql_adapter.rb', line 726

def default_sequence_name(table_name, pk = nil) #:nodoc:
  default_pk, default_seq = pk_and_sequence_for(table_name)
  default_seq || "#{table_name}_#{pk || default_pk || 'id'}_seq"
end

#disable_referential_integrity ⇒ Object

:nodoc:



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# File 'lib/active_record/connection_adapters/postgresql_adapter.rb', line 405

def disable_referential_integrity #:nodoc:
  if supports_disable_referential_integrity?() then
    execute(tables.collect { |name| "ALTER TABLE #{quote_table_name(name)} DISABLE TRIGGER ALL" }.join(";"))
  end
  yield
ensure
  if supports_disable_referential_integrity?() then
    execute(tables.collect { |name| "ALTER TABLE #{quote_table_name(name)} ENABLE TRIGGER ALL" }.join(";"))
  end
end

#disconnect! ⇒ Object

Close the connection.



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# File 'lib/active_record/connection_adapters/postgresql_adapter.rb', line 276

def disconnect!
  @connection.close rescue nil
end

#distinct(columns, order_by) ⇒ Object

Returns a SELECT DISTINCT clause for a given set of columns and a given ORDER BY clause.

PostgreSQL requires the ORDER BY columns in the select list for distinct queries, and requires that the ORDER BY include the distinct column.

distinct("posts.id", "posts.created_at desc")



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# File 'lib/active_record/connection_adapters/postgresql_adapter.rb', line 894

def distinct(columns, order_by) #:nodoc:
  return "DISTINCT #{columns}" if order_by.blank?

  # Construct a clean list of column names from the ORDER BY clause, removing
  # any ASC/DESC modifiers
  order_columns = order_by.split(',').collect { |s| s.split.first }
  order_columns.delete_if { |c| c.blank? }
  order_columns = order_columns.zip((0...order_columns.size).to_a).map { |s,i| "#{s} AS alias_#{i}" }

  # Return a DISTINCT ON() clause that's distinct on the columns we want but includes
  # all the required columns for the ORDER BY to work properly.
  sql = "DISTINCT ON (#{columns}) #{columns}, "
  sql << order_columns * ', '
end

#drop_database(name) ⇒ Object

Drops a PostgreSQL database

Example:

drop_database 'matt_development'



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# File 'lib/active_record/connection_adapters/postgresql_adapter.rb', line 600

def drop_database(name) #:nodoc:
  if postgresql_version >= 80200
    execute "DROP DATABASE IF EXISTS #{quote_table_name(name)}"
  else
    begin
      execute "DROP DATABASE #{quote_table_name(name)}"
    rescue ActiveRecord::StatementInvalid
      @logger.warn "#{name} database doesn't exist." if @logger
    end
  end
end

#encoding ⇒ Object

Returns the current database encoding format.



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# File 'lib/active_record/connection_adapters/postgresql_adapter.rb', line 691

def encoding
  query(<<-end_sql)[0][0]
    SELECT pg_encoding_to_char(pg_database.encoding) FROM pg_database
    WHERE pg_database.datname LIKE '#{current_database}'
  end_sql
end

#escape_bytea(value) ⇒ Object

Escapes binary strings for bytea input to the database.



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# File 'lib/active_record/connection_adapters/postgresql_adapter.rb', line 323

def escape_bytea(value)
  @connection.escape_bytea(value) if value
end

#execute(sql, name = nil) ⇒ Object

Executes an SQL statement, returning a PGresult object on success or raising a PGError exception otherwise.



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# File 'lib/active_record/connection_adapters/postgresql_adapter.rb', line 513

def execute(sql, name = nil)
  log(sql, name) do
    if @async
      @connection.async_exec(sql)
    else
      @connection.exec(sql)
    end
  end
end

#index_name_length ⇒ Object 



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# File 'lib/active_record/connection_adapters/postgresql_adapter.rb', line 871

def index_name_length
  63
end

#indexes(table_name, name = nil) ⇒ Object

Returns the list of all indexes for a table.



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# File 'lib/active_record/connection_adapters/postgresql_adapter.rb', line 644

def indexes(table_name, name = nil)
   schemas = schema_search_path.split(/,/).map { |p| quote(p) }.join(',')
   result = query(<<-SQL, name)
     SELECT distinct i.relname, d.indisunique, d.indkey, t.oid
       FROM pg_class t, pg_class i, pg_index d
     WHERE i.relkind = 'i'
       AND d.indexrelid = i.oid
       AND d.indisprimary = 'f'
       AND t.oid = d.indrelid
       AND t.relname = '#{table_name}'
       AND i.relnamespace IN (SELECT oid FROM pg_namespace WHERE nspname IN (#{schemas}) )
    ORDER BY i.relname
  SQL


  result.map do |row|
    index_name = row[0]
    unique = row[1] == 't'
    indkey = row[2].split(" ")
    oid = row[3]

    columns = Hash[query(<<-SQL, "Columns for index #{row[0]} on #{table_name}")]
    SELECT a.attnum, a.attname
    FROM pg_attribute a
    WHERE a.attrelid = #{oid}
    AND a.attnum IN (#{indkey.join(",")})
    SQL

    column_names = columns.values_at(*indkey).compact
    column_names.empty? ? nil : IndexDefinition.new(table_name, index_name, unique, column_names)
  end.compact
end

#insert(sql, name = nil, pk = nil, id_value = nil, sequence_name = nil) ⇒ Object Also known as: create

Executes an INSERT query and returns the new record’s ID



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# File 'lib/active_record/connection_adapters/postgresql_adapter.rb', line 425

def insert(sql, name = nil, pk = nil, id_value = nil, sequence_name = nil)
  # Extract the table from the insert sql. Yuck.
  table = sql.split(" ", 4)[2].gsub('"', '')

  # Try an insert with 'returning id' if available (PG >= 8.2)
  if supports_insert_with_returning?
    pk, sequence_name = *pk_and_sequence_for(table) unless pk
    if pk
      id = select_value("#{sql} RETURNING #{quote_column_name(pk)}")
      clear_query_cache
      return id
    end
  end

  # Otherwise, insert then grab last_insert_id.
  if insert_id = super
    insert_id
  else
    # If neither pk nor sequence name is given, look them up.
    unless pk || sequence_name
      pk, sequence_name = *pk_and_sequence_for(table)
    end

    # If a pk is given, fallback to default sequence name.
    # Don't fetch last insert id for a table without a pk.
    if pk && sequence_name ||= default_sequence_name(table, pk)
      last_insert_id(table, sequence_name)
    end
  end
end

#native_database_types ⇒ Object

:nodoc:



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# File 'lib/active_record/connection_adapters/postgresql_adapter.rb', line 280

def native_database_types #:nodoc:
  NATIVE_DATABASE_TYPES
end

#outside_transaction? ⇒ Boolean

Returns:

  • (Boolean) 


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# File 'lib/active_record/connection_adapters/postgresql_adapter.rb', line 543

def outside_transaction?
  @connection.transaction_status == PGconn::PQTRANS_IDLE
end

#pk_and_sequence_for(table) ⇒ Object

Returns a table’s primary key and belonging sequence.



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# File 'lib/active_record/connection_adapters/postgresql_adapter.rb', line 752

def pk_and_sequence_for(table) #:nodoc:
  # First try looking for a sequence with a dependency on the
  # given table's primary key.
  result = query(<<-end_sql, 'PK and serial sequence')[0]
    SELECT attr.attname, seq.relname
    FROM pg_class      seq,
         pg_attribute  attr,
         pg_depend     dep,
         pg_namespace  name,
         pg_constraint cons
    WHERE seq.oid           = dep.objid
      AND seq.relkind       = 'S'
      AND attr.attrelid     = dep.refobjid
      AND attr.attnum       = dep.refobjsubid
      AND attr.attrelid     = cons.conrelid
      AND attr.attnum       = cons.conkey[1]
      AND cons.contype      = 'p'
      AND dep.refobjid      = '#{quote_table_name(table)}'::regclass
  end_sql

  if result.nil? or result.empty?
    # If that fails, try parsing the primary key's default value.
    # Support the 7.x and 8.0 nextval('foo'::text) as well as
    # the 8.1+ nextval('foo'::regclass).
    result = query(<<-end_sql, 'PK and custom sequence')[0]
      SELECT attr.attname,
        CASE
          WHEN split_part(def.adsrc, '''', 2) ~ '.' THEN
            substr(split_part(def.adsrc, '''', 2),
                   strpos(split_part(def.adsrc, '''', 2), '.')+1)
          ELSE split_part(def.adsrc, '''', 2)
        END
      FROM pg_class       t
      JOIN pg_attribute   attr ON (t.oid = attrelid)
      JOIN pg_attrdef     def  ON (adrelid = attrelid AND adnum = attnum)
      JOIN pg_constraint  cons ON (conrelid = adrelid AND adnum = conkey[1])
      WHERE t.oid = '#{quote_table_name(table)}'::regclass
        AND cons.contype = 'p'
        AND def.adsrc ~* 'nextval'
    end_sql
  end

  # [primary_key, sequence]
  [result.first, result.last]
rescue
  nil
end

#primary_key(table) ⇒ Object

Returns just a table’s primary key



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# File 'lib/active_record/connection_adapters/postgresql_adapter.rb', line 801

def primary_key(table)
  pk_and_sequence = pk_and_sequence_for(table)
  pk_and_sequence && pk_and_sequence.first
end

#query(sql, name = nil) ⇒ Object

Queries the database and returns the results in an Array-like object



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# File 'lib/active_record/connection_adapters/postgresql_adapter.rb', line 500

def query(sql, name = nil) #:nodoc:
  log(sql, name) do
    if @async
      res = @connection.async_exec(sql)
    else
      res = @connection.exec(sql)
    end
    return result_as_array(res)
  end
end

#quote(value, column = nil) ⇒ Object

Quotes PostgreSQL-specific data types for SQL input.



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# File 'lib/active_record/connection_adapters/postgresql_adapter.rb', line 335

def quote(value, column = nil) #:nodoc:
  return super unless column

  if value.kind_of?(String) && column.type == :binary
    "'#{escape_bytea(value)}'"
  elsif Float === value && column.type == :datetime
    return super unless value.infinite?
    "'#{value.to_s.downcase}'"
  elsif value.kind_of?(String) && column.sql_type == 'xml'
    "xml '#{quote_string(value)}'"
  elsif value.kind_of?(Numeric) && column.sql_type == 'money'
    # Not truly string input, so doesn't require (or allow) escape string syntax.
    "'#{value}'"
  elsif value.kind_of?(String) && column.sql_type =~ /^bit/
    case value
      when /^[01]*$/
        "B'#{value}'" # Bit-string notation
      when /^[0-9A-F]*$/i
        "X'#{value}'" # Hexadecimal notation
    end
  else
    super
  end
end

#quote_column_name(name) ⇒ Object

Quotes column names for use in SQL queries.



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# File 'lib/active_record/connection_adapters/postgresql_adapter.rb', line 385

def quote_column_name(name) #:nodoc:
  PGconn.quote_ident(name.to_s)
end

#quote_string(s) ⇒ Object

Quotes strings for use in SQL input.



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# File 'lib/active_record/connection_adapters/postgresql_adapter.rb', line 361

def quote_string(s) #:nodoc:
  @connection.escape(s)
end

#quote_table_name(name) ⇒ Object

Checks the following cases:

  • table_name

  • “table.name”

  • schema_name.table_name

  • schema_name.“table.name”

  • “schema.name”.table_name

  • “schema.name”.“table.name”



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# File 'lib/active_record/connection_adapters/postgresql_adapter.rb', line 373

def quote_table_name(name)
  schema, name_part = extract_pg_identifier_from_name(name.to_s)

  unless name_part
    quote_column_name(schema)
  else
    table_name, name_part = extract_pg_identifier_from_name(name_part)
    "#{quote_column_name(schema)}.#{quote_column_name(table_name)}"
  end
end

#quoted_date(value) ⇒ Object

Quote date/time values for use in SQL input. Includes microseconds if the value is a Time responding to usec.



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# File 'lib/active_record/connection_adapters/postgresql_adapter.rb', line 391

def quoted_date(value) #:nodoc:
  if value.acts_like?(:time) && value.respond_to?(:usec)
    "#{super}.#{sprintf("%06d", value.usec)}"
  else
    super
  end
end

#reconnect! ⇒ Object

Close then reopen the connection.



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# File 'lib/active_record/connection_adapters/postgresql_adapter.rb', line 265

def reconnect!
  if @connection.respond_to?(:reset)
    @connection.reset
    configure_connection
  else
    disconnect!
    connect
  end
end

#recreate_database(name) ⇒ Object

SCHEMA STATEMENTS ========================================



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# File 'lib/active_record/connection_adapters/postgresql_adapter.rb', line 561

def recreate_database(name) #:nodoc:
  drop_database(name)
  create_database(name)
end

#release_savepoint ⇒ Object 



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# File 'lib/active_record/connection_adapters/postgresql_adapter.rb', line 555

def release_savepoint
  execute("RELEASE SAVEPOINT #{current_savepoint_name}")
end

#remove_index!(table_name, index_name) ⇒ Object

:nodoc:



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# File 'lib/active_record/connection_adapters/postgresql_adapter.rb', line 867

def remove_index!(table_name, index_name) #:nodoc:
  execute "DROP INDEX #{quote_table_name(index_name)}"
end

#rename_column(table_name, column_name, new_column_name) ⇒ Object

Renames a column in a table.



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# File 'lib/active_record/connection_adapters/postgresql_adapter.rb', line 863

def rename_column(table_name, column_name, new_column_name)
  execute "ALTER TABLE #{quote_table_name(table_name)} RENAME COLUMN #{quote_column_name(column_name)} TO #{quote_column_name(new_column_name)}"
end

#rename_table(name, new_name) ⇒ Object

Renames a table.



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# File 'lib/active_record/connection_adapters/postgresql_adapter.rb', line 807

def rename_table(name, new_name)
  execute "ALTER TABLE #{quote_table_name(name)} RENAME TO #{quote_table_name(new_name)}"
end

#reset_pk_sequence!(table, pk = nil, sequence = nil) ⇒ Object

Resets the sequence of a table’s primary key to the maximum value.



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# File 'lib/active_record/connection_adapters/postgresql_adapter.rb', line 732

def reset_pk_sequence!(table, pk = nil, sequence = nil) #:nodoc:
  unless pk and sequence
    default_pk, default_sequence = pk_and_sequence_for(table)
    pk ||= default_pk
    sequence ||= default_sequence
  end
  if pk
    if sequence
      quoted_sequence = quote_column_name(sequence)

      select_value <<-end_sql, 'Reset sequence'
        SELECT setval('#{quoted_sequence}', (SELECT COALESCE(MAX(#{quote_column_name pk})+(SELECT increment_by FROM #{quoted_sequence}), (SELECT min_value FROM #{quoted_sequence})) FROM #{quote_table_name(table)}), false)
      end_sql
    else
      @logger.warn "#{table} has primary key #{pk} with no default sequence" if @logger
    end
  end
end

#result_as_array(res) ⇒ Object

create a 2D array representing the result set



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# File 'lib/active_record/connection_adapters/postgresql_adapter.rb', line 458

def result_as_array(res) #:nodoc:
  # check if we have any binary column and if they need escaping
  unescape_col = []
  res.nfields.times do |j|
    unescape_col << res.ftype(j)
  end

  ary = []
  res.ntuples.times do |i|
    ary << []
    res.nfields.times do |j|
      data = res.getvalue(i,j)
      case unescape_col[j]

      # unescape string passed BYTEA field (OID == 17)
      when BYTEA_COLUMN_TYPE_OID
        data = unescape_bytea(data) if String === data

      # If this is a money type column and there are any currency symbols,
      # then strip them off. Indeed it would be prettier to do this in
      # PostgreSQLColumn.string_to_decimal but would break form input
      # fields that call value_before_type_cast.
      when MONEY_COLUMN_TYPE_OID
        # Because money output is formatted according to the locale, there are two
        # cases to consider (note the decimal separators):
        #  (1) $12,345,678.12
        #  (2) $12.345.678,12
        case data
        when /^-?\D+[\d,]+\.\d{2}$/  # (1)
          data.gsub!(/[^-\d\.]/, '')
        when /^-?\D+[\d\.]+,\d{2}$/  # (2)
          data.gsub!(/[^-\d,]/, '').sub!(/,/, '.')
        end
      end
      ary[i] << data
    end
  end
  return ary
end

#rollback_db_transaction ⇒ Object

Aborts a transaction.



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# File 'lib/active_record/connection_adapters/postgresql_adapter.rb', line 539

def rollback_db_transaction
  execute "ROLLBACK"
end

#rollback_to_savepoint ⇒ Object 



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# File 'lib/active_record/connection_adapters/postgresql_adapter.rb', line 551

def rollback_to_savepoint
  execute("ROLLBACK TO SAVEPOINT #{current_savepoint_name}")
end

#schema_search_path ⇒ Object

Returns the active schema search path.



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# File 'lib/active_record/connection_adapters/postgresql_adapter.rb', line 711

def schema_search_path
  @schema_search_path ||= query('SHOW search_path')[0][0]
end

#schema_search_path=(schema_csv) ⇒ Object

Sets the schema search path to a string of comma-separated schema names. Names beginning with $ have to be quoted (e.g. $user => ‘$user’). See: www.postgresql.org/docs/current/static/ddl-schemas.html

This should be not be called manually but set in database.yml.



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# File 'lib/active_record/connection_adapters/postgresql_adapter.rb', line 703

def schema_search_path=(schema_csv)
  if schema_csv
    execute "SET search_path TO #{schema_csv}"
    @schema_search_path = schema_csv
  end
end

#select_rows(sql, name = nil) ⇒ Object

Executes a SELECT query and returns an array of rows. Each row is an array of field values.



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# File 'lib/active_record/connection_adapters/postgresql_adapter.rb', line 420

def select_rows(sql, name = nil)
  select_raw(sql, name).last
end

#set_standard_conforming_strings ⇒ Object

Enable standard-conforming strings if available.



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# File 'lib/active_record/connection_adapters/postgresql_adapter.rb', line 295

def set_standard_conforming_strings
  old, self.client_min_messages = client_min_messages, 'panic'
  execute('SET standard_conforming_strings = on') rescue nil
ensure
  self.client_min_messages = old
end

#supports_ddl_transactions? ⇒ Boolean

Returns:

  • (Boolean) 


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# File 'lib/active_record/connection_adapters/postgresql_adapter.rb', line 306

def supports_ddl_transactions?
  true
end

#supports_disable_referential_integrity? ⇒ Boolean

REFERENTIAL INTEGRITY ====================================

Returns:

  • (Boolean) 


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# File 'lib/active_record/connection_adapters/postgresql_adapter.rb', line 401

def supports_disable_referential_integrity?() #:nodoc:
  postgresql_version >= 80100
end

#supports_insert_with_returning? ⇒ Boolean

Returns:

  • (Boolean) 


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# File 'lib/active_record/connection_adapters/postgresql_adapter.rb', line 302

def supports_insert_with_returning?
  postgresql_version >= 80200
end

#supports_migrations? ⇒ Boolean

Does PostgreSQL support migrations?

Returns:

  • (Boolean) 


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# File 'lib/active_record/connection_adapters/postgresql_adapter.rb', line 285

def supports_migrations?
  true
end

#supports_primary_key? ⇒ Boolean

Does PostgreSQL support finding primary key on non-Active Record tables?

Returns:

  • (Boolean) 


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# File 'lib/active_record/connection_adapters/postgresql_adapter.rb', line 290

def supports_primary_key? #:nodoc:
  true
end

#supports_savepoints? ⇒ Boolean

Returns:

  • (Boolean) 


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# File 'lib/active_record/connection_adapters/postgresql_adapter.rb', line 310

def supports_savepoints?
  true
end

#table_alias_length ⇒ Object

Returns the configured supported identifier length supported by PostgreSQL, or report the default of 63 on PostgreSQL 7.x.



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# File 'lib/active_record/connection_adapters/postgresql_adapter.rb', line 316

def table_alias_length
  @table_alias_length ||= (postgresql_version >= 80000 ? query('SHOW max_identifier_length')[0][0].to_i : 63)
end

#table_exists?(name) ⇒ Boolean

Returns:

  • (Boolean) 


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# File 'lib/active_record/connection_adapters/postgresql_adapter.rb', line 621

def table_exists?(name)
  name          = name.to_s
  schema, table = name.split('.', 2)

  unless table # A table was provided without a schema
    table  = schema
    schema = nil
  end

  if name =~ /^"/ # Handle quoted table names
    table  = name
    schema = nil
  end

  query(<<-SQL).first[0].to_i > 0
      SELECT COUNT(*)
      FROM pg_tables
      WHERE tablename = '#{table.gsub(/(^"|"$)/,'')}'
      #{schema ? "AND schemaname = '#{schema}'" : ''}
  SQL
end

#tables(name = nil) ⇒ Object

Returns the list of all tables in the schema search path or a specified schema.



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# File 'lib/active_record/connection_adapters/postgresql_adapter.rb', line 613

def tables(name = nil)
  query(<<-SQL, name).map { |row| row[0] }
    SELECT tablename
    FROM pg_tables
    WHERE schemaname = ANY (current_schemas(false))
  SQL
end

#type_to_sql(type, limit = nil, precision = nil, scale = nil) ⇒ Object

Maps logical Rails types to PostgreSQL-specific data types.



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# File 'lib/active_record/connection_adapters/postgresql_adapter.rb', line 876

def type_to_sql(type, limit = nil, precision = nil, scale = nil)
  return super unless type.to_s == 'integer'
  return 'integer' unless limit

  case limit
    when 1, 2; 'smallint'
    when 3, 4; 'integer'
    when 5..8; 'bigint'
    else raise(ActiveRecordError, "No integer type has byte size #{limit}. Use a numeric with precision 0 instead.")
  end
end

#unescape_bytea(value) ⇒ Object

Unescapes bytea output from a database to the binary string it represents. NOTE: This is NOT an inverse of escape_bytea! This is only to be used

on escaped binary output from database drive.



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# File 'lib/active_record/connection_adapters/postgresql_adapter.rb', line 330

def unescape_bytea(value)
  @connection.unescape_bytea(value) if value
end

#update_sql(sql, name = nil) ⇒ Object

Executes an UPDATE query and returns the number of affected tuples.



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# File 'lib/active_record/connection_adapters/postgresql_adapter.rb', line 524

def update_sql(sql, name = nil)
  super.cmd_tuples
end