class Sequel::Database

  1. lib/sequel/database.rb
  2. lib/sequel/database/connecting.rb
  3. lib/sequel/database/dataset.rb
  4. lib/sequel/database/dataset_defaults.rb
  5. lib/sequel/database/features.rb
  6. lib/sequel/database/logging.rb
  7. lib/sequel/database/misc.rb
  8. lib/sequel/database/query.rb
  9. lib/sequel/database/schema_methods.rb
  10. lib/sequel/database/transactions.rb
  11. show all
Superclass: Object

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.

Methods

Public Class

  1. adapter_class
  2. adapter_scheme
  3. after_initialize
  4. connect
  5. extension
  6. load_adapter
  7. new
  8. register_extension
  9. run_after_initialize
  10. set_shared_adapter_scheme

Public Instance

  1. <<
  2. []
  3. adapter_scheme
  4. add_column
  5. add_index
  6. add_servers
  7. after_commit
  8. after_rollback
  9. alter_table
  10. alter_table_generator
  11. cache_schema
  12. call
  13. cast_type_literal
  14. check_string_typecast_bytesize
  15. create_join_table
  16. create_join_table!
  17. create_join_table?
  18. create_or_replace_view
  19. create_table
  20. create_table!
  21. create_table?
  22. create_table_generator
  23. create_view
  24. database_type
  25. dataset
  26. dataset_class
  27. dataset_class=
  28. default_string_column_size
  29. disconnect
  30. disconnect_connection
  31. drop_column
  32. drop_index
  33. drop_join_table
  34. drop_table
  35. drop_table?
  36. drop_view
  37. execute_ddl
  38. execute_dui
  39. execute_insert
  40. extend_datasets
  41. extension
  42. fetch
  43. freeze
  44. from
  45. from_application_timestamp
  46. get
  47. global_index_namespace?
  48. in_transaction?
  49. inspect
  50. literal
  51. literal_symbol
  52. literal_symbol_set
  53. log_connection_info
  54. log_connection_yield
  55. log_exception
  56. log_info
  57. log_warn_duration
  58. logger=
  59. loggers
  60. new_connection
  61. opts
  62. pool
  63. prepared_statement
  64. prepared_statements
  65. quote_identifier
  66. remove_servers
  67. rename_column
  68. rename_table
  69. rollback_checker
  70. rollback_on_exit
  71. run
  72. schema
  73. schema_type_class
  74. select
  75. serial_primary_key_options
  76. servers
  77. set_column_default
  78. set_column_type
  79. set_prepared_statement
  80. sharded?
  81. single_threaded?
  82. sql_log_level
  83. supports_create_table_if_not_exists?
  84. supports_deferrable_constraints?
  85. supports_deferrable_foreign_key_constraints?
  86. supports_drop_table_if_exists?
  87. supports_foreign_key_parsing?
  88. supports_index_parsing?
  89. supports_partial_indexes?
  90. supports_prepared_transactions?
  91. supports_savepoints?
  92. supports_savepoints_in_prepared_transactions?
  93. supports_schema_parsing?
  94. supports_table_listing?
  95. supports_transaction_isolation_levels?
  96. supports_transactional_ddl?
  97. supports_view_listing?
  98. supports_views_with_check_option?
  99. supports_views_with_local_check_option?
  100. synchronize
  101. table_exists?
  102. test_connection
  103. timezone
  104. timezone
  105. to_application_timestamp
  106. transaction
  107. transaction_isolation_level
  108. typecast_value
  109. uri
  110. url
  111. valid_connection?

Constants

OPTS = Sequel::OPTS  

1 - Methods that execute queries and/or return results

Constants

COLUMN_SCHEMA_DATETIME_TYPES = [:date, :datetime].freeze  
COLUMN_SCHEMA_STRING_TYPES = [:string, :blob, :date, :datetime, :time, :enum, :set, :interval].freeze  
INTEGER1_MIN_MAX = [-128, 127].freeze  
INTEGER2_MIN_MAX = [-32768, 32767].freeze  
INTEGER3_MIN_MAX = [-8388608, 8388607].freeze  
INTEGER4_MIN_MAX = [-2147483648, 2147483647].freeze  
INTEGER8_MIN_MAX = [-9223372036854775808, 9223372036854775807].freeze  
UNSIGNED_INTEGER1_MIN_MAX = [0, 255].freeze  
UNSIGNED_INTEGER2_MIN_MAX = [0, 65535].freeze  
UNSIGNED_INTEGER3_MIN_MAX = [0, 16777215].freeze  
UNSIGNED_INTEGER4_MIN_MAX = [0, 4294967295].freeze  
UNSIGNED_INTEGER8_MIN_MAX = [0, 18446744073709551615].freeze  

Attributes

cache_schema [RW]

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.

prepared_statements [R]

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

Public Instance methods

<<(sql)

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"
[show source]
   # File lib/sequel/database/query.rb
25 def <<(sql)
26   run(sql)
27   self
28 end
call(ps_name, hash=OPTS, &block)

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

DB[:items].where(id: 1).prepare(:first, :sa)
DB.call(:sa) # SELECT * FROM items WHERE id = 1
[show source]
   # File lib/sequel/database/query.rb
35 def call(ps_name, hash=OPTS, &block)
36   prepared_statement(ps_name).call(hash, &block)
37 end
execute_ddl(sql, opts=OPTS, &block)

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.

[show source]
   # File lib/sequel/database/query.rb
42 def execute_ddl(sql, opts=OPTS, &block)
43   execute_dui(sql, opts, &block)
44 end
execute_dui(sql, opts=OPTS, &block)

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

[show source]
   # File lib/sequel/database/query.rb
49 def execute_dui(sql, opts=OPTS, &block)
50   execute(sql, opts, &block)
51 end
execute_insert(sql, opts=OPTS, &block)

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.

[show source]
   # File lib/sequel/database/query.rb
56 def execute_insert(sql, opts=OPTS, &block)
57   execute_dui(sql, opts, &block)
58 end
get(*args, &block)

Returns a single value from the database, see Dataset#get.

DB.get(1) # SELECT 1
# => 1
DB.get{server_version.function} # SELECT server_version()
[show source]
   # File lib/sequel/database/query.rb
65 def get(*args, &block)
66   @default_dataset.get(*args, &block)
67 end
run(sql, opts=OPTS)

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")
[show source]
   # File lib/sequel/database/query.rb
74 def run(sql, opts=OPTS)
75   sql = literal(sql) if sql.is_a?(SQL::PlaceholderLiteralString)
76   execute_ddl(sql, opts)
77   nil
78 end
schema(table, opts=OPTS)

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 hash should contain at least 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, or nil if there is no default value.

: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}]]
[show source]
    # File lib/sequel/database/query.rb
121 def schema(table, opts=OPTS)
122   raise(Error, 'schema parsing is not implemented on this database') unless supports_schema_parsing?
123 
124   opts = opts.dup
125   tab = if table.is_a?(Dataset)
126     o = table.opts
127     from = o[:from]
128     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)
129     table.first_source_table
130   else
131     table
132   end
133 
134   qualifiers = split_qualifiers(tab)
135   table_name = qualifiers.pop
136   sch = qualifiers.pop
137   information_schema_schema = case qualifiers.length
138   when 1
139     Sequel.identifier(*qualifiers)
140   when 2
141     Sequel.qualify(*qualifiers)
142   end
143 
144   if table.is_a?(Dataset)
145     quoted_name = table.literal(tab)
146     opts[:dataset] = table
147   else
148     quoted_name = schema_utility_dataset.literal(table)
149   end
150 
151   opts[:schema] = sch if sch && !opts.include?(:schema)
152   opts[:information_schema_schema] = information_schema_schema if information_schema_schema && !opts.include?(:information_schema_schema)
153 
154   Sequel.synchronize{@schemas.delete(quoted_name)} if opts[:reload]
155   if v = Sequel.synchronize{@schemas[quoted_name]}
156     return v
157   end
158 
159   cols = schema_parse_table(table_name, opts)
160   raise(Error, "schema parsing returned no columns, table #{table_name.inspect} probably doesn't exist") if cols.nil? || cols.empty?
161 
162   primary_keys = 0
163   auto_increment_set = false
164   cols.each do |_,c|
165     auto_increment_set = true if c.has_key?(:auto_increment)
166     primary_keys += 1 if c[:primary_key]
167   end
168 
169   cols.each do |_,c|
170     c[:ruby_default] = column_schema_to_ruby_default(c[:default], c[:type]) unless c.has_key?(:ruby_default)
171     if c[:primary_key] && !auto_increment_set
172       # If adapter didn't set it, assume that integer primary keys are auto incrementing
173       c[:auto_increment] = primary_keys == 1 && !!(c[:db_type] =~ /int/io)
174     end
175     if !c[:max_length] && c[:type] == :string && (max_length = column_schema_max_length(c[:db_type]))
176       c[:max_length] = max_length
177     end
178     if !c[:max_value] && !c[:min_value]
179       min_max = case c[:type]
180       when :integer
181         column_schema_integer_min_max_values(c)
182       when :decimal
183         column_schema_decimal_min_max_values(c)
184       end
185       c[:min_value], c[:max_value] = min_max if min_max
186     end
187   end
188   schema_post_process(cols)
189 
190   Sequel.synchronize{@schemas[quoted_name] = cols} if cache_schema
191   cols
192 end
table_exists?(name)

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.

[show source]
    # File lib/sequel/database/query.rb
202 def table_exists?(name)
203   sch, table_name = schema_and_table(name)
204   name = SQL::QualifiedIdentifier.new(sch, table_name) if sch
205   ds = from(name)
206   transaction(:savepoint=>:only){_table_exists?(ds)}
207   true
208 rescue DatabaseError
209   false
210 end

2 - Methods that modify the database schema

Constants

COLUMN_DEFINITION_ORDER = [:collate, :default, :null, :unique, :primary_key, :auto_increment, :references].freeze  

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

COMBINABLE_ALTER_TABLE_OPS = [:add_column, :drop_column, :rename_column, :set_column_type, :set_column_default, :set_column_null, :add_constraint, :drop_constraint].freeze  

The alter table operations that are combinable.

Public Instance methods

add_column(table, *args)

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, String, unique: true, null: false
DB.add_column :items, :category, String, default: 'ruby'

See alter_table.

[show source]
   # File lib/sequel/database/schema_methods.rb
25 def add_column(table, *args)
26   alter_table(table) {add_column(*args)}
27 end
add_index(table, columns, options=OPTS)

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

:name

Name to use for index instead of default

See alter_table.

[show source]
   # File lib/sequel/database/schema_methods.rb
40 def add_index(table, columns, options=OPTS)
41   e = options[:ignore_errors]
42   begin
43     alter_table(table){add_index(columns, options)}
44   rescue DatabaseError
45     raise unless e
46   end
47   nil
48 end
alter_table(name, &block)

Alters the given table with the specified block. Example:

DB.alter_table :items do
  add_column :category, String, default: 'ruby'
  drop_column :category
  rename_column :cntr, :counter
  set_column_type :value, Float
  set_column_default :value, 4.2
  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 guide.

[show source]
   # File lib/sequel/database/schema_methods.rb
67 def alter_table(name, &block)
68   generator = alter_table_generator(&block)
69   remove_cached_schema(name)
70   apply_alter_table_generator(name, generator)
71   nil
72 end
alter_table_generator(&block)

Return a new Schema::AlterTableGenerator instance with the receiver as the database and the given block.

[show source]
   # File lib/sequel/database/schema_methods.rb
76 def alter_table_generator(&block)
77   alter_table_generator_class.new(self, &block)
78 end
create_join_table(hash, options=OPTS)

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.

The default table name this will create is the sorted version of the two hash values, joined by an underscore. So the following two method calls create the same table:

create_join_table(cat_id: :cats, dog_id: :dogs) # cats_dogs
create_join_table(dog_id: :dogs, cat_id: :cats) # cats_dogs

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.

[show source]
    # File lib/sequel/database/schema_methods.rb
119 def create_join_table(hash, options=OPTS)
120   keys = hash.keys.sort
121   create_table(join_table_name(hash, options), options) do
122     keys.each do |key|
123       v = hash[key]
124       unless v.is_a?(Hash)
125         v = {:table=>v}
126       end
127       v[:null] = false unless v.has_key?(:null)
128       foreign_key(key, v)
129     end
130     primary_key(keys) unless options[:no_primary_key]
131     index(keys.reverse, options[:index_options] || OPTS) unless options[:no_index]
132   end
133   nil
134 end
create_join_table!(hash, options=OPTS)

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

[show source]
    # File lib/sequel/database/schema_methods.rb
137 def create_join_table!(hash, options=OPTS)
138   drop_table?(join_table_name(hash, options))
139   create_join_table(hash, options)
140 end
create_join_table?(hash, options=OPTS)

Creates the join table unless it already exists.

[show source]
    # File lib/sequel/database/schema_methods.rb
143 def create_join_table?(hash, options=OPTS)
144   if supports_create_table_if_not_exists? && options[:no_index]
145     create_join_table(hash, options.merge(:if_not_exists=>true))
146   elsif !table_exists?(join_table_name(hash, options))
147     create_join_table(hash, options)
148   end
149 end
create_or_replace_view(name, source, options = OPTS)

Creates a view, replacing a view with the same name if one already exists.

DB.create_or_replace_view(:some_items, "SELECT * FROM items WHERE price < 100")
DB.create_or_replace_view(:some_items, DB[:items].where(category: 'ruby'))

For databases where replacing a view is not natively supported, support is emulated by dropping a view with the same name before creating the view.

[show source]
    # File lib/sequel/database/schema_methods.rb
256 def create_or_replace_view(name, source, options = OPTS)
257   if supports_create_or_replace_view? && !options[:materialized]
258     options = options.merge(:replace=>true)
259   else
260     swallow_database_error{drop_view(name, options)}
261   end
262 
263   create_view(name, source, options)
264   nil
265 end
create_table(name, options=OPTS, &block)

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

DB.create_table :posts do
  primary_key :id
  column :title, String
  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.

PostgreSQL specific options:

:on_commit

Either :preserve_rows (default), :drop or :delete_rows. Should only be specified when creating a temporary table.

:foreign

Create a foreign table. The value should be the name of the foreign server that was specified in CREATE SERVER.

:inherits

Inherit from a different table. An array can be specified to inherit from multiple tables.

:unlogged

Create the table as an unlogged table.

:options

The OPTIONS clause to use for foreign tables. Should be a hash where keys are option names and values are option values. Note that option names are unquoted, so you should not use untrusted keys.

:tablespace

The tablespace to use for the table.

SQLite specific options:

:strict

Create a STRICT table, which checks that the values for the columns are the correct type (similar to all other SQL databases). Note that when using this option, all column types used should be one of the following: int, integer, real, text, blob, and any. The any type is treated like a SQLite column in a non-strict table, allowing any type of data to be stored. This option is supported on SQLite 3.37.0+.

:using

Create a VIRTUAL table with the given USING clause. The value should be a string, as it is used directly in the SQL query.

:without_rowid

Create a WITHOUT ROWID table. Every row in SQLite has a special ‘rowid’ column, that uniquely identifies that row within the table. If this option is used, the ‘rowid’ column is omitted, which can sometimes provide some space and speed advantages. Note that you must then provide an explicit primary key when you create the table. This option is supported on SQLite 3.8.2+.

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

[show source]
    # File lib/sequel/database/schema_methods.rb
204 def create_table(name, options=OPTS, &block)
205   remove_cached_schema(name)
206   if sql = options[:as]
207     raise(Error, "can't provide both :as option and block to create_table") if block
208     create_table_as(name, sql, options)
209   else
210     generator = options[:generator] || create_table_generator(&block)
211     create_table_from_generator(name, generator, options)
212     create_table_indexes_from_generator(name, generator, options)
213   end
214   nil
215 end
create_table!(name, options=OPTS, &block)

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)
[show source]
    # File lib/sequel/database/schema_methods.rb
223 def create_table!(name, options=OPTS, &block)
224   drop_table?(name)
225   create_table(name, options, &block)
226 end
create_table?(name, options=OPTS, &block)

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
[show source]
    # File lib/sequel/database/schema_methods.rb
233 def create_table?(name, options=OPTS, &block)
234   options = options.dup
235   generator = options[:generator] ||= create_table_generator(&block)
236   if generator.indexes.empty? && supports_create_table_if_not_exists?
237     create_table(name, options.merge!(:if_not_exists=>true))
238   elsif !table_exists?(name)
239     create_table(name, options)
240   end
241 end
create_table_generator(&block)

Return a new Schema::CreateTableGenerator instance with the receiver as the database and the given block.

[show source]
    # File lib/sequel/database/schema_methods.rb
245 def create_table_generator(&block)
246   create_table_generator_class.new(self, &block)
247 end
create_view(name, source, options = OPTS)

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

DB.create_view(:cheap_items, "SELECT * FROM items WHERE price < 100")
# CREATE VIEW cheap_items AS
# SELECT * FROM items WHERE price < 100

DB.create_view(:ruby_items, DB[:items].where(category: 'ruby'))
# CREATE VIEW ruby_items AS
# SELECT * FROM items WHERE (category = 'ruby')

DB.create_view(:checked_items, DB[:items].where(:foo), check: true)
# CREATE VIEW checked_items AS
# SELECT * FROM items WHERE foo
# WITH CHECK OPTION

DB.create_view(:bar_items, DB[:items].select(:foo), columns: [:bar])
# CREATE VIEW bar_items (bar) AS
# SELECT foo FROM items

Options:

:columns

The column names to use for the view. If not given, automatically determined based on the input dataset.

:check

Adds a WITH CHECK OPTION clause, so that attempting to modify rows in the underlying table that would not be returned by the view is not allowed. This can be set to :local to use WITH LOCAL CHECK OPTION.

PostgreSQL/SQLite specific option:

:temp

Create a temporary view, automatically dropped on disconnect.

PostgreSQL specific options:

:materialized

Creates a materialized view, similar to a regular view, but backed by a physical table.

:recursive

Creates a recursive view. As columns must be specified for recursive views, you can also set them as the value of this option. Since a recursive view requires a union that isn’t in a subquery, if you are providing a Dataset as the source argument, if should probably call the union method with the all: true and from_self: false options.

:security_invoker

Set the security_invoker property on the view, making the access to the view use the current user’s permissions, instead of the view owner’s permissions.

:tablespace

The tablespace to use for materialized views.

[show source]
    # File lib/sequel/database/schema_methods.rb
310 def create_view(name, source, options = OPTS)
311   execute_ddl(create_view_sql(name, source, options))
312   remove_cached_schema(name)
313   nil
314 end
drop_column(table, *args)

Removes a column from the specified table:

DB.drop_column :items, :category

See alter_table.

[show source]
    # File lib/sequel/database/schema_methods.rb
321 def drop_column(table, *args)
322   alter_table(table) {drop_column(*args)}
323 end
drop_index(table, columns, options=OPTS)

Removes an index for the given table and column(s):

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

See alter_table.

[show source]
    # File lib/sequel/database/schema_methods.rb
331 def drop_index(table, columns, options=OPTS)
332   alter_table(table){drop_index(columns, options)}
333 end
drop_join_table(hash, options=OPTS)

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
[show source]
    # File lib/sequel/database/schema_methods.rb
340 def drop_join_table(hash, options=OPTS)
341   drop_table(join_table_name(hash, options), options)
342 end
drop_table(*names)

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)
[show source]
    # File lib/sequel/database/schema_methods.rb
349 def drop_table(*names)
350   options = names.last.is_a?(Hash) ? names.pop : OPTS 
351   names.each do |n|
352     execute_ddl(drop_table_sql(n, options))
353     remove_cached_schema(n)
354   end
355   nil
356 end
drop_table?(*names)

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
[show source]
    # File lib/sequel/database/schema_methods.rb
364 def drop_table?(*names)
365   options = names.last.is_a?(Hash) ? names.pop : OPTS
366   if supports_drop_table_if_exists?
367     options = options.merge(:if_exists=>true)
368     names.each do |name|
369       drop_table(name, options)
370     end
371   else
372     names.each do |name|
373       drop_table(name, options) if table_exists?(name)
374     end
375   end
376   nil
377 end
drop_view(*names)

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)
DB.drop_view(:cheap_items, :pricey_items, if_exists: true)

Options:

:cascade

Also drop objects depending on this view.

:if_exists

Do not raise an error if the view does not exist.

PostgreSQL specific options:

:materialized

Drop a materialized view.

[show source]
    # File lib/sequel/database/schema_methods.rb
392 def drop_view(*names)
393   options = names.last.is_a?(Hash) ? names.pop : OPTS
394   names.each do |n|
395     execute_ddl(drop_view_sql(n, options))
396     remove_cached_schema(n)
397   end
398   nil
399 end
rename_column(table, *args)

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.

[show source]
    # File lib/sequel/database/schema_methods.rb
418 def rename_column(table, *args)
419   alter_table(table) {rename_column(*args)}
420 end
rename_table(name, new_name)

Renames a table:

DB.tables #=> [:items]
DB.rename_table :items, :old_items
DB.tables #=> [:old_items]
[show source]
    # File lib/sequel/database/schema_methods.rb
406 def rename_table(name, new_name)
407   execute_ddl(rename_table_sql(name, new_name))
408   remove_cached_schema(name)
409   nil
410 end
set_column_default(table, *args)

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

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

See alter_table.

[show source]
    # File lib/sequel/database/schema_methods.rb
427 def set_column_default(table, *args)
428   alter_table(table) {set_column_default(*args)}
429 end
set_column_type(table, *args)

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

DB.set_column_type :items, :price, :float

See alter_table.

[show source]
    # File lib/sequel/database/schema_methods.rb
436 def set_column_type(table, *args)
437   alter_table(table) {set_column_type(*args)}
438 end

3 - Methods that create datasets

Public Instance methods

[](*args)

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"
[show source]
   # File lib/sequel/database/dataset.rb
21 def [](*args)
22   args.first.is_a?(String) ? fetch(*args) : from(*args)
23 end
dataset()

Returns a blank dataset for this database.

DB.dataset # SELECT *
DB.dataset.from(:items) # SELECT * FROM items
[show source]
   # File lib/sequel/database/dataset.rb
29 def dataset
30   @dataset_class.new(self)
31 end
fetch(sql, *args, &block)

Returns a dataset instance for the given SQL string:

ds = DB.fetch('SELECT * FROM items')

You can then call methods on the dataset to retrieve results:

ds.all
# SELECT * FROM items
# => [{:column=>value, ...}, ...]

If a block is given, it is passed to each on the resulting dataset to iterate over the records returned by the query:

DB.fetch('SELECT * FROM items'){|r| p r}
# {:column=>value, ...}
# ...

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

ds = DB.fetch('SELECT * FROM items WHERE name = ?', "my name")
ds.all
# SELECT * FROM items WHERE name = 'my name'

See caveats listed in Dataset#with_sql regarding datasets using custom SQL and the methods that can be called on them.

[show source]
   # File lib/sequel/database/dataset.rb
59 def fetch(sql, *args, &block)
60   ds = @default_dataset.with_sql(sql, *args)
61   ds.each(&block) if block
62   ds
63 end
from(*args, &block)

Returns a new dataset with the from method invoked. If a block is given, it acts as a virtual row block

DB.from(:items) # SELECT * FROM items
DB.from{schema[:table]} # SELECT * FROM schema.table
[show source]
   # File lib/sequel/database/dataset.rb
70 def from(*args, &block)
71   if block
72     @default_dataset.from(*args, &block)
73   elsif args.length == 1 && (table = args[0]).is_a?(Symbol)
74     @default_dataset.send(:cached_dataset, :"_from_#{table}_ds"){@default_dataset.from(table)}
75   else
76     @default_dataset.from(*args)
77   end
78 end
select(*args, &block)

Returns a new dataset with the select method invoked.

DB.select(1) # SELECT 1
DB.select{server_version.function} # SELECT server_version()
DB.select(:id).from(:items) # SELECT id FROM items
[show source]
   # File lib/sequel/database/dataset.rb
85 def select(*args, &block)
86   @default_dataset.select(*args, &block)
87 end

4 - Methods relating to adapters, connecting, disconnecting, and sharding

Constants

ADAPTERS = %w'ado amalgalite ibmdb jdbc mock mysql mysql2 odbc oracle postgres sqlanywhere sqlite tinytds trilogy'.map(&:to_sym)  

Array of supported database adapters

Attributes

pool [R]

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

Public Class methods

adapter_class(scheme)

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

[show source]
   # File lib/sequel/database/connecting.rb
16 def self.adapter_class(scheme)
17   scheme.is_a?(Class) ? scheme : load_adapter(scheme.to_sym)
18 end
adapter_scheme()

Returns the scheme symbol for the Database class.

[show source]
   # File lib/sequel/database/connecting.rb
21 def self.adapter_scheme
22   @scheme
23 end
connect(conn_string, opts = OPTS)

Connects to a database. See Sequel.connect.

[show source]
   # File lib/sequel/database/connecting.rb
26 def self.connect(conn_string, opts = OPTS)
27   case conn_string
28   when String
29     if conn_string.start_with?('jdbc:')
30       c = adapter_class(:jdbc)
31       opts = opts.merge(:orig_opts=>opts.dup)
32       opts = {:uri=>conn_string}.merge!(opts)
33     else
34       uri = URI.parse(conn_string)
35       scheme = uri.scheme
36       c = adapter_class(scheme)
37       opts = c.send(:options_from_uri, uri).merge!(opts).merge!(:orig_opts=>opts.dup, :uri=>conn_string, :adapter=>scheme)
38     end
39   when Hash
40     opts = conn_string.merge(opts)
41     opts = opts.merge(:orig_opts=>opts.dup)
42     c = adapter_class(opts[:adapter_class] || opts[:adapter] || opts['adapter'])
43   else
44     raise Error, "Sequel::Database.connect takes either a Hash or a String, given: #{conn_string.inspect}"
45   end
46 
47   opts = opts.inject({}) do |m, (k,v)|
48     k = :user if k.to_s == 'username'
49     m[k.to_sym] = v
50     m
51   end
52 
53   begin
54     db = c.new(opts)
55     if defined?(yield)
56       return yield(db)
57     end
58   ensure
59     if defined?(yield)
60       db.disconnect if db
61       Sequel.synchronize{::Sequel::DATABASES.delete(db)}
62     end
63   end
64   db
65 end
load_adapter(scheme, opts=OPTS)

Load the adapter from the file system. Raises Sequel::AdapterNotFound if the adapter cannot be loaded, or if the adapter isn’t registered correctly after being loaded. Options:

:map

The Hash in which to look for an already loaded adapter (defaults to ADAPTER_MAP).

:subdir

The subdirectory of sequel/adapters to look in, only to be used for loading subadapters.

[show source]
   # File lib/sequel/database/connecting.rb
73 def self.load_adapter(scheme, opts=OPTS)
74   map = opts[:map] || ADAPTER_MAP
75   if subdir = opts[:subdir]
76     file = "#{subdir}/#{scheme}"
77   else
78     file = scheme
79   end
80   
81   unless obj = Sequel.synchronize{map[scheme]}
82     # attempt to load the adapter file
83     begin
84       require "sequel/adapters/#{file}"
85     rescue LoadError => e
86       # If subadapter file doesn't exist, just return,
87       # using the main adapter class without database customizations.
88       return if subdir
89       raise Sequel.convert_exception_class(e, AdapterNotFound)
90     end
91     
92     # make sure we actually loaded the adapter
93     unless obj = Sequel.synchronize{map[scheme]}
94       raise AdapterNotFound, "Could not load #{file} adapter: adapter class not registered in ADAPTER_MAP"
95     end
96   end
97 
98   obj
99 end
set_shared_adapter_scheme(scheme, mod)

Sets the given module as the shared adapter module for the given scheme. Used to register shared adapters for use by the mock adapter. Example:

# in file sequel/adapters/shared/mydb.rb
module Sequel::MyDB
  Sequel::Database.set_shared_adapter_scheme :mydb, self

  def self.mock_adapter_setup(db)
    # ...
  end

  module DatabaseMethods
    # ...
  end

  module DatasetMethods
    # ...
  end
end

would allow the mock adapter to return a Database instance that supports the MyDB syntax via:

Sequel.connect('mock://mydb')
[show source]
    # File lib/sequel/database/connecting.rb
143 def self.set_shared_adapter_scheme(scheme, mod)
144   Sequel.synchronize{SHARED_ADAPTER_MAP[scheme] = mod}
145 end

Public Instance methods

adapter_scheme()

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
[show source]
    # File lib/sequel/database/connecting.rb
158 def adapter_scheme
159   self.class.adapter_scheme
160 end
add_servers(servers)

Dynamically add new servers or modify server options at runtime. Also adds new servers to the connection pool. Only usable when using a sharded connection pool.

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"})
[show source]
    # File lib/sequel/database/connecting.rb
170 def add_servers(servers)
171   unless sharded?
172     raise Error, "cannot call Database#add_servers on a Database instance that does not use a sharded connection pool"
173   end
174 
175   h = @opts[:servers]
176   Sequel.synchronize{h.merge!(servers)}
177   @pool.add_servers(servers.keys)
178 end
database_type()

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.

Sequel.connect('jdbc:postgres://...').database_type
# => :postgres
[show source]
    # File lib/sequel/database/connecting.rb
189 def database_type
190   adapter_scheme
191 end
disconnect(opts = OPTS)

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

:server

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(server: :server1) # Single server
DB.disconnect(server: [:server1, :server2]) # Multiple servers
[show source]
    # File lib/sequel/database/connecting.rb
203 def disconnect(opts = OPTS)
204   pool.disconnect(opts)
205 end
disconnect_connection(conn)

Should only be called by the connection pool code to disconnect a connection. By default, calls the close method on the connection object, since most adapters use that, but should be overwritten on other adapters.

[show source]
    # File lib/sequel/database/connecting.rb
210 def disconnect_connection(conn)
211   conn.close
212 end
new_connection(server)

Connect to the given server/shard. Handles database-generic post-connection setup not handled by connect, using the :after_connect and :connect_sqls options.

[show source]
    # File lib/sequel/database/connecting.rb
244 def new_connection(server)
245   conn = connect(server)
246   opts = server_opts(server)
247 
248   if ac = opts[:after_connect]
249     if ac.arity == 2
250       ac.call(conn, server)
251     else
252       ac.call(conn)
253     end
254   end
255 
256   if cs = opts[:connect_sqls]
257     cs.each do |sql|
258       log_connection_execute(conn, sql)
259     end
260   end
261 
262   conn
263 end
remove_servers(*servers)

Dynamically remove existing servers from the connection pool. Only usable when using a sharded connection pool

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)
[show source]
    # File lib/sequel/database/connecting.rb
223 def remove_servers(*servers)
224   unless sharded?
225     raise Error, "cannot call Database#remove_servers on a Database instance that does not use a sharded connection pool"
226   end
227 
228   h = @opts[:servers]
229   servers.flatten.each{|s| Sequel.synchronize{h.delete(s)}}
230   @pool.remove_servers(servers)
231 end
servers()

An array of servers/shards for this Database object.

DB.servers # Unsharded: => [:default]
DB.servers # Sharded:   => [:default, :server1, :server2]
[show source]
    # File lib/sequel/database/connecting.rb
237 def servers
238   pool.servers
239 end
single_threaded?()

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

[show source]
    # File lib/sequel/database/connecting.rb
266 def single_threaded?
267   @single_threaded
268 end
synchronize(server=nil, &block)

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
[show source]
    # File lib/sequel/database/connecting.rb
282 def synchronize(server=nil, &block)
283   @pool.hold(server || :default, &block)
284 end
test_connection(server=nil)

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.

[show source]
    # File lib/sequel/database/connecting.rb
290 def test_connection(server=nil)
291   synchronize(server){|conn|}
292   true
293 end
valid_connection?(conn)

Check whether the given connection is currently valid, by running a query against it. If the query fails, the connection should probably be removed from the connection pool.

[show source]
    # File lib/sequel/database/connecting.rb
299 def valid_connection?(conn)
300   sql = valid_connection_sql
301   begin
302     log_connection_execute(conn, sql)
303   rescue Sequel::DatabaseError, *database_error_classes
304     false
305   else
306     true
307   end
308 end

5 - Methods that set defaults for created datasets

Attributes

dataset_class [R]

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

Public Instance methods

dataset_class=(c)

If the database has any dataset modules associated with it, use a subclass of the given class that includes the modules as the dataset class.

[show source]
   # File lib/sequel/database/dataset_defaults.rb
18 def dataset_class=(c)
19   unless @dataset_modules.empty?
20     c = Class.new(c)
21     @dataset_modules.each{|m| c.send(:include, m)}
22   end
23   @dataset_class = c
24   reset_default_dataset
25 end
extend_datasets(mod=nil, &block)

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.

If a block is given, a Dataset::DatasetModule instance is created, allowing for the easy creation of named dataset methods that will do caching.

Examples:

# Introspect 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

# Add some named dataset methods
DB.extend_datasets do
  order :by_id, :id
  select :with_id_and_name, :id, :name
  where :active, :active
end

DB[:table].active.with_id_and_name.by_id
# SELECT id, name FROM table WHERE active ORDER BY id
[show source]
   # File lib/sequel/database/dataset_defaults.rb
62 def extend_datasets(mod=nil, &block)
63   raise(Error, "must provide either mod or block, not both") if mod && block
64   mod = Dataset::DatasetModule.new(&block) if block
65   if @dataset_modules.empty?
66    @dataset_modules = [mod]
67    @dataset_class = Class.new(@dataset_class)
68   else
69    @dataset_modules << mod
70   end
71   @dataset_class.send(:include, mod)
72   reset_default_dataset
73 end

6 - Methods relating to logging

Attributes

log_connection_info [RW]

Whether to include information about the connection in use when logging queries.

log_warn_duration [RW]

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

loggers [RW]

Array of SQL loggers to use for this database.

sql_log_level [RW]

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.

Public Instance methods

log_connection_yield(sql, conn, args=nil)

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.

[show source]
   # File lib/sequel/database/logging.rb
37 def log_connection_yield(sql, conn, args=nil)
38   return yield if skip_logging?
39   sql = "#{connection_info(conn) if conn && log_connection_info}#{sql}#{"; #{args.inspect}" if args}"
40   timer = Sequel.start_timer
41 
42   begin
43     yield
44   rescue => e
45     log_exception(e, sql)
46     raise
47   ensure
48     log_duration(Sequel.elapsed_seconds_since(timer), sql) unless e
49   end
50 end
log_exception(exception, message)

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

[show source]
   # File lib/sequel/database/logging.rb
26 def log_exception(exception, message)
27   log_each(:error, "#{exception.class}: #{exception.message.strip if exception.message}: #{message}")
28 end
log_info(message, args=nil)

Log a message at level info to all loggers.

[show source]
   # File lib/sequel/database/logging.rb
31 def log_info(message, args=nil)
32   log_each(:info, args ? "#{message}; #{args.inspect}" : message)
33 end
logger=(logger)

Remove any existing loggers and just use the given logger:

DB.logger = Logger.new($stdout)
[show source]
   # File lib/sequel/database/logging.rb
55 def logger=(logger)
56   @loggers = Array(logger)
57 end

7 - Miscellaneous methods

Constants

CHECK_CONSTRAINT_SQLSTATES = %w'23513 23514'.freeze.each(&:freeze)  
DEFAULT_DATABASE_ERROR_REGEXPS = {}.freeze  

Empty exception regexp to class map, used by default if Sequel doesn’t have specific support for the database in use.

DEFAULT_STRING_COLUMN_SIZE = 255  

The general default size for string columns for all Sequel::Database instances.

EXTENSIONS = {}  

Hash of extension name symbols to callable objects to load the extension into the Database object (usually by extending it with a module defined in the extension).

FOREIGN_KEY_CONSTRAINT_SQLSTATES = %w'23503 23506 23504'.freeze.each(&:freeze)  
NOT_NULL_CONSTRAINT_SQLSTATES = %w'23502'.freeze.each(&:freeze)  
SCHEMA_TYPE_CLASSES = {:string=>String, :integer=>Integer, :date=>Date, :datetime=>[Time, DateTime].freeze, :time=>Sequel::SQLTime, :boolean=>[TrueClass, FalseClass].freeze, :float=>Float, :decimal=>BigDecimal, :blob=>Sequel::SQL::Blob}.freeze  

Mapping of schema type symbols to class or arrays of classes for that symbol.

SERIALIZATION_CONSTRAINT_SQLSTATES = %w'40001'.freeze.each(&:freeze)  
UNIQUE_CONSTRAINT_SQLSTATES = %w'23505'.freeze.each(&:freeze)  

Attributes

check_string_typecast_bytesize [RW]

Whether to check the bytesize of strings before typecasting (to avoid typecasting strings that would be too long for the given type), true by default. Strings that are too long will raise a typecasting error.

default_string_column_size [RW]

The specific default size of string columns for this Sequel::Database, usually 255 by default.

opts [R]

The options hash for this database

timezone [W]

Set the timezone to use for this database, overridding Sequel.database_timezone.

Public Class methods

after_initialize(&block)

Register a hook that will be run when a new Database is instantiated. It is called with the new database handle.

[show source]
   # File lib/sequel/database/misc.rb
39 def self.after_initialize(&block)
40   raise Error, "must provide block to after_initialize" unless block
41   Sequel.synchronize do
42     previous = @initialize_hook
43     @initialize_hook = proc do |db|
44       previous.call(db)
45       block.call(db)
46     end
47   end
48 end
extension(*extensions)

Apply an extension to all Database objects created in the future.

[show source]
   # File lib/sequel/database/misc.rb
51 def self.extension(*extensions)
52   after_initialize{|db| db.extension(*extensions)}
53 end
new(opts = OPTS)

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

Accepts the following options:

:after_connect

A callable object called after each new connection is made, with the connection object (and server argument if the callable accepts 2 arguments), useful for customizations that you want to apply to all connections.

:before_preconnect

Callable that runs after extensions from :preconnect_extensions are loaded, but before any connections are created.

:cache_schema

Whether schema should be cached for this Database instance

:check_string_typecast_bytesize

Whether to check the bytesize of strings before typecasting.

:connect_sqls

An array of sql strings to execute on each new connection, after :after_connect runs.

:connect_opts_proc

Callable object for modifying options hash used when connecting, designed for cases where the option values (e.g. password) are automatically rotated on a regular basis without involvement from the application using Sequel.

:default_string_column_size

The default size of string columns, 255 by default.

:extensions

Extensions to load into this Database instance. Can be a symbol, array of symbols, or string with extensions separated by columns. These extensions are loaded after connections are made by the :preconnect option.

:keep_reference

Whether to keep a reference to this instance in Sequel::DATABASES, true by default.

:logger

A specific logger to use.

:loggers

An array of loggers to use.

:log_connection_info

Whether connection information should be logged when logging queries.

:log_warn_duration

The number of elapsed seconds after which queries should be logged at warn level.

:name

A name to use for the Database object, displayed in PoolTimeout.

:preconnect

Automatically create the maximum number of connections, so that they don’t need to be created as needed. This is useful when connecting takes a long time and you want to avoid possible latency during runtime. Set to :concurrently to create the connections in separate threads. Otherwise they’ll be created sequentially.

:preconnect_extensions

Similar to the :extensions option, but loads the extensions before the connections are made by the :preconnect option.

: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.

For sharded connection pools, :after_connect and :connect_sqls can be specified per-shard.

All options given are also passed to the connection pool. Additional options respected by the connection pool are :max_connections, :pool_timeout, :servers, and :servers_hash. See the connection pool documentation for details.

[show source]
    # File lib/sequel/database/misc.rb
154 def initialize(opts = OPTS)
155   @opts ||= opts
156   @opts = connection_pool_default_options.merge(@opts)
157   @loggers = Array(@opts[:logger]) + Array(@opts[:loggers])
158   @opts[:servers] = {} if @opts[:servers].is_a?(String)
159   @sharded = !!@opts[:servers]
160   @opts[:adapter_class] = self.class
161   @opts[:single_threaded] = @single_threaded = typecast_value_boolean(@opts.fetch(:single_threaded, Sequel.single_threaded))
162   @default_string_column_size = @opts[:default_string_column_size] || DEFAULT_STRING_COLUMN_SIZE
163   @check_string_typecast_bytesize = typecast_value_boolean(@opts.fetch(:check_string_typecast_bytesize, true))
164 
165   @schemas = {}
166   @prepared_statements = {}
167   @transactions = {}
168   @transactions.compare_by_identity
169   @symbol_literal_cache = {}
170 
171   @timezone = nil
172 
173   @dataset_class = dataset_class_default
174   @cache_schema = typecast_value_boolean(@opts.fetch(:cache_schema, true))
175   @dataset_modules = []
176   @loaded_extensions = []
177   @schema_type_classes = SCHEMA_TYPE_CLASSES.dup
178 
179   self.sql_log_level = @opts[:sql_log_level] ? @opts[:sql_log_level].to_sym : :info
180   self.log_warn_duration = @opts[:log_warn_duration]
181   self.log_connection_info = typecast_value_boolean(@opts[:log_connection_info])
182 
183   @pool = ConnectionPool.get_pool(self, @opts)
184 
185   reset_default_dataset
186   adapter_initialize
187 
188   keep_reference = typecast_value_boolean(@opts[:keep_reference]) != false
189   begin
190     Sequel.synchronize{::Sequel::DATABASES.push(self)} if keep_reference
191     Sequel::Database.run_after_initialize(self)
192 
193     initialize_load_extensions(:preconnect_extensions)
194 
195     if before_preconnect = @opts[:before_preconnect]
196       before_preconnect.call(self)
197     end
198 
199     if typecast_value_boolean(@opts[:preconnect]) && @pool.respond_to?(:preconnect, true)
200       concurrent = typecast_value_string(@opts[:preconnect]) == "concurrently"
201       @pool.send(:preconnect, concurrent)
202     end
203 
204     initialize_load_extensions(:extensions)
205     test_connection if typecast_value_boolean(@opts.fetch(:test, true)) && respond_to?(:connect, true)
206   rescue
207     Sequel.synchronize{::Sequel::DATABASES.delete(self)} if keep_reference
208     raise
209   end
210 end
register_extension(ext, mod=nil, &block)

Register an extension callback for Database objects. ext should be the extension name symbol, and mod should either be a Module that the database is extended with, or a callable object called with the database object. If mod is not provided, a block can be provided and is treated as the mod object.

[show source]
   # File lib/sequel/database/misc.rb
60 def self.register_extension(ext, mod=nil, &block)
61   if mod
62     raise(Error, "cannot provide both mod and block to Database.register_extension") if block
63     if mod.is_a?(Module)
64       block = proc{|db| db.extend(mod)}
65     else
66       block = mod
67     end
68   end
69   Sequel.synchronize{EXTENSIONS[ext] = block}
70 end
run_after_initialize(instance)

Run the after_initialize hook for the given instance.

[show source]
   # File lib/sequel/database/misc.rb
73 def self.run_after_initialize(instance)
74   @initialize_hook.call(instance)
75 end

Public Instance methods

cast_type_literal(type)

Cast the given type to a literal type

DB.cast_type_literal(Float) # double precision
DB.cast_type_literal(:foo)  # foo
[show source]
    # File lib/sequel/database/misc.rb
239 def cast_type_literal(type)
240   type_literal(:type=>type)
241 end
extension(*exts)

Load an extension into the receiver. In addition to requiring the extension file, this also modifies the database to work with the extension (usually extending it with a module defined in the extension file). If no related extension file exists or the extension does not have specific support for Database objects, an Error will be raised. Returns self.

[show source]
    # File lib/sequel/database/misc.rb
248 def extension(*exts)
249   exts.each do |ext|
250     unless pr = Sequel.synchronize{EXTENSIONS[ext]}
251       Sequel.extension(ext)
252       pr = Sequel.synchronize{EXTENSIONS[ext]}
253     end
254 
255     if pr
256       if Sequel.synchronize{@loaded_extensions.include?(ext) ? false : (@loaded_extensions << ext)}
257         pr.call(self)
258       end
259     else
260       raise(Error, "Extension #{ext} does not have specific support handling individual databases (try: Sequel.extension #{ext.inspect})")
261     end
262   end
263   self
264 end
freeze()

Freeze internal data structures for the Database instance.

[show source]
    # File lib/sequel/database/misc.rb
213 def freeze
214   valid_connection_sql
215   metadata_dataset
216   @opts.freeze
217   @loggers.freeze
218   @pool.freeze
219   @dataset_class.freeze
220   @dataset_modules.freeze
221   @schema_type_classes.freeze
222   @loaded_extensions.freeze
223   metadata_dataset
224   super
225 end
from_application_timestamp(v)

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.

[show source]
    # File lib/sequel/database/misc.rb
269 def from_application_timestamp(v)
270   Sequel.convert_output_timestamp(v, timezone)
271 end
inspect()

Returns a string representation of the Database object, including the database type, host, database, and user, if present.

[show source]
    # File lib/sequel/database/misc.rb
275 def inspect
276   s = String.new
277   s << "#<#{self.class}"
278   s << " database_type=#{database_type}" if database_type && database_type != adapter_scheme
279 
280   keys = [:host, :database, :user]
281   opts = self.opts
282   if !keys.any?{|k| opts[k]} && opts[:uri]
283     opts = self.class.send(:options_from_uri, URI.parse(opts[:uri]))
284   end
285 
286   keys.each do |key|
287     val = opts[key]
288     if val && val != ''
289       s << " #{key}=#{val}"
290     end
291   end
292 
293   s << ">"
294 end
literal(v)

Proxy the literal call to the dataset.

DB.literal(1)   # 1
DB.literal(:a)  # "a" # or `a`, [a], or a, depending on identifier quoting
DB.literal("a") # 'a'
[show source]
    # File lib/sequel/database/misc.rb
301 def literal(v)
302   schema_utility_dataset.literal(v)
303 end
literal_symbol(sym)

Return the literalized version of the symbol if cached, or nil if it is not cached.

[show source]
    # File lib/sequel/database/misc.rb
307 def literal_symbol(sym)
308   Sequel.synchronize{@symbol_literal_cache[sym]}
309 end
literal_symbol_set(sym, lit)

Set the cached value of the literal symbol.

[show source]
    # File lib/sequel/database/misc.rb
312 def literal_symbol_set(sym, lit)
313   Sequel.synchronize{@symbol_literal_cache[sym] = lit}
314 end
prepared_statement(name)

Synchronize access to the prepared statements cache.

[show source]
    # File lib/sequel/database/misc.rb
317 def prepared_statement(name)
318   Sequel.synchronize{prepared_statements[name]}
319 end
quote_identifier(v)

Proxy the quote_identifier method to the dataset, useful for quoting unqualified identifiers for use outside of datasets.

[show source]
    # File lib/sequel/database/misc.rb
324 def quote_identifier(v)
325   schema_utility_dataset.quote_identifier(v)
326 end
schema_type_class(type)

Return ruby class or array of classes for the given type symbol.

[show source]
    # File lib/sequel/database/misc.rb
329 def schema_type_class(type)
330   @schema_type_classes[type]
331 end
serial_primary_key_options()

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

[show source]
    # File lib/sequel/database/misc.rb
334 def serial_primary_key_options
335   {:primary_key => true, :type => Integer, :auto_increment => true}
336 end
set_prepared_statement(name, ps)

Cache the prepared statement object at the given name.

[show source]
    # File lib/sequel/database/misc.rb
339 def set_prepared_statement(name, ps)
340   Sequel.synchronize{prepared_statements[name] = ps}
341 end
sharded?()

Whether this database instance uses multiple servers, either for sharding or for primary/replica configurations.

[show source]
    # File lib/sequel/database/misc.rb
345 def sharded?
346   @sharded
347 end
timezone()

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

[show source]
    # File lib/sequel/database/misc.rb
350 def timezone
351   @timezone || Sequel.database_timezone
352 end
to_application_timestamp(v)

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.

[show source]
    # File lib/sequel/database/misc.rb
357 def to_application_timestamp(v)
358   Sequel.convert_timestamp(v, timezone)
359 end
typecast_value(column_type, value)

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.

[show source]
    # File lib/sequel/database/misc.rb
366 def typecast_value(column_type, value)
367   return nil if value.nil?
368   meth = "typecast_value_#{column_type}"
369   begin
370     # Allow calling private methods as per-type typecasting methods are private
371     respond_to?(meth, true) ? send(meth, value) : value
372   rescue ArgumentError, TypeError => e
373     raise Sequel.convert_exception_class(e, InvalidValue)
374   end
375 end
uri()

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

[show source]
    # File lib/sequel/database/misc.rb
379 def uri
380   opts[:uri]
381 end
url()

Explicit alias of uri for easier subclassing.

[show source]
    # File lib/sequel/database/misc.rb
384 def url
385   uri
386 end

8 - Methods related to database transactions

Constants

TRANSACTION_ISOLATION_LEVELS = {:uncommitted=>'READ UNCOMMITTED'.freeze, :committed=>'READ COMMITTED'.freeze, :repeatable=>'REPEATABLE READ'.freeze, :serializable=>'SERIALIZABLE'.freeze}.freeze  

Attributes

transaction_isolation_level [RW]

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.

Public Instance methods

after_commit(opts=OPTS, &block)

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:

:savepoint

If currently inside a savepoint, only run this hook on transaction commit if all enclosing savepoints have been released.

:server

The server/shard to use.

[show source]
   # File lib/sequel/database/transactions.rb
31 def after_commit(opts=OPTS, &block)
32   raise Error, "must provide block to after_commit" unless block
33   synchronize(opts[:server]) do |conn|
34     if h = _trans(conn)
35       raise Error, "cannot call after_commit in a prepared transaction" if h[:prepare]
36       if opts[:savepoint] && in_savepoint?(conn)
37         add_savepoint_hook(conn, :after_commit, block)
38       else
39         add_transaction_hook(conn, :after_commit, block)
40       end
41     else
42       yield
43     end
44   end
45 end
after_rollback(opts=OPTS, &block)

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:

:savepoint

If currently inside a savepoint, run this hook immediately when any enclosing savepoint is rolled back, which may be before the transaction commits or rollsback.

:server

The server/shard to use.

[show source]
   # File lib/sequel/database/transactions.rb
55 def after_rollback(opts=OPTS, &block)
56   raise Error, "must provide block to after_rollback" unless block
57   synchronize(opts[:server]) do |conn|
58     if h = _trans(conn)
59       raise Error, "cannot call after_rollback in a prepared transaction" if h[:prepare]
60       if opts[:savepoint] && in_savepoint?(conn)
61         add_savepoint_hook(conn, :after_rollback, block)
62       else
63         add_transaction_hook(conn, :after_rollback, block)
64       end
65     end
66   end
67 end
in_transaction?(opts=OPTS)

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

[show source]
    # File lib/sequel/database/transactions.rb
113 def in_transaction?(opts=OPTS)
114   synchronize(opts[:server]){|conn| !!_trans(conn)}
115 end
rollback_checker(opts=OPTS)

Returns a proc that you can call to check if the transaction has been rolled back. The proc will return nil if the transaction is still in progress, true if the transaction was rolled back, and false if it was committed. Raises an Error if called outside a transaction. Respects the :server option for selecting a shard.

[show source]
    # File lib/sequel/database/transactions.rb
123 def rollback_checker(opts=OPTS)
124   synchronize(opts[:server]) do |conn|
125     raise Error, "not in a transaction" unless t = _trans(conn)
126     t[:rollback_checker] ||= proc{Sequel.synchronize{t[:rolled_back]}}
127   end
128 end
rollback_on_exit(opts=OPTS)

When exiting the transaction block through methods other than an exception (e.g. normal exit, non-local return, or throw), set the current transaction to rollback instead of committing. This is designed for use in cases where you want to preform a non-local return but also want to rollback instead of committing. Options:

:cancel

Cancel the current rollback_on_exit setting, so exiting will commit instead of rolling back.

:savepoint

Rollback only the current savepoint if inside a savepoint. Can also be an positive integer value to rollback that number of enclosing savepoints, up to and including the transaction itself. If the database does not support savepoints, this option is ignored and the entire transaction is affected.

:server

The server/shard the transaction is being executed on.

[show source]
    # File lib/sequel/database/transactions.rb
 83 def rollback_on_exit(opts=OPTS)
 84   synchronize(opts[:server]) do |conn|
 85     raise Error, "Cannot call Sequel:: Database#rollback_on_exit unless inside a transaction" unless h = _trans(conn)
 86     rollback = !opts[:cancel]
 87 
 88     if supports_savepoints?
 89       savepoints = h[:savepoints]
 90 
 91       if level = opts[:savepoint]
 92         level = 1 if level == true
 93         raise Error, "invalid :savepoint option to Database#rollback_on_exit: #{level.inspect}" unless level.is_a?(Integer)
 94         raise Error, "cannot pass nonpositive integer (#{level.inspect}) as :savepoint option to Database#rollback_on_exit" if level < 1
 95         level.times do |i|
 96           break unless savepoint = savepoints[-1 - i]
 97           savepoint[:rollback_on_exit] = rollback
 98         end
 99       else
100         savepoints[0][:rollback_on_exit] = rollback
101       end
102     else
103       h[:rollback_on_exit] = rollback
104     end
105   end
106 
107   nil
108 end
transaction(opts=OPTS, &block)

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 tables do not support transactions.

The following general options are respected:

:auto_savepoint

Automatically use a savepoint for Database#transaction calls inside this transaction block.

: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.

:num_retries

The number of times to retry if the :retry_on option is used. The default is 5 times. Can be set to nil to retry indefinitely, but that is not recommended.

:before_retry

Proc to execute before retrying if the :retry_on option is used. Called with two arguments: the number of retry attempts (counting the current one) and the error the last attempt failed with.

:prepare

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

:retry_on

An exception class or array of exception classes for which to automatically retry the transaction. Can only be set if not inside an existing transaction. Note that this should not be used unless the entire transaction block is idempotent, as otherwise it can cause non-idempotent behavior to execute multiple times.

:rollback

Can be 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. Set to :default, :read_only, or whatever symbol you used in the connect string when naming your servers.

: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. If the surrounding transaction uses :auto_savepoint, you can set this to false to not use a savepoint. If the value given for this option is :only, it will only create a savepoint if it is inside a transaction.

:skip_transaction

If set, do not actually open a transaction or savepoint, just checkout a connection and yield it.

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+).

[show source]
    # File lib/sequel/database/transactions.rb
179 def transaction(opts=OPTS, &block)
180   opts = Hash[opts]
181   if retry_on = opts[:retry_on]
182     tot_retries = opts.fetch(:num_retries, 5)
183     num_retries = 0
184     begin
185       opts[:retry_on] = nil
186       opts[:retrying] = true
187       transaction(opts, &block)
188     rescue *retry_on => e
189       num_retries += 1
190       if tot_retries.nil? || num_retries <= tot_retries
191         opts[:before_retry].call(num_retries, e) if opts[:before_retry]
192         retry
193       end
194       raise
195     end
196   else
197     synchronize(opts[:server]) do |conn|
198       if opts[:skip_transaction]
199         return yield(conn)
200       end
201 
202       if opts[:savepoint] == :only
203         if supports_savepoints?
204           if _trans(conn)
205             opts[:savepoint] = true
206           else
207             return yield(conn)
208           end
209         else
210           opts[:savepoint] = false
211         end
212       end
213 
214       if opts[:savepoint] && !supports_savepoints?
215         raise Sequel::InvalidOperation, "savepoints not supported on #{database_type}"
216       end
217 
218       if already_in_transaction?(conn, opts)
219         if opts[:rollback] == :always && !opts.has_key?(:savepoint)
220           if supports_savepoints? 
221             opts[:savepoint] = true
222           else
223             raise Sequel::Error, "cannot set :rollback=>:always transaction option if already inside a transaction"
224           end
225         end
226 
227         if opts[:savepoint] != false && (stack = _trans(conn)[:savepoints]) && stack.last[:auto_savepoint]
228           opts[:savepoint] = true
229         end
230 
231         unless opts[:savepoint]
232           if opts[:retrying]
233             raise Sequel::Error, "cannot set :retry_on options if you are already inside a transaction"
234           end
235           return yield(conn)
236         end
237       end
238 
239       _transaction(conn, opts, &block)
240     end
241   end
242 end

9 - Methods that describe what the database supports

Public Instance methods

global_index_namespace?()

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

[show source]
   # File lib/sequel/database/features.rb
13 def global_index_namespace?
14   true
15 end
supports_create_table_if_not_exists?()

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

[show source]
   # File lib/sequel/database/features.rb
19 def supports_create_table_if_not_exists?
20   false
21 end
supports_deferrable_constraints?()

Whether the database supports deferrable constraints, false by default as few databases do.

[show source]
   # File lib/sequel/database/features.rb
25 def supports_deferrable_constraints?
26   false
27 end
supports_deferrable_foreign_key_constraints?()

Whether the database supports deferrable foreign key constraints, false by default as few databases do.

[show source]
   # File lib/sequel/database/features.rb
31 def supports_deferrable_foreign_key_constraints?
32   supports_deferrable_constraints?
33 end
supports_drop_table_if_exists?()

Whether the database supports DROP TABLE IF EXISTS syntax, false by default.

[show source]
   # File lib/sequel/database/features.rb
37 def supports_drop_table_if_exists?
38   supports_create_table_if_not_exists?
39 end
supports_foreign_key_parsing?()

Whether the database supports Database#foreign_key_list for parsing foreign keys.

[show source]
   # File lib/sequel/database/features.rb
43 def supports_foreign_key_parsing?
44   respond_to?(:foreign_key_list)
45 end
supports_index_parsing?()

Whether the database supports Database#indexes for parsing indexes.

[show source]
   # File lib/sequel/database/features.rb
48 def supports_index_parsing?
49   respond_to?(:indexes)
50 end
supports_partial_indexes?()

Whether the database supports partial indexes (indexes on a subset of a table), false by default.

[show source]
   # File lib/sequel/database/features.rb
54 def supports_partial_indexes?
55   false
56 end
supports_prepared_transactions?()

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

[show source]
   # File lib/sequel/database/features.rb
60 def supports_prepared_transactions?
61   false
62 end
supports_savepoints?()

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

[show source]
   # File lib/sequel/database/features.rb
65 def supports_savepoints?
66   false
67 end
supports_savepoints_in_prepared_transactions?()

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

[show source]
   # File lib/sequel/database/features.rb
71 def supports_savepoints_in_prepared_transactions?
72   supports_prepared_transactions? && supports_savepoints?
73 end
supports_schema_parsing?()

Whether the database supports schema parsing via Database#schema.

[show source]
   # File lib/sequel/database/features.rb
76 def supports_schema_parsing?
77   respond_to?(:schema_parse_table, true)
78 end
supports_table_listing?()

Whether the database supports Database#tables for getting list of tables.

[show source]
   # File lib/sequel/database/features.rb
81 def supports_table_listing?
82   respond_to?(:tables)
83 end
supports_transaction_isolation_levels?()

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

[show source]
   # File lib/sequel/database/features.rb
91 def supports_transaction_isolation_levels?
92   false
93 end
supports_transactional_ddl?()

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

[show source]
   # File lib/sequel/database/features.rb
96 def supports_transactional_ddl?
97   false
98 end
supports_view_listing?()

Whether the database supports Database#views for getting list of views.

[show source]
   # File lib/sequel/database/features.rb
86 def supports_view_listing?
87   respond_to?(:views)
88 end
supports_views_with_check_option?()

Whether CREATE VIEW … WITH CHECK OPTION is supported, false by default.

[show source]
    # File lib/sequel/database/features.rb
101 def supports_views_with_check_option?
102   !!view_with_check_option_support
103 end
supports_views_with_local_check_option?()

Whether CREATE VIEW … WITH LOCAL CHECK OPTION is supported, false by default.

[show source]
    # File lib/sequel/database/features.rb
106 def supports_views_with_local_check_option?
107   view_with_check_option_support == :local
108 end