Class: Sequel::Database

Inherits:
Object show all
Extended by:
Metaprogramming
Includes:
Metaprogramming
Defined in:
lib/sequel/database.rb,
lib/sequel/database/misc.rb,
lib/sequel/database/query.rb,
lib/sequel/database/dataset.rb,
lib/sequel/database/logging.rb,
lib/sequel/extensions/query.rb,
lib/sequel/database/connecting.rb,
lib/sequel/database/schema_methods.rb,
lib/sequel/extensions/schema_dumper.rb,
lib/sequel/database/dataset_defaults.rb,
lib/sequel/extensions/schema_caching.rb

Overview

A Database object represents a virtual connection to a database. The Database class is meant to be subclassed by database adapters in order to provide the functionality needed for executing queries.

Constant Summary collapse

SQL_BEGIN =

:section: 1 - Methods that execute queries and/or return results This methods generally execute SQL code on the database server.

'BEGIN'.freeze
SQL_COMMIT = 
'COMMIT'.freeze
SQL_RELEASE_SAVEPOINT = 
'RELEASE SAVEPOINT autopoint_%d'.freeze
SQL_ROLLBACK = 
'ROLLBACK'.freeze
SQL_ROLLBACK_TO_SAVEPOINT = 
'ROLLBACK TO SAVEPOINT autopoint_%d'.freeze
SQL_SAVEPOINT = 
'SAVEPOINT autopoint_%d'.freeze
TRANSACTION_BEGIN = 
'Transaction.begin'.freeze
TRANSACTION_COMMIT = 
'Transaction.commit'.freeze
TRANSACTION_ROLLBACK = 
'Transaction.rollback'.freeze
TRANSACTION_ISOLATION_LEVELS = 
{:uncommitted=>'READ UNCOMMITTED'.freeze,
:committed=>'READ COMMITTED'.freeze,
:repeatable=>'REPEATABLE READ'.freeze,
:serializable=>'SERIALIZABLE'.freeze}
POSTGRES_DEFAULT_RE = 
/\A(?:B?('.*')::[^']+|\((-?\d+(?:\.\d+)?)\))\z/
MSSQL_DEFAULT_RE = 
/\A(?:\(N?('.*')\)|\(\((-?\d+(?:\.\d+)?)\)\))\z/
MYSQL_TIMESTAMP_RE = 
/\ACURRENT_(?:DATE|TIMESTAMP)?\z/
STRING_DEFAULT_RE = 
/\A'(.*)'\z/
ADAPTERS =

Array of supported database adapters

%w'ado amalgalite db2 dbi do firebird ibmdb informix jdbc mock mysql mysql2 odbc openbase oracle postgres sqlite swift tinytds'.collect{|x| x.to_sym}
AUTOINCREMENT =

:section: 2 - Methods that modify the database schema These methods execute code on the database that modifies the database’s schema.

'AUTOINCREMENT'.freeze
COMMA_SEPARATOR = 
', '.freeze
NOT_NULL = 
' NOT NULL'.freeze
NULL = 
' NULL'.freeze
PRIMARY_KEY = 
' PRIMARY KEY'.freeze
TEMPORARY = 
'TEMPORARY '.freeze
UNDERSCORE = 
'_'.freeze
UNIQUE = 
' UNIQUE'.freeze
UNSIGNED = 
' UNSIGNED'.freeze
COLUMN_DEFINITION_ORDER =

The order of column modifiers to use when defining a column.

[:collate, :default, :null, :unique, :primary_key, :auto_increment, :references]
DEFAULT_JOIN_TABLE_COLUMN_OPTIONS =

The default options for join table columns.

{:null=>false}
DatasetClass =

The default class to use for datasets

Sequel::Dataset
@@single_threaded =

Whether to use the single threaded connection pool by default

false
@@identifier_input_method =

The identifier input method to use by default

nil
@@identifier_output_method =

The identifier output method to use by default

nil
@@quote_identifiers =

Whether to quote identifiers (columns and tables) by default

nil

Instance Attribute Summary collapse

Class Method Summary collapse

Instance Method Summary collapse

Methods included from Metaprogramming

meta_def

Constructor Details

#initialize(opts = {}, &block) ⇒ Database

Constructs a new instance of a database connection with the specified options hash.

Accepts the following options:

:default_schema

The default schema to use, see #default_schema.

:disconnection_proc

A proc used to disconnect the connection

:identifier_input_method

A string method symbol to call on identifiers going into the database

:identifier_output_method

A string method symbol to call on identifiers coming from the database

:logger

A specific logger to use

:loggers

An array of loggers to use

:quote_identifiers

Whether to quote identifiers

:servers

A hash specifying a server/shard specific options, keyed by shard symbol

:single_threaded

Whether to use a single-threaded connection pool

:sql_log_level

Method to use to log SQL to a logger, :info by default.

All options given are also passed to the connection pool. If a block is given, it is used as the connection_proc for the ConnectionPool.



42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
 
# File 'lib/sequel/database/misc.rb', line 42

def initialize(opts = {}, &block)
  @opts ||= opts
  @opts = connection_pool_default_options.merge(@opts)
  @loggers = Array(@opts[:logger]) + Array(@opts[:loggers])
  self.log_warn_duration = @opts[:log_warn_duration]
  @opts[:disconnection_proc] ||= proc{|conn| disconnect_connection(conn)}
  block ||= proc{|server| connect(server)}
  @opts[:servers] = {} if @opts[:servers].is_a?(String)
  @opts[:adapter_class] = self.class
  
  @opts[:single_threaded] = @single_threaded = typecast_value_boolean(@opts.fetch(:single_threaded, @@single_threaded))
  @schemas = {}
  @default_schema = @opts.fetch(:default_schema, default_schema_default)
  @prepared_statements = {}
  @transactions = {}
  @identifier_input_method = nil
  @identifier_output_method = nil
  @quote_identifiers = nil
  @timezone = nil
  @dataset_class = dataset_class_default
  @cache_schema = typecast_value_boolean(@opts.fetch(:cache_schema, true))
  @dataset_modules = []
  self.sql_log_level = @opts[:sql_log_level] ? @opts[:sql_log_level].to_sym : :info
  @pool = ConnectionPool.get_pool(@opts, &block)

  Sequel.synchronize{::Sequel::DATABASES.push(self)}
end

Instance Attribute Details

#cache_schema ⇒ Object

Whether the schema should be cached for this database. True by default for performance, can be set to false to always issue a database query to get the schema.



42
43
44
 
# File 'lib/sequel/database/query.rb', line 42

def cache_schema
  @cache_schema
end

#dataset_class ⇒ Object

The class to use for creating datasets. Should respond to new with the Database argument as the first argument, and an optional options hash.



51
52
53
 
# File 'lib/sequel/database/dataset_defaults.rb', line 51

def dataset_class
  @dataset_class
end

#default_schema ⇒ Object

The default schema to use, generally should be nil. This sets the default schema used for some schema modification and introspection queries, but does not effect most dataset code.



56
57
58
 
# File 'lib/sequel/database/dataset_defaults.rb', line 56

def default_schema
  @default_schema
end

#log_warn_duration ⇒ Object

Numeric specifying the duration beyond which queries are logged at warn level instead of info level.



10
11
12
 
# File 'lib/sequel/database/logging.rb', line 10

def log_warn_duration
  @log_warn_duration
end

#loggers ⇒ Object

Array of SQL loggers to use for this database.



13
14
15
 
# File 'lib/sequel/database/logging.rb', line 13

def loggers
  @loggers
end

#opts ⇒ Object (readonly)

The options hash for this database



20
21
22
 
# File 'lib/sequel/database/misc.rb', line 20

def opts
  @opts
end

#pool ⇒ Object (readonly)

The connection pool for this Database instance. All Database instances have their own connection pools.



116
117
118
 
# File 'lib/sequel/database/connecting.rb', line 116

def pool
  @pool
end

#prepared_statements ⇒ Object (readonly)

The prepared statement object hash for this database, keyed by name symbol



30
31
32
 
# File 'lib/sequel/database/query.rb', line 30

def prepared_statements
  @prepared_statements
end

#sql_log_level ⇒ Object

Log level at which to log SQL queries. This is actually the method sent to the logger, so it should be the method name symbol. The default is :info, it can be set to :debug to log at DEBUG level.



18
19
20
 
# File 'lib/sequel/database/logging.rb', line 18

def sql_log_level
  @sql_log_level
end

#timezone ⇒ Object

The timezone to use for this database, defaulting to Sequel.database_timezone.



206
207
208
 
# File 'lib/sequel/database/misc.rb', line 206

def timezone
  @timezone || Sequel.database_timezone
end

#transaction_isolation_level ⇒ Object

The default transaction isolation level for this database, used for all future transactions. For MSSQL, this should be set to something if you ever plan to use the :isolation option to Database#transaction, as on MSSQL if affects all future transactions on the same connection.



37
38
39
 
# File 'lib/sequel/database/query.rb', line 37

def transaction_isolation_level
  @transaction_isolation_level
end

Class Method Details

.adapter_class(scheme) ⇒ Object

The Database subclass for the given adapter scheme. Raises Sequel::AdapterNotFound if the adapter could not be loaded.



17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
 
# File 'lib/sequel/database/connecting.rb', line 17

def self.adapter_class(scheme)
  return scheme if scheme.is_a?(Class)

  scheme = scheme.to_s.gsub('-', '_').to_sym
  
  unless klass = ADAPTER_MAP[scheme]
    # attempt to load the adapter file
    begin
      Sequel.tsk_require "sequel/adapters/#{scheme}"
    rescue LoadError => e
      raise Sequel.convert_exception_class(e, AdapterNotFound)
    end
    
    # make sure we actually loaded the adapter
    unless klass = ADAPTER_MAP[scheme]
      raise AdapterNotFound, "Could not load #{scheme} adapter: adapter class not registered in ADAPTER_MAP"
    end
  end
  klass
end

.adapter_scheme ⇒ Object

Returns the scheme symbol for the Database class.



39
40
41
 
# File 'lib/sequel/database/connecting.rb', line 39

def self.adapter_scheme
  @scheme
end

.connect(conn_string, opts = {}) ⇒ Object

Connects to a database. See Sequel.connect.



44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
 
# File 'lib/sequel/database/connecting.rb', line 44

def self.connect(conn_string, opts = {})
  case conn_string
  when String
    if match = /\A(jdbc|do):/o.match(conn_string)
      c = adapter_class(match[1].to_sym)
      opts = opts.merge(:orig_opts=>opts.dup)
      opts = {:uri=>conn_string}.merge(opts)
    else
      uri = URI.parse(conn_string)
      scheme = uri.scheme
      scheme = :dbi if scheme =~ /\Adbi-/
      c = adapter_class(scheme)
      uri_options = c.send(:uri_to_options, uri)
      uri.query.split('&').collect{|s| s.split('=')}.each{|k,v| uri_options[k.to_sym] = v if k && !k.empty?} unless uri.query.to_s.strip.empty?
      uri_options.to_a.each{|k,v| uri_options[k] = URI.unescape(v) if v.is_a?(String)}
      opts = opts.merge(:orig_opts=>opts.dup)
      opts[:uri] = conn_string
      opts = uri_options.merge(opts)
      opts[:adapter] = scheme
    end
  when Hash
    opts = conn_string.merge(opts)
    opts = opts.merge(:orig_opts=>opts.dup)
    c = adapter_class(opts[:adapter_class] || opts[:adapter] || opts['adapter'])
  else
    raise Error, "Sequel::Database.connect takes either a Hash or a String, given: #{conn_string.inspect}"
  end
  # process opts a bit
  opts = opts.inject({}) do |m, (k,v)|
    k = :user if k.to_s == 'username'
    m[k.to_sym] = v
    m
  end
  begin
    db = c.new(opts)
    db.test_connection if opts[:test] && db.send(:typecast_value_boolean, opts[:test])
    result = yield(db) if block_given?
  ensure
    if block_given?
      db.disconnect if db
      Sequel.synchronize{::Sequel::DATABASES.delete(db)}
    end
  end
  block_given? ? result : db
end

.identifier_input_method ⇒ Object

The method to call on identifiers going into the database



21
22
23
 
# File 'lib/sequel/database/dataset_defaults.rb', line 21

def self.identifier_input_method
  @@identifier_input_method
end

.identifier_input_method=(v) ⇒ Object

Set the method to call on identifiers going into the database See Sequel.identifier_input_method=.



27
28
29
 
# File 'lib/sequel/database/dataset_defaults.rb', line 27

def self.identifier_input_method=(v)
  @@identifier_input_method = v || ""
end

.identifier_output_method ⇒ Object

The method to call on identifiers coming from the database



32
33
34
 
# File 'lib/sequel/database/dataset_defaults.rb', line 32

def self.identifier_output_method
  @@identifier_output_method
end

.identifier_output_method=(v) ⇒ Object

Set the method to call on identifiers coming from the database See Sequel.identifier_output_method=.



38
39
40
 
# File 'lib/sequel/database/dataset_defaults.rb', line 38

def self.identifier_output_method=(v)
  @@identifier_output_method = v || ""
end

.quote_identifiers=(value) ⇒ Object

Sets the default quote_identifiers mode for new databases. See Sequel.quote_identifiers=.



44
45
46
 
# File 'lib/sequel/database/dataset_defaults.rb', line 44

def self.quote_identifiers=(value)
  @@quote_identifiers = value
end

.single_threaded=(value) ⇒ Object

Sets the default single_threaded mode for new databases. See Sequel.single_threaded=.



92
93
94
 
# File 'lib/sequel/database/connecting.rb', line 92

def self.single_threaded=(value)
  @@single_threaded = value
end

Instance Method Details

#<<(sql) ⇒ Object

Runs the supplied SQL statement string on the database server. Returns self so it can be safely chained:

DB << "UPDATE albums SET artist_id = NULL" << "DROP TABLE artists"



48
49
50
51
 
# File 'lib/sequel/database/query.rb', line 48

def <<(sql)
  run(sql)
  self
end

#[](*args) ⇒ Object

Returns a dataset for the database. If the first argument is a string, the method acts as an alias for Database#fetch, returning a dataset for arbitrary SQL, with or without placeholders:

DB['SELECT * FROM items'].all
DB['SELECT * FROM items WHERE name = ?', my_name].all

Otherwise, acts as an alias for Database#from, setting the primary table for the dataset:

DB[:items].sql #=> "SELECT * FROM items"



19
20
21
 
# File 'lib/sequel/database/dataset.rb', line 19

def [](*args)
  (String === args.first) ? fetch(*args) : from(*args)
end

#adapter_scheme ⇒ Object

Returns the scheme symbol for this instance’s class, which reflects which adapter is being used. In some cases, this can be the same as the database_type (for native adapters), in others (i.e. adapters with subadapters), it will be different.

Sequel.connect('jdbc:postgres://...').adapter_scheme # => :jdbc



124
125
126
 
# File 'lib/sequel/database/connecting.rb', line 124

def adapter_scheme
  self.class.adapter_scheme
end

#add_column(table, *args) ⇒ Object

Adds a column to the specified table. This method expects a column name, a datatype and optionally a hash with additional constraints and options:

DB.add_column :items, :name, :text, :unique => true, :null => false
DB.add_column :items, :category, :text, :default => 'ruby'

See alter_table.



31
32
33
 
# File 'lib/sequel/database/schema_methods.rb', line 31

def add_column(table, *args)
  alter_table(table) {add_column(*args)}
end

#add_index(table, columns, options = {}) ⇒ Object

Adds an index to a table for the given columns:

DB.add_index :posts, :title
DB.add_index :posts, [:author, :title], :unique => true

Options:

:ignore_errors

Ignore any DatabaseErrors that are raised

See alter_table.



44
45
46
47
48
49
50
51
 
# File 'lib/sequel/database/schema_methods.rb', line 44

def add_index(table, columns, options={})
  e = options[:ignore_errors]
  begin
    alter_table(table){add_index(columns, options)}
  rescue DatabaseError
    raise unless e
  end
end

#add_servers(servers) ⇒ Object

Dynamically add new servers or modify server options at runtime. Also adds new servers to the connection pool. Intended for use with master/slave or shard configurations where it is useful to add new server hosts at runtime.

servers argument should be a hash with server name symbol keys and hash or proc values. If a servers key is already in use, it’s value is overridden with the value provided.

DB.add_servers(:f=>{:host=>"hash_host_f"})



137
138
139
140
141
142
 
# File 'lib/sequel/database/connecting.rb', line 137

def add_servers(servers)
  if h = @opts[:servers]
    Sequel.synchronize{h.merge!(servers)}
    @pool.add_servers(servers.keys)
  end
end

#after_commit(opts = {}, &block) ⇒ Object

If a transaction is not currently in process, yield to the block immediately. Otherwise, add the block to the list of blocks to call after the currently in progress transaction commits (and only if it commits). Options:

:server

The server/shard to use.

Raises:



75
76
77
78
79
80
81
82
83
84
85
 
# File 'lib/sequel/database/misc.rb', line 75

def after_commit(opts={}, &block)
  raise Error, "must provide block to after_commit" unless block
  synchronize(opts[:server]) do |conn|
    if h = _trans(conn)
      raise Error, "cannot call after_commit in a prepared transaction" if h[:prepare]
      (h[:after_commit] ||= []) << block
    else
      yield
    end
  end
end

#after_rollback(opts = {}, &block) ⇒ Object

If a transaction is not currently in progress, ignore the block. Otherwise, add the block to the list of the blocks to call after the currently in progress transaction rolls back (and only if it rolls back). Options:

:server

The server/shard to use.

Raises:



92
93
94
95
96
97
98
99
100
 
# File 'lib/sequel/database/misc.rb', line 92

def after_rollback(opts={}, &block)
  raise Error, "must provide block to after_rollback" unless block
  synchronize(opts[:server]) do |conn|
    if h = _trans(conn)
      raise Error, "cannot call after_rollback in a prepared transaction" if h[:prepare]
      (h[:after_rollback] ||= []) << block
    end
  end
end

#alter_table(name, generator = nil, &block) ⇒ Object

Alters the given table with the specified block. Example:

DB.alter_table :items do
  add_column :category, :text, :default => 'ruby'
  drop_column :category
  rename_column :cntr, :counter
  set_column_type :value, :float
  set_column_default :value, :float
  add_index [:group, :category]
  drop_index [:group, :category]
end

Note that add_column accepts all the options available for column definitions using create_table, and add_index accepts all the options available for index definition.

See Schema::AlterTableGenerator and the “Migrations and Schema Modification” guide.



70
71
72
73
74
75
 
# File 'lib/sequel/database/schema_methods.rb', line 70

def alter_table(name, generator=nil, &block)
  generator ||= Schema::AlterTableGenerator.new(self, &block)
  remove_cached_schema(name)
  apply_alter_table(name, generator.operations)
  nil
end

#call(ps_name, hash = {}, &block) ⇒ Object

Call the prepared statement with the given name with the given hash of arguments.

DB[:items].filter(:id=>1).prepare(:first, :sa)
DB.call(:sa) # SELECT * FROM items WHERE id = 1



58
59
60
 
# File 'lib/sequel/database/query.rb', line 58

def call(ps_name, hash={}, &block)
  prepared_statement(ps_name).call(hash, &block)
end

#cast_type_literal(type) ⇒ Object

Cast the given type to a literal type

DB.cast_type_literal(Float) # double precision
DB.cast_type_literal(:foo) # foo



106
107
108
 
# File 'lib/sequel/database/misc.rb', line 106

def cast_type_literal(type)
  type_literal(:type=>type)
end

#connect(server) ⇒ Object

Connects to the database. This method should be overridden by descendants.

Raises:



145
146
147
 
# File 'lib/sequel/database/connecting.rb', line 145

def connect(server)
  raise NotImplemented, "#connect should be overridden by adapters"
end

#create_join_table(hash, options = {}) ⇒ Object

Create a join table using a hash of foreign keys to referenced table names. Example:

create_join_table(:cat_id=>:cats, :dog_id=>:dogs)
# CREATE TABLE cats_dogs (
#  cat_id integer NOT NULL REFERENCES cats,
#  dog_id integer NOT NULL REFERENCES dogs,
#  PRIMARY KEY (cat_id, dog_id)
# )
# CREATE INDEX cats_dogs_dog_id_cat_id_index ON cats_dogs(dog_id, cat_id)

The primary key and index are used so that almost all operations on the table can benefit from one of the two indexes, and the primary key ensures that entries in the table are unique, which is the typical desire for a join table.

You can provide column options by making the values in the hash be option hashes, so long as the option hashes have a :table entry giving the table referenced:

create_join_table(:cat_id=>{:table=>:cats, :type=>Bignum}, :dog_id=>:dogs)

You can provide a second argument which is a table options hash:

create_join_table({:cat_id=>:cats, :dog_id=>:dogs}, :temp=>true)

Some table options are handled specially:

:index_options

The options to pass to the index

:name

The name of the table to create

:no_index

Set to true not to create the second index.

:no_primary_key

Set to true to not create the primary key.



109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
 
# File 'lib/sequel/database/schema_methods.rb', line 109

def create_join_table(hash, options={})
  keys = hash.keys.sort_by{|k| k.to_s}
  create_table(join_table_name(hash, options), options) do
    keys.each do |key|
      v = hash[key]
      unless v.is_a?(Hash)
        v = {:table=>v}
      end
      v = DEFAULT_JOIN_TABLE_COLUMN_OPTIONS.merge(v)
      foreign_key(key, v)
    end
    primary_key(keys) unless options[:no_primary_key]
    index(keys.reverse, options[:index_options] || {}) unless options[:no_index]
  end
end

#create_or_replace_view(name, source) ⇒ Object

Creates a view, replacing it if it already exists:

DB.create_or_replace_view(:cheap_items, "SELECT * FROM items WHERE price < 100")
DB.create_or_replace_view(:ruby_items, DB[:items].filter(:category => 'ruby'))



189
190
191
192
193
194
 
# File 'lib/sequel/database/schema_methods.rb', line 189

def create_or_replace_view(name, source)
  source = source.sql if source.is_a?(Dataset)
  execute_ddl("CREATE OR REPLACE VIEW #{quote_schema_table(name)} AS #{source}")
  remove_cached_schema(name)
  nil
end

#create_table(name, options = {}, &block) ⇒ Object

Creates a table with the columns given in the provided block:

DB.create_table :posts do
  primary_key :id
  column :title, :text
  String :content
  index :title
end

General options:

:as

Create the table using the value, which should be either a dataset or a literal SQL string. If this option is used, a block should not be given to the method.

:ignore_index_errors

Ignore any errors when creating indexes.

:temp

Create the table as a temporary table.

MySQL specific options:

:charset

The character set to use for the table.

:collate

The collation to use for the table.

:engine

The table engine to use for the table.

See Schema::Generator and the “Schema Modification” guide.



147
148
149
150
151
152
153
154
155
156
157
158
159
 
# File 'lib/sequel/database/schema_methods.rb', line 147

def create_table(name, options={}, &block)
  remove_cached_schema(name)
  options = {:generator=>options} if options.is_a?(Schema::Generator)
  if sql = options[:as]
    raise(Error, "can't provide both :as option and block to create_table") if block
    create_table_as(name, sql, options)
  else
    generator = options[:generator] || Schema::Generator.new(self, &block)
    create_table_from_generator(name, generator, options)
    create_table_indexes_from_generator(name, generator, options)
    nil
  end
end

#create_table!(name, options = {}, &block) ⇒ Object

Forcibly create a table, attempting to drop it if it already exists, then creating it.

DB.create_table!(:a){Integer :a} 
# SELECT NULL FROM a LIMIT 1 -- check existence
# DROP TABLE a -- drop table if already exists
# CREATE TABLE a (a integer)



167
168
169
170
 
# File 'lib/sequel/database/schema_methods.rb', line 167

def create_table!(name, options={}, &block)
  drop_table?(name)
  create_table(name, options, &block)
end

#create_table?(name, options = {}, &block) ⇒ Boolean

Creates the table unless the table already exists.

DB.create_table?(:a){Integer :a} 
# SELECT NULL FROM a LIMIT 1 -- check existence
# CREATE TABLE a (a integer) -- if it doesn't already exist

Returns:

  • (Boolean) 


177
178
179
180
181
182
183
 
# File 'lib/sequel/database/schema_methods.rb', line 177

def create_table?(name, options={}, &block)
  if supports_create_table_if_not_exists?
    create_table(name, options.merge(:if_not_exists=>true), &block)
  elsif !table_exists?(name)
    create_table(name, options, &block)
  end
end

#create_view(name, source) ⇒ Object

Creates a view based on a dataset or an SQL string:

DB.create_view(:cheap_items, "SELECT * FROM items WHERE price < 100")
DB.create_view(:ruby_items, DB[:items].filter(:category => 'ruby'))



200
201
202
203
 
# File 'lib/sequel/database/schema_methods.rb', line 200

def create_view(name, source)
  source = source.sql if source.is_a?(Dataset)
  execute_ddl("CREATE VIEW #{quote_schema_table(name)} AS #{source}")
end

#database_type ⇒ Object

The database type for this database object, the same as the adapter scheme by default. Should be overridden in adapters (especially shared adapters) to be the correct type, so that even if two separate Database objects are using different adapters you can tell that they are using the same database type. Even better, you can tell that two Database objects that are using the same adapter are connecting to different database types (think JDBC or DataObjects).

Sequel.connect('jdbc:postgres://...').database_type # => :postgres



158
159
160
 
# File 'lib/sequel/database/connecting.rb', line 158

def database_type
  adapter_scheme
end

#dataset(opts = nil) ⇒ Object

Returns a blank dataset for this database.

DB.dataset # SELECT *
DB.dataset.from(:items) # SELECT * FROM items



27
28
29
 
# File 'lib/sequel/database/dataset.rb', line 27

def dataset(opts=nil)
  @dataset_class.new(self, opts)
end

#disconnect(opts = {}) ⇒ Object

Disconnects all available connections from the connection pool. Any connections currently in use will not be disconnected. Options:

:servers

Should be a symbol specifing the server to disconnect from, or an array of symbols to specify multiple servers.

Example:

DB.disconnect # All servers
DB.disconnect(:servers=>:server1) # Single server
DB.disconnect(:servers=>[:server1, :server2]) # Multiple servers



172
173
174
 
# File 'lib/sequel/database/connecting.rb', line 172

def disconnect(opts = {})
  pool.disconnect(opts)
end

#drop_column(table, *args) ⇒ Object

Removes a column from the specified table:

DB.drop_column :items, :category

See alter_table.



210
211
212
 
# File 'lib/sequel/database/schema_methods.rb', line 210

def drop_column(table, *args)
  alter_table(table) {drop_column(*args)}
end

#drop_index(table, columns, options = {}) ⇒ Object

Removes an index for the given table and column/s:

DB.drop_index :posts, :title
DB.drop_index :posts, [:author, :title]

See alter_table.



220
221
222
 
# File 'lib/sequel/database/schema_methods.rb', line 220

def drop_index(table, columns, options={})
  alter_table(table){drop_index(columns, options)}
end

#drop_join_table(hash, options = {}) ⇒ Object

Drop the join table that would have been created with the same arguments to create_join_table:

drop_join_table(:cat_id=>:cats, :dog_id=>:dogs)
# DROP TABLE cats_dogs



229
230
231
 
# File 'lib/sequel/database/schema_methods.rb', line 229

def drop_join_table(hash, options={})
  drop_table(join_table_name(hash, options), options)
end

#drop_table(*names) ⇒ Object

Drops one or more tables corresponding to the given names:

DB.drop_table(:posts) # DROP TABLE posts
DB.drop_table(:posts, :comments)
DB.drop_table(:posts, :comments, :cascade=>true)



238
239
240
241
242
243
244
245
 
# File 'lib/sequel/database/schema_methods.rb', line 238

def drop_table(*names)
  options = names.last.is_a?(Hash) ? names.pop : {}
  names.each do |n|
    execute_ddl(drop_table_sql(n, options))
    remove_cached_schema(n)
  end
  nil
end

#drop_table?(*names) ⇒ Boolean

Drops the table if it already exists. If it doesn’t exist, does nothing.

DB.drop_table?(:a)
# SELECT NULL FROM a LIMIT 1 -- check existence
# DROP TABLE a -- if it already exists

Returns:

  • (Boolean) 


253
254
255
256
257
258
259
260
261
262
263
264
265
 
# File 'lib/sequel/database/schema_methods.rb', line 253

def drop_table?(*names)
  options = names.last.is_a?(Hash) ? names.pop : {}
  if supports_drop_table_if_exists?
    options = options.merge(:if_exists=>true)
    names.each do |name|
      drop_table(name, options)
    end
  else
    names.each do |name|
      drop_table(name, options) if table_exists?(name)
    end
  end
end

#drop_view(*names) ⇒ Object

Drops one or more views corresponding to the given names:

DB.drop_view(:cheap_items)
DB.drop_view(:cheap_items, :pricey_items)
DB.drop_view(:cheap_items, :pricey_items, :cascade=>true)



272
273
274
275
276
277
278
279
 
# File 'lib/sequel/database/schema_methods.rb', line 272

def drop_view(*names)
  options = names.last.is_a?(Hash) ? names.pop : {}
  names.each do |n|
    execute_ddl(drop_view_sql(n, options))
    remove_cached_schema(n)
  end
  nil
end

#dump_foreign_key_migration(options = {}) ⇒ Object

Dump foreign key constraints for all tables as a migration. This complements the :foreign_keys=>false option to dump_schema_migration. This only dumps the constraints (not the columns) using alter_table/add_foreign_key with an array of columns.

Note that the migration this produces does not have a down block, so you cannot reverse it.



16
17
18
19
20
21
22
23
24
25
 
# File 'lib/sequel/extensions/schema_dumper.rb', line 16

def dump_foreign_key_migration(options={})
  ts = tables(options)
  <<END_MIG
Sequel.migration do
  up do
#{ts.sort_by{|t| t.to_s}.map{|t| dump_table_foreign_keys(t)}.reject{|x| x == ''}.join("\n\n").gsub(/^/o, '    ')}
  end
end
END_MIG
end

#dump_indexes_migration(options = {}) ⇒ Object

Dump indexes for all tables as a migration. This complements the :indexes=>false option to dump_schema_migration. Options:

  • :same_db - Create a dump for the same database type, so don’t ignore errors if the index statements fail.

  • :index_names - If set to false, don’t record names of indexes. If set to :namespace, prepend the table name to the index name if the database does not use a global index namespace.



34
35
36
37
38
39
40
41
42
43
44
45
46
47
 
# File 'lib/sequel/extensions/schema_dumper.rb', line 34

def dump_indexes_migration(options={})
  ts = tables(options)
  <<END_MIG
Sequel.migration do
  up do
#{ts.sort_by{|t| t.to_s}.map{|t| dump_table_indexes(t, :add_index, options)}.reject{|x| x == ''}.join("\n\n").gsub(/^/o, '    ')}
  end
  
  down do
#{ts.sort_by{|t| t.to_s}.reverse.map{|t| dump_table_indexes(t, :drop_index, options)}.reject{|x| x == ''}.join("\n\n").gsub(/^/o, '    ')}
  end
end
END_MIG
end

#dump_schema_cache(file) ⇒ Object

Dump the cached schema to the filename given in Marshal format.



52
53
54
55
 
# File 'lib/sequel/extensions/schema_caching.rb', line 52

def dump_schema_cache(file)
  File.open(file, 'wb'){|f| f.write(Marshal.dump(@schemas))}
  nil
end

#dump_schema_cache?(file) ⇒ Boolean

Dump the cached schema to the filename given unless the file already exists.

Returns:

  • (Boolean) 


59
60
61
 
# File 'lib/sequel/extensions/schema_caching.rb', line 59

def dump_schema_cache?(file)
  dump_schema_cache(file) unless File.exist?(file)
end

#dump_schema_migration(options = {}) ⇒ Object

Return a string that contains a Sequel::Migration subclass that when run would recreate the database structure. Options:

  • :same_db - Don’t attempt to translate database types to ruby types. If this isn’t set to true, all database types will be translated to ruby types, but there is no guarantee that the migration generated will yield the same type. Without this set, types that aren’t recognized will be translated to a string-like type.

  • :foreign_keys - If set to false, don’t dump foreign_keys

  • :indexes - If set to false, don’t dump indexes (they can be added later via dump_index_migration).

  • :index_names - If set to false, don’t record names of indexes. If set to :namespace, prepend the table name to the index name.



61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
 
# File 'lib/sequel/extensions/schema_dumper.rb', line 61

def dump_schema_migration(options={})
  options = options.dup
  if options[:indexes] == false && !options.has_key?(:foreign_keys)
    # Unless foreign_keys option is specifically set, disable if indexes
    # are disabled, as foreign keys that point to non-primary keys rely
    # on unique indexes being created first
    options[:foreign_keys] = false
  end

  ts = sort_dumped_tables(tables(options), options)
  skipped_fks = if sfk = options[:skipped_foreign_keys]
    # Handle skipped foreign keys by adding them at the end via
    # alter_table/add_foreign_key.  Note that skipped foreign keys
    # probably result in a broken down migration.
    sfka = sfk.sort_by{|table, fks| table.to_s}.map{|table, fks| dump_add_fk_constraints(table, fks.values)}
    sfka.join("\n\n").gsub(/^/o, '    ') unless sfka.empty?
  end

  <<END_MIG
Sequel.migration do
  up do
#{ts.map{|t| dump_table_schema(t, options)}.join("\n\n").gsub(/^/o, '    ')}#{"\n    \n" if skipped_fks}#{skipped_fks}
  end
  
  down do
drop_table(#{ts.reverse.inspect[1...-1]})
  end
end
END_MIG
end

#dump_table_schema(table, options = {}) ⇒ Object

Return a string with a create table block that will recreate the given table’s schema. Takes the same options as dump_schema_migration.



94
95
96
97
98
99
 
# File 'lib/sequel/extensions/schema_dumper.rb', line 94

def dump_table_schema(table, options={})
  table = table.value.to_s if table.is_a?(SQL::Identifier)
  gen = dump_table_generator(table, options)
  commands = [gen.dump_columns, gen.dump_constraints, gen.dump_indexes].reject{|x| x == ''}.join("\n\n")
  "create_table(#{table.inspect}#{', :ignore_index_errors=>true' if !options[:same_db] && options[:indexes] != false && !gen.indexes.empty?}) do\n#{commands.gsub(/^/o, '  ')}\nend"
end

#each_server(&block) ⇒ Object

Yield a new Database instance for every server in the connection pool. Intended for use in sharded environments where there is a need to make schema modifications (DDL queries) on each shard.

DB.each_server{|db| db.create_table(:users){primary_key :id; String :name}}



181
182
183
 
# File 'lib/sequel/database/connecting.rb', line 181

def each_server(&block)
  servers.each{|s| self.class.connect(server_opts(s), &block)}
end

#execute(sql, opts = {}) ⇒ Object

Executes the given SQL on the database. This method should be overridden in descendants. This method should not be called directly by user code.

Raises:



64
65
66
 
# File 'lib/sequel/database/query.rb', line 64

def execute(sql, opts={})
  raise NotImplemented, "#execute should be overridden by adapters"
end

#execute_ddl(sql, opts = {}, &block) ⇒ Object

Method that should be used when submitting any DDL (Data Definition Language) SQL, such as create_table. By default, calls execute_dui. This method should not be called directly by user code.



71
72
73
 
# File 'lib/sequel/database/query.rb', line 71

def execute_ddl(sql, opts={}, &block)
  execute_dui(sql, opts, &block)
end

#execute_dui(sql, opts = {}, &block) ⇒ Object

Method that should be used when issuing a DELETE, UPDATE, or INSERT statement. By default, calls execute. This method should not be called directly by user code.



78
79
80
 
# File 'lib/sequel/database/query.rb', line 78

def execute_dui(sql, opts={}, &block)
  execute(sql, opts, &block)
end

#execute_insert(sql, opts = {}, &block) ⇒ Object

Method that should be used when issuing a INSERT statement. By default, calls execute_dui. This method should not be called directly by user code.



85
86
87
 
# File 'lib/sequel/database/query.rb', line 85

def execute_insert(sql, opts={}, &block)
  execute_dui(sql, opts, &block)
end

#extend_datasets(mod = nil, &block) ⇒ Object

Equivalent to extending all datasets produced by the database with a module. What it actually does is use a subclass of the current dataset_class as the new dataset_class, and include the module in the subclass. Instead of a module, you can provide a block that is used to create an anonymous module.

This allows you to override any of the dataset methods even if they are defined directly on the dataset class that this Database object uses.

Examples:

# Introspec columns for all of DB's datasets
DB.extend_datasets(Sequel::ColumnsIntrospection)

# Trace all SELECT queries by printing the SQL and the full backtrace
DB.extend_datasets do
  def fetch_rows(sql)
    puts sql
    puts caller
    super
  end
end

Raises:



91
92
93
94
95
96
97
98
99
100
101
102
 
# File 'lib/sequel/database/dataset_defaults.rb', line 91

def extend_datasets(mod=nil, &block)
  raise(Error, "must provide either mod or block, not both") if mod && block
  reset_schema_utility_dataset
  mod = Module.new(&block) if block
  if @dataset_modules.empty?
   @dataset_modules = [mod]
   @dataset_class = Class.new(@dataset_class)
  else
   @dataset_modules << mod
  end
  @dataset_class.send(:include, mod)
end

#fetch(sql, *args, &block) ⇒ Object

Fetches records for an arbitrary SQL statement. If a block is given, it is used to iterate over the records:

DB.fetch('SELECT * FROM items'){|r| p r}

The fetch method returns a dataset instance:

DB.fetch('SELECT * FROM items').all

fetch can also perform parameterized queries for protection against SQL injection:

DB.fetch('SELECT * FROM items WHERE name = ?', my_name).all



44
45
46
47
48
 
# File 'lib/sequel/database/dataset.rb', line 44

def fetch(sql, *args, &block)
  ds = dataset.with_sql(sql, *args)
  ds.each(&block) if block
  ds
end

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

Returns an array of hashes containing foreign key information from the table. Each hash will contain at least the following fields:

:columns

An array of columns in the given table

:table

The table referenced by the columns

:key

An array of columns referenced (in the table specified by :table), but can be nil on certain adapters if the primary key is referenced.

The hash may also contain entries for:

:deferrable

Whether the constraint is deferrable

:name

The name of the constraint

:on_delete

The action to take ON DELETE

:on_update

The action to take ON UPDATE

Raises:



103
104
105
 
# File 'lib/sequel/database/query.rb', line 103

def foreign_key_list(table, opts={})
  raise NotImplemented, "#foreign_key_list should be overridden by adapters"
end

#from(*args, &block) ⇒ Object

Returns a new dataset with the from method invoked. If a block is given, it is used as a filter on the dataset.

DB.from(:items) # SELECT * FROM items
DB.from(:items){id > 2} # SELECT * FROM items WHERE (id > 2)



55
56
57
58
 
# File 'lib/sequel/database/dataset.rb', line 55

def from(*args, &block)
  ds = dataset.from(*args)
  block ? ds.filter(&block) : ds
end

#from_application_timestamp(v) ⇒ Object

Convert the given timestamp from the application’s timezone, to the databases’s timezone or the default database timezone if the database does not have a timezone.



113
114
115
 
# File 'lib/sequel/database/misc.rb', line 113

def from_application_timestamp(v)
  Sequel.convert_output_timestamp(v, timezone)
end

#get(*args, &block) ⇒ Object

Returns a single value from the database, e.g.:

DB.get(1) # SELECT 1
# => 1
DB.get{server_version{}} # SELECT server_version()



112
113
114
 
# File 'lib/sequel/database/query.rb', line 112

def get(*args, &block)
  dataset.get(*args, &block)
end

#global_index_namespace? ⇒ Boolean

Whether the database uses a global namespace for the index. If false, the indexes are going to be namespaced per table.

Returns:

  • (Boolean) 


119
120
121
 
# File 'lib/sequel/database/misc.rb', line 119

def global_index_namespace?
  true
end

#identifier_input_method ⇒ Object

The method to call on identifiers going into the database



105
106
107
108
109
110
111
112
113
114
115
 
# File 'lib/sequel/database/dataset_defaults.rb', line 105

def identifier_input_method
  case @identifier_input_method
  when nil
    @identifier_input_method = @opts.fetch(:identifier_input_method, (@@identifier_input_method.nil? ? identifier_input_method_default : @@identifier_input_method))
    @identifier_input_method == "" ? nil : @identifier_input_method
  when ""
    nil
  else
    @identifier_input_method
  end
end

#identifier_input_method=(v) ⇒ Object

Set the method to call on identifiers going into the database:

DB[:items] # SELECT * FROM items
DB.identifier_input_method = :upcase
DB[:items] # SELECT * FROM ITEMS



122
123
124
125
 
# File 'lib/sequel/database/dataset_defaults.rb', line 122

def identifier_input_method=(v)
  reset_schema_utility_dataset
  @identifier_input_method = v || ""
end

#identifier_output_method ⇒ Object

The method to call on identifiers coming from the database



128
129
130
131
132
133
134
135
136
137
138
 
# File 'lib/sequel/database/dataset_defaults.rb', line 128

def identifier_output_method
  case @identifier_output_method
  when nil
    @identifier_output_method = @opts.fetch(:identifier_output_method, (@@identifier_output_method.nil? ? identifier_output_method_default : @@identifier_output_method))
    @identifier_output_method == "" ? nil : @identifier_output_method
  when ""
    nil
  else
    @identifier_output_method
  end
end

#identifier_output_method=(v) ⇒ Object

Set the method to call on identifiers coming from the database:

DB[:items].first # {:id=>1, :name=>'foo'}
DB.identifier_output_method = :upcase
DB[:items].first # {:ID=>1, :NAME=>'foo'}



145
146
147
148
 
# File 'lib/sequel/database/dataset_defaults.rb', line 145

def identifier_output_method=(v)
  reset_schema_utility_dataset
  @identifier_output_method = v || ""
end

#in_transaction?(opts = {}) ⇒ Boolean

Return true if already in a transaction given the options, false otherwise. Respects the :server option for selecting a shard.

Returns:

  • (Boolean) 


126
127
128
 
# File 'lib/sequel/database/misc.rb', line 126

def in_transaction?(opts={})
  synchronize(opts[:server]){|conn| !!_trans(conn)}
end

#indexes(table, opts = {}) ⇒ Object

Return a hash containing index information for the table. Hash keys are index name symbols. Values are subhashes with two keys, :columns and :unique. The value of :columns is an array of symbols of column names. The value of :unique is true or false depending on if the index is unique.

Should not include the primary key index, functional indexes, or partial indexes.

DB.indexes(:artists)
# => {:artists_name_ukey=>{:columns=>[:name], :unique=>true}}

Raises:



125
126
127
 
# File 'lib/sequel/database/query.rb', line 125

def indexes(table, opts={})
  raise NotImplemented, "#indexes should be overridden by adapters"
end

#inspect ⇒ Object

Returns a string representation of the database object including the class name and connection URI and options used when connecting (if any).



132
133
134
135
136
137
138
139
 
# File 'lib/sequel/database/misc.rb', line 132

def inspect
  a = []
  a << uri.inspect if uri
  if (oo = opts[:orig_opts]) && !oo.empty?
    a << oo.inspect
  end
  "#<#{self.class}: #{a.join(' ')}>"
end

#literal(v) ⇒ Object

Proxy the literal call to the dataset.

DB.literal(1) # 1
DB.literal(:a) # a
DB.literal('a') # 'a'



146
147
148
 
# File 'lib/sequel/database/misc.rb', line 146

def literal(v)
  schema_utility_dataset.literal(v)
end

#load_schema_cache(file) ⇒ Object

Replace the schema cache with the data from the given file, which should be in Marshal format.



65
66
67
68
 
# File 'lib/sequel/extensions/schema_caching.rb', line 65

def load_schema_cache(file)
  @schemas = Marshal.load(File.read(file))
  nil
end

#load_schema_cache?(file) ⇒ Boolean

Replace the schema cache with the data from the given file if the file exists.

Returns:

  • (Boolean) 


72
73
74
 
# File 'lib/sequel/extensions/schema_caching.rb', line 72

def load_schema_cache?(file)
  load_schema_cache(file) if File.exist?(file)
end

#log_exception(exception, message) ⇒ Object

Log a message at error level, with information about the exception.



21
22
23
 
# File 'lib/sequel/database/logging.rb', line 21

def log_exception(exception, message)
  log_each(:error, "#{exception.class}: #{exception.message.strip}: #{message}")
end

#log_info(message, args = nil) ⇒ Object

Log a message at level info to all loggers.



26
27
28
 
# File 'lib/sequel/database/logging.rb', line 26

def log_info(message, args=nil)
  log_each(:info, args ? "#{message}; #{args.inspect}" : message)
end

#log_yield(sql, args = nil) ⇒ Object

Yield to the block, logging any errors at error level to all loggers, and all other queries with the duration at warn or info level.



32
33
34
35
36
37
38
39
40
41
42
43
44
 
# File 'lib/sequel/database/logging.rb', line 32

def log_yield(sql, args=nil)
  return yield if @loggers.empty?
  sql = "#{sql}; #{args.inspect}" if args
  start = Time.now
  begin
    yield
  rescue => e
    log_exception(e, sql)
    raise
  ensure
    log_duration(Time.now - start, sql) unless e
  end
end

#logger=(logger) ⇒ Object

Remove any existing loggers and just use the given logger:

DB.logger = Logger.new($stdout)



49
50
51
 
# File 'lib/sequel/database/logging.rb', line 49

def logger=(logger)
  @loggers = Array(logger)
end

#prepared_statement(name) ⇒ Object

Synchronize access to the prepared statements cache.



151
152
153
 
# File 'lib/sequel/database/misc.rb', line 151

def prepared_statement(name)
  Sequel.synchronize{prepared_statements[name]}
end

#query(&block) ⇒ Object

Return a dataset modified by the query block



8
9
10
 
# File 'lib/sequel/extensions/query.rb', line 8

def query(&block)
  dataset.query(&block)
end

#quote_identifiers=(v) ⇒ Object

Set whether to quote identifiers (columns and tables) for this database:

DB[:items] # SELECT * FROM items
DB.quote_identifiers = true
DB[:items] # SELECT * FROM "items"



155
156
157
158
 
# File 'lib/sequel/database/dataset_defaults.rb', line 155

def quote_identifiers=(v)
  reset_schema_utility_dataset
  @quote_identifiers = v
end

#quote_identifiers? ⇒ Boolean

Returns true if the database quotes identifiers.

Returns:

  • (Boolean) 


161
162
163
164
 
# File 'lib/sequel/database/dataset_defaults.rb', line 161

def quote_identifiers?
  return @quote_identifiers unless @quote_identifiers.nil?
  @quote_identifiers = @opts.fetch(:quote_identifiers, (@@quote_identifiers.nil? ? quote_identifiers_default : @@quote_identifiers))
end

#remove_servers(*servers) ⇒ Object

Dynamically remove existing servers from the connection pool. Intended for use with master/slave or shard configurations where it is useful to remove existing server hosts at runtime.

servers should be symbols or arrays of symbols. If a nonexistent server is specified, it is ignored. If no servers have been specified for this database, no changes are made. If you attempt to remove the :default server, an error will be raised.

DB.remove_servers(:f1, :f2)



195
196
197
198
199
200
 
# File 'lib/sequel/database/connecting.rb', line 195

def remove_servers(*servers)
  if h = @opts[:servers]
    servers.flatten.each{|s| Sequel.synchronize{h.delete(s)}}
    @pool.remove_servers(servers)
  end
end

#rename_column(table, *args) ⇒ Object

Renames a column in the specified table. This method expects the current column name and the new column name:

DB.rename_column :items, :cntr, :counter

See alter_table.



298
299
300
 
# File 'lib/sequel/database/schema_methods.rb', line 298

def rename_column(table, *args)
  alter_table(table) {rename_column(*args)}
end

#rename_table(name, new_name) ⇒ Object

Renames a table:

DB.tables #=> [:items]
DB.rename_table :items, :old_items
DB.tables #=> [:old_items]



286
287
288
289
290
 
# File 'lib/sequel/database/schema_methods.rb', line 286

def rename_table(name, new_name)
  execute_ddl(rename_table_sql(name, new_name))
  remove_cached_schema(name)
  nil
end

#run(sql, opts = {}) ⇒ Object

Runs the supplied SQL statement string on the database server. Returns nil. Options:

:server

The server to run the SQL on.

DB.run("SET some_server_variable = 42")



134
135
136
137
 
# File 'lib/sequel/database/query.rb', line 134

def run(sql, opts={})
  execute_ddl(sql, opts)
  nil
end

#schema(table, opts = {}) ⇒ Object

Returns the schema for the given table as an array with all members being arrays of length 2, the first member being the column name, and the second member being a hash of column information. The table argument can also be a dataset, as long as it only has one table. Available options are:

:reload

Ignore any cached results, and get fresh information from the database.

:schema

An explicit schema to use. It may also be implicitly provided via the table name.

If schema parsing is supported by the database, the column information should hash at least contain the following entries:

:allow_null

Whether NULL is an allowed value for the column.

:db_type

The database type for the column, as a database specific string.

:default

The database default for the column, as a database specific string.

:primary_key

Whether the columns is a primary key column. If this column is not present, it means that primary key information is unavailable, not that the column is not a primary key.

:ruby_default

The database default for the column, as a ruby object. In many cases, complex database defaults cannot be parsed into ruby objects, in which case nil will be used as the value.

:type

A symbol specifying the type, such as :integer or :string.

Example:

DB.schema(:artists)
# [[:id,
#   {:type=>:integer,
#    :primary_key=>true,
#    :default=>"nextval('artist_id_seq'::regclass)",
#    :ruby_default=>nil,
#    :db_type=>"integer",
#    :allow_null=>false}],
#  [:name,
#   {:type=>:string,
#    :primary_key=>false,
#    :default=>nil,
#    :ruby_default=>nil,
#    :db_type=>"text",
#    :allow_null=>false}]]

Raises:



179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
 
# File 'lib/sequel/database/query.rb', line 179

def schema(table, opts={})
  raise(Error, 'schema parsing is not implemented on this database') unless respond_to?(:schema_parse_table, true)

  opts = opts.dup
  if table.is_a?(Dataset)
    o = table.opts
    from = o[:from]
    raise(Error, "can only parse the schema for a dataset with a single from table") unless from && from.length == 1 && !o.include?(:join) && !o.include?(:sql)
    tab = table.first_source_table
    sch, table_name = schema_and_table(tab)
    quoted_name = table.literal(tab)
    opts[:dataset] = table
  else
    sch, table_name = schema_and_table(table)
    quoted_name = quote_schema_table(table)
  end
  opts[:schema] = sch if sch && !opts.include?(:schema)

  Sequel.synchronize{@schemas.delete(quoted_name)} if opts[:reload]
  return Sequel.synchronize{@schemas[quoted_name]} if @schemas[quoted_name]

  cols = schema_parse_table(table_name, opts)
  raise(Error, 'schema parsing returned no columns, table probably doesn\'t exist') if cols.nil? || cols.empty?
  cols.each{|_,c| c[:ruby_default] = column_schema_to_ruby_default(c[:default], c[:type])}
  Sequel.synchronize{@schemas[quoted_name] = cols} if cache_schema
  cols
end

#select(*args, &block) ⇒ Object

Returns a new dataset with the select method invoked.

DB.select(1) # SELECT 1
DB.select{server_version{}} # SELECT server_version()
DB.select(:id).from(:items) # SELECT id FROM items



65
66
67
 
# File 'lib/sequel/database/dataset.rb', line 65

def select(*args, &block)
  dataset.select(*args, &block)
end

#serial_primary_key_options ⇒ Object

Default serial primary key options, used by the table creation code.



157
158
159
 
# File 'lib/sequel/database/misc.rb', line 157

def serial_primary_key_options
  {:primary_key => true, :type => Integer, :auto_increment => true}
end

#servers ⇒ Object

An array of servers/shards for this Database object.

DB.servers # Unsharded: => [:default]
DB.servers # Sharded:   => [:default, :server1, :server2]



206
207
208
 
# File 'lib/sequel/database/connecting.rb', line 206

def servers
  pool.servers
end

#set_column_default(table, *args) ⇒ Object

Sets the default value for the given column in the given table:

DB.set_column_default :items, :category, 'perl!'

See alter_table.



307
308
309
 
# File 'lib/sequel/database/schema_methods.rb', line 307

def set_column_default(table, *args)
  alter_table(table) {set_column_default(*args)}
end

#set_column_type(table, *args) ⇒ Object

Set the data type for the given column in the given table:

DB.set_column_type :items, :price, :float

See alter_table.



316
317
318
 
# File 'lib/sequel/database/schema_methods.rb', line 316

def set_column_type(table, *args)
  alter_table(table) {set_column_type(*args)}
end

#set_prepared_statement(name, ps) ⇒ Object

Cache the prepared statement object at the given name.



162
163
164
 
# File 'lib/sequel/database/misc.rb', line 162

def set_prepared_statement(name, ps)
  Sequel.synchronize{prepared_statements[name] = ps}
end

#single_threaded? ⇒ Boolean

Returns true if the database is using a single-threaded connection pool.

Returns:

  • (Boolean) 


211
212
213
 
# File 'lib/sequel/database/connecting.rb', line 211

def single_threaded?
  @single_threaded
end

#supports_create_table_if_not_exists? ⇒ Boolean

Whether the database supports CREATE TABLE IF NOT EXISTS syntax, false by default.

Returns:

  • (Boolean) 


168
169
170
 
# File 'lib/sequel/database/misc.rb', line 168

def supports_create_table_if_not_exists?
  false
end

#supports_drop_table_if_exists? ⇒ Boolean

Whether the database supports DROP TABLE IF EXISTS syntax, default is the same as #supports_create_table_if_not_exists?.

Returns:

  • (Boolean) 


174
175
176
 
# File 'lib/sequel/database/misc.rb', line 174

def supports_drop_table_if_exists?
  supports_create_table_if_not_exists?
end

#supports_prepared_transactions? ⇒ Boolean

Whether the database and adapter support prepared transactions (two-phase commit), false by default.

Returns:

  • (Boolean) 


180
181
182
 
# File 'lib/sequel/database/misc.rb', line 180

def supports_prepared_transactions?
  false
end

#supports_savepoints? ⇒ Boolean

Whether the database and adapter support savepoints, false by default.

Returns:

  • (Boolean) 


185
186
187
 
# File 'lib/sequel/database/misc.rb', line 185

def supports_savepoints?
  false
end

#supports_savepoints_in_prepared_transactions? ⇒ Boolean

Whether the database and adapter support savepoints inside prepared transactions (two-phase commit), default is false.

Returns:

  • (Boolean) 


191
192
193
 
# File 'lib/sequel/database/misc.rb', line 191

def supports_savepoints_in_prepared_transactions?
  supports_prepared_transactions? && supports_savepoints?
end

#supports_transaction_isolation_levels? ⇒ Boolean

Whether the database and adapter support transaction isolation levels, false by default.

Returns:

  • (Boolean) 


196
197
198
 
# File 'lib/sequel/database/misc.rb', line 196

def supports_transaction_isolation_levels?
  false
end

#supports_transactional_ddl? ⇒ Boolean

Whether DDL statements work correctly in transactions, false by default.

Returns:

  • (Boolean) 


201
202
203
 
# File 'lib/sequel/database/misc.rb', line 201

def supports_transactional_ddl?
  false
end

#synchronize(server = nil, &block) ⇒ Object

Acquires a database connection, yielding it to the passed block. This is useful if you want to make sure the same connection is used for all database queries in the block. It is also useful if you want to gain direct access to the underlying connection object if you need to do something Sequel does not natively support.

If a server option is given, acquires a connection for that specific server, instead of the :default server.

DB.synchronize do |conn|
  ...
end



228
229
230
 
# File 'lib/sequel/database/connecting.rb', line 228

def synchronize(server=nil)
  @pool.hold(server || :default){|conn| yield conn}
end

#table_exists?(name) ⇒ Boolean

Returns true if a table with the given name exists. This requires a query to the database.

DB.table_exists?(:foo) # => false
# SELECT NULL FROM foo LIMIT 1

Note that since this does a SELECT from the table, it can give false negatives if you don’t have permission to SELECT from the table.

Returns:

  • (Boolean) 


215
216
217
218
219
220
221
222
 
# File 'lib/sequel/database/query.rb', line 215

def table_exists?(name)
  sch, table_name = schema_and_table(name)
  name = SQL::QualifiedIdentifier.new(sch, table_name) if sch
  _table_exists?(from(name))
  true
rescue DatabaseError
  false
end

#tables(opts = {}) ⇒ Object

Return all tables in the database as an array of symbols.

DB.tables # => [:albums, :artists]

Raises:



227
228
229
 
# File 'lib/sequel/database/query.rb', line 227

def tables(opts={})
  raise NotImplemented, "#tables should be overridden by adapters"
end

#test_connection(server = nil) ⇒ Object

Attempts to acquire a database connection. Returns true if successful. Will probably raise an Error if unsuccessful. If a server argument is given, attempts to acquire a database connection to the given server/shard.



241
242
243
244
 
# File 'lib/sequel/database/connecting.rb', line 241

def test_connection(server=nil)
  synchronize(server){|conn|}
  true
end

#to_application_timestamp(v) ⇒ Object

Convert the given timestamp to the application’s timezone, from the databases’s timezone or the default database timezone if the database does not have a timezone.



213
214
215
 
# File 'lib/sequel/database/misc.rb', line 213

def to_application_timestamp(v)
  Sequel.convert_timestamp(v, timezone)
end

#transaction(opts = {}, &block) ⇒ Object

Starts a database transaction. When a database transaction is used, either all statements are successful or none of the statements are successful. Note that MySQL MyISAM tabels do not support transactions.

The following general options are respected:

:isolation

The transaction isolation level to use for this transaction, should be :uncommitted, :committed, :repeatable, or :serializable, used if given and the database/adapter supports customizable transaction isolation levels.

:prepare

A string to use as the transaction identifier for a prepared transaction (two-phase commit), if the database/adapter supports prepared transactions.

:rollback

Can the set to :reraise to reraise any Sequel::Rollback exceptions raised, or :always to always rollback even if no exceptions occur (useful for testing).

:server

The server to use for the transaction.

:savepoint

Whether to create a new savepoint for this transaction, only respected if the database/adapter supports savepoints. By default Sequel will reuse an existing transaction, so if you want to use a savepoint you must use this option.

PostgreSQL specific options:

:deferrable

(9.1+) If present, set to DEFERRABLE if true or NOT DEFERRABLE if false.

:read_only

If present, set to READ ONLY if true or READ WRITE if false.

:synchronous

if non-nil, set synchronous_commit appropriately. Valid values true, :on, false, :off, :local (9.1+), and :remote_write (9.2+).



260
261
262
263
264
265
 
# File 'lib/sequel/database/query.rb', line 260

def transaction(opts={}, &block)
  synchronize(opts[:server]) do |conn|
    return yield(conn) if already_in_transaction?(conn, opts)
    _transaction(conn, opts, &block)
  end
end

#typecast_value(column_type, value) ⇒ Object

Typecast the value to the given column_type. Calls typecast_value_#column_type if the method exists, otherwise returns the value. This method should raise Sequel::InvalidValue if assigned value is invalid.



222
223
224
225
226
227
228
229
230
 
# File 'lib/sequel/database/misc.rb', line 222

def typecast_value(column_type, value)
  return nil if value.nil?
  meth = "typecast_value_#{column_type}"
  begin
    respond_to?(meth, true) ? send(meth, value) : value
  rescue ArgumentError, TypeError => e
    raise Sequel.convert_exception_class(e, InvalidValue)
  end
end

#uri ⇒ Object

Returns the URI use to connect to the database. If a URI was not used when connecting, returns nil.



234
235
236
 
# File 'lib/sequel/database/misc.rb', line 234

def uri
  opts[:uri]
end

#url ⇒ Object

Explicit alias of uri for easier subclassing.



239
240
241
 
# File 'lib/sequel/database/misc.rb', line 239

def url
  uri
end

#views(opts = {}) ⇒ Object

Return all views in the database as an array of symbols.

DB.views # => [:gold_albums, :artists_with_many_albums]

Raises:



270
271
272
 
# File 'lib/sequel/database/query.rb', line 270

def views(opts={})
  raise NotImplemented, "#views should be overridden by adapters"
end