Class Sequel::Database
In: lib/sequel/database/query.rb
lib/sequel/database/transactions.rb
lib/sequel/database/schema_methods.rb
lib/sequel/database/logging.rb
lib/sequel/database/misc.rb
lib/sequel/database/connecting.rb
lib/sequel/database/dataset.rb
lib/sequel/database/features.rb
lib/sequel/database/dataset_defaults.rb
lib/sequel/adapters/mysql2.rb
lib/sequel/adapters/mysql.rb
lib/sequel/database.rb
Parent: 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

<<   []   adapter_class   adapter_scheme   adapter_scheme   add_column   add_index   add_servers   after_commit   after_initialize   after_rollback   alter_table   alter_table_generator   call   cast_type_literal   connect   connect   connect   convert_invalid_date_time=   convert_tinyint_to_bool=   create_join_table   create_join_table!   create_join_table?   create_or_replace_view   create_table   create_table!   create_table?   create_table_generator   create_view   database_type   dataset   dataset_class=   disconnect   disconnect_connection   disconnect_connection   drop_column   drop_index   drop_join_table   drop_table   drop_table?   drop_view   execute_ddl   execute_dui   execute_dui   execute_dui   execute_insert   execute_insert   execute_insert   extend_datasets   extension   extension   fetch   freeze   freeze   freeze   from   from_application_timestamp   get   global_index_namespace?   in_transaction?   inspect   literal   literal_symbol   literal_symbol_set   load_adapter   log_connection_yield   log_exception   log_info   logger=   new   prepared_statement   quote_identifier   register_extension   remove_servers   rename_column   rename_table   rollback_checker   run   run_after_initialize   schema   schema_type_class   select   serial_primary_key_options   server_version   server_version   servers   set_column_default   set_column_type   set_prepared_statement   set_shared_adapter_scheme   sharded?   single_threaded?   supports_create_table_if_not_exists?   supports_deferrable_constraints?   supports_deferrable_foreign_key_constraints?   supports_drop_table_if_exists?   supports_foreign_key_parsing?   supports_index_parsing?   supports_partial_indexes?   supports_prepared_transactions?   supports_savepoints?   supports_savepoints_in_prepared_transactions?   supports_schema_parsing?   supports_table_listing?   supports_transaction_isolation_levels?   supports_transactional_ddl?   supports_view_listing?   supports_views_with_check_option?   supports_views_with_local_check_option?   synchronize   synchronize   table_exists?   test_connection   timezone   to_application_timestamp   transaction   typecast_value   uri   url   valid_connection?  

Included Modules

1 - Methods that execute queries and/or return results

This methods generally execute SQL code on the database server.

Constants

COLUMN_SCHEMA_DATETIME_TYPES = [:date, :datetime].freeze
COLUMN_SCHEMA_STRING_TYPES = [:string, :blob, :date, :datetime, :time, :enum, :set, :interval].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

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"

[Source]

    # File lib/sequel/database/query.rb, line 25
25:     def <<(sql)
26:       run(sql)
27:       self
28:     end

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

[Source]

    # File lib/sequel/database/query.rb, line 35
35:     def call(ps_name, hash={}, &block)
36:       prepared_statement(ps_name).call(hash, &block)
37:     end

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.

[Source]

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

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.

[Source]

    # File lib/sequel/database/query.rb, line 49
49:     def execute_dui(sql, opts=OPTS, &block)
50:       execute(sql, opts, &block)
51:     end

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.

[Source]

    # File lib/sequel/database/query.rb, line 56
56:     def execute_insert(sql, opts=OPTS, &block)
57:       execute_dui(sql, opts, &block)
58:     end

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

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

[Source]

    # File lib/sequel/database/query.rb, line 65
65:     def get(*args, &block)
66:       @default_dataset.get(*args, &block)
67:     end

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")

[Source]

    # File lib/sequel/database/query.rb, line 74
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

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}]]

[Source]

     # File lib/sequel/database/query.rb, line 121
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:       end
179:       Sequel.synchronize{@schemas[quoted_name] = cols} if cache_schema
180:       cols
181:     end

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.

[Source]

     # File lib/sequel/database/query.rb, line 191
191:     def table_exists?(name)
192:       sch, table_name = schema_and_table(name)
193:       name = SQL::QualifiedIdentifier.new(sch, table_name) if sch
194:       ds = from(name)
195:       transaction(:savepoint=>:only){_table_exists?(ds)}
196:       true
197:     rescue DatabaseError
198:       false
199:     end

8 - Methods related to database transactions

Database transactions make multiple queries atomic, so that either all of the queries take effect or none of them do.

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

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.

[Source]

    # File lib/sequel/database/transactions.rb, line 29
29:     def after_commit(opts=OPTS, &block)
30:       raise Error, "must provide block to after_commit" unless block
31:       synchronize(opts[:server]) do |conn|
32:         if h = _trans(conn)
33:           raise Error, "cannot call after_commit in a prepared transaction" if h[:prepare]
34:           add_transaction_hook(conn, :after_commit, block)
35:         else
36:           yield
37:         end
38:       end
39:     end

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.

[Source]

    # File lib/sequel/database/transactions.rb, line 46
46:     def after_rollback(opts=OPTS, &block)
47:       raise Error, "must provide block to after_rollback" unless block
48:       synchronize(opts[:server]) do |conn|
49:         if h = _trans(conn)
50:           raise Error, "cannot call after_rollback in a prepared transaction" if h[:prepare]
51:           add_transaction_hook(conn, :after_rollback, block)
52:         end
53:       end
54:     end

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

[Source]

    # File lib/sequel/database/transactions.rb, line 59
59:     def in_transaction?(opts=OPTS)
60:       synchronize(opts[:server]){|conn| !!_trans(conn)}
61:     end

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.

[Source]

    # File lib/sequel/database/transactions.rb, line 69
69:     def rollback_checker(opts=OPTS)
70:       synchronize(opts[:server]) do |conn|
71:         raise Error, "not in a transaction" unless t = _trans(conn)
72:         t[:rollback_checker] ||= proc{Sequel.synchronize{t[:rolled_back]}}
73:       end
74:     end

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 rertrying 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 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. 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.

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+).

[Source]

     # File lib/sequel/database/transactions.rb, line 123
123:     def transaction(opts=OPTS, &block)
124:       opts = Hash[opts]
125:       if retry_on = opts[:retry_on]
126:         tot_retries = opts.fetch(:num_retries, 5)
127:         num_retries = 0 unless tot_retries.nil?
128:         begin
129:           opts[:retry_on] = nil
130:           opts[:retrying] = true
131:           transaction(opts, &block)
132:         rescue *retry_on => e
133:           if num_retries
134:             num_retries += 1
135:             if num_retries <= tot_retries
136:               opts[:before_retry].call(num_retries, e) if opts[:before_retry]
137:               retry
138:             end
139:           else
140:             retry
141:           end
142:           raise
143:         end
144:       else
145:         synchronize(opts[:server]) do |conn|
146:           if opts[:savepoint] == :only
147:             if supports_savepoints?
148:               if _trans(conn)
149:                 opts[:savepoint] = true
150:               else
151:                 return yield(conn)
152:               end
153:             else
154:               opts[:savepoint] = false
155:             end
156:           end
157: 
158:           if already_in_transaction?(conn, opts)
159:             if opts[:rollback] == :always && !opts.has_key?(:savepoint)
160:               if supports_savepoints? 
161:                 opts[:savepoint] = true
162:               else
163:                 raise Sequel::Error, "cannot set :rollback=>:always transaction option if already inside a transaction"
164:               end
165:             end
166: 
167:             if opts[:savepoint] != false && (stack = _trans(conn)[:savepoints]) && stack.last
168:               opts[:savepoint] = true
169:             end
170: 
171:             unless opts[:savepoint]
172:               if opts[:retrying]
173:                 raise Sequel::Error, "cannot set :retry_on options if you are already inside a transaction"
174:               end
175:               return yield(conn)
176:             end
177:           end
178: 
179:           _transaction(conn, opts, &block)
180:         end
181:       end
182:     end

2 - Methods that modify the database schema

These methods execute code on the database that modifies the database‘s 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

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.

[Source]

    # File lib/sequel/database/schema_methods.rb, line 25
25:     def add_column(table, *args)
26:       alter_table(table) {add_column(*args)}
27:     end

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.

[Source]

    # File lib/sequel/database/schema_methods.rb, line 40
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

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 and Schema Modification" guide.

[Source]

    # File lib/sequel/database/schema_methods.rb, line 67
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

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

[Source]

    # File lib/sequel/database/schema_methods.rb, line 76
76:     def alter_table_generator(&block)
77:       alter_table_generator_class.new(self, &block)
78:     end

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.

[Source]

     # File lib/sequel/database/schema_methods.rb, line 112
112:     def create_join_table(hash, options=OPTS)
113:       keys = hash.keys.sort
114:       create_table(join_table_name(hash, options), options) do
115:         keys.each do |key|
116:           v = hash[key]
117:           unless v.is_a?(Hash)
118:             v = {:table=>v}
119:           end
120:           v[:null] = false unless v.has_key?(:null)
121:           foreign_key(key, v)
122:         end
123:         primary_key(keys) unless options[:no_primary_key]
124:         index(keys.reverse, options[:index_options] || {}) unless options[:no_index]
125:       end
126:       nil
127:     end

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

[Source]

     # File lib/sequel/database/schema_methods.rb, line 130
130:     def create_join_table!(hash, options=OPTS)
131:       drop_table?(join_table_name(hash, options))
132:       create_join_table(hash, options)
133:     end

Creates the join table unless it already exists.

[Source]

     # File lib/sequel/database/schema_methods.rb, line 136
136:     def create_join_table?(hash, options=OPTS)
137:       if supports_create_table_if_not_exists? && options[:no_index]
138:         create_join_table(hash, options.merge(:if_not_exists=>true))
139:       elsif !table_exists?(join_table_name(hash, options))
140:         create_join_table(hash, options)
141:       end
142:     end

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.

[Source]

     # File lib/sequel/database/schema_methods.rb, line 231
231:     def create_or_replace_view(name, source, options = OPTS)
232:       if supports_create_or_replace_view?
233:         options = options.merge(:replace=>true)
234:       else
235:         drop_view(name) rescue nil
236:       end
237: 
238:       create_view(name, source, options)
239:       nil
240:     end

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.

See Schema::CreateTableGenerator and the "Schema Modification" guide.

[Source]

     # File lib/sequel/database/schema_methods.rb, line 179
179:     def create_table(name, options=OPTS, &block)
180:       remove_cached_schema(name)
181:       if sql = options[:as]
182:         raise(Error, "can't provide both :as option and block to create_table") if block
183:         create_table_as(name, sql, options)
184:       else
185:         generator = options[:generator] || create_table_generator(&block)
186:         create_table_from_generator(name, generator, options)
187:         create_table_indexes_from_generator(name, generator, options)
188:       end
189:       nil
190:     end

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)

[Source]

     # File lib/sequel/database/schema_methods.rb, line 198
198:     def create_table!(name, options=OPTS, &block)
199:       drop_table?(name)
200:       create_table(name, options, &block)
201:     end

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

[Source]

     # File lib/sequel/database/schema_methods.rb, line 208
208:     def create_table?(name, options=OPTS, &block)
209:       options = options.dup
210:       generator = options[:generator] ||= create_table_generator(&block)
211:       if generator.indexes.empty? && supports_create_table_if_not_exists?
212:         create_table(name, options.merge!(:if_not_exists=>true))
213:       elsif !table_exists?(name)
214:         create_table(name, options)
215:       end
216:     end

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

[Source]

     # File lib/sequel/database/schema_methods.rb, line 220
220:     def create_table_generator(&block)
221:       create_table_generator_class.new(self, &block)
222:     end

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

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.

[Source]

     # File lib/sequel/database/schema_methods.rb, line 277
277:     def create_view(name, source, options = OPTS)
278:       execute_ddl(create_view_sql(name, source, options))
279:       remove_cached_schema(name)
280:       nil
281:     end

Removes a column from the specified table:

  DB.drop_column :items, :category

See alter_table.

[Source]

     # File lib/sequel/database/schema_methods.rb, line 288
288:     def drop_column(table, *args)
289:       alter_table(table) {drop_column(*args)}
290:     end

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

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

See alter_table.

[Source]

     # File lib/sequel/database/schema_methods.rb, line 298
298:     def drop_index(table, columns, options=OPTS)
299:       alter_table(table){drop_index(columns, options)}
300:     end

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

[Source]

     # File lib/sequel/database/schema_methods.rb, line 307
307:     def drop_join_table(hash, options=OPTS)
308:       drop_table(join_table_name(hash, options), options)
309:     end

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)

[Source]

     # File lib/sequel/database/schema_methods.rb, line 316
316:     def drop_table(*names)
317:       options = names.last.is_a?(Hash) ? names.pop : {}
318:       names.each do |n|
319:         execute_ddl(drop_table_sql(n, options))
320:         remove_cached_schema(n)
321:       end
322:       nil
323:     end

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

[Source]

     # File lib/sequel/database/schema_methods.rb, line 331
331:     def drop_table?(*names)
332:       options = names.last.is_a?(Hash) ? names.pop : {}
333:       if supports_drop_table_if_exists?
334:         options = options.merge(:if_exists=>true)
335:         names.each do |name|
336:           drop_table(name, options)
337:         end
338:       else
339:         names.each do |name|
340:           drop_table(name, options) if table_exists?(name)
341:         end
342:       end
343:       nil
344:     end

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.

[Source]

     # File lib/sequel/database/schema_methods.rb, line 359
359:     def drop_view(*names)
360:       options = names.last.is_a?(Hash) ? names.pop : {}
361:       names.each do |n|
362:         execute_ddl(drop_view_sql(n, options))
363:         remove_cached_schema(n)
364:       end
365:       nil
366:     end

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.

[Source]

     # File lib/sequel/database/schema_methods.rb, line 385
385:     def rename_column(table, *args)
386:       alter_table(table) {rename_column(*args)}
387:     end

Renames a table:

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

[Source]

     # File lib/sequel/database/schema_methods.rb, line 373
373:     def rename_table(name, new_name)
374:       execute_ddl(rename_table_sql(name, new_name))
375:       remove_cached_schema(name)
376:       nil
377:     end

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

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

See alter_table.

[Source]

     # File lib/sequel/database/schema_methods.rb, line 394
394:     def set_column_default(table, *args)
395:       alter_table(table) {set_column_default(*args)}
396:     end

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

  DB.set_column_type :items, :price, :float

See alter_table.

[Source]

     # File lib/sequel/database/schema_methods.rb, line 403
403:     def set_column_type(table, *args)
404:       alter_table(table) {set_column_type(*args)}
405:     end

6 - Methods relating to logging

This methods affect relating to the logging of executed SQL.

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

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.

[Source]

    # File lib/sequel/database/logging.rb, line 37
37:     def log_connection_yield(sql, conn, args=nil)
38:       return yield if @loggers.empty?
39:       sql = "#{connection_info(conn) if conn && log_connection_info}#{sql}#{"; #{args.inspect}" if args}"
40:       start = Time.now
41:       begin
42:         yield
43:       rescue => e
44:         log_exception(e, sql)
45:         raise
46:       ensure
47:         log_duration(Time.now - start, sql) unless e
48:       end
49:     end

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

[Source]

    # File lib/sequel/database/logging.rb, line 26
26:     def log_exception(exception, message)
27:       log_each(:error, "#{exception.class}: #{exception.message.strip if exception.message}: #{message}")
28:     end

Log a message at level info to all loggers.

[Source]

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

Remove any existing loggers and just use the given logger:

  DB.logger = Logger.new($stdout)

[Source]

    # File lib/sequel/database/logging.rb, line 54
54:     def logger=(logger)
55:       @loggers = Array(logger)
56:     end

7 - Miscellaneous methods

These methods don‘t fit neatly into another category.

Constants

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).
DEFAULT_STRING_COLUMN_SIZE = 255   The general default size for string columns for all Sequel::Database instances.
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.
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.
NOT_NULL_CONSTRAINT_SQLSTATES = %w'23502'.freeze.each(&:freeze)
FOREIGN_KEY_CONSTRAINT_SQLSTATES = %w'23503 23506 23504'.freeze.each(&:freeze)
UNIQUE_CONSTRAINT_SQLSTATES = %w'23505'.freeze.each(&:freeze)
CHECK_CONSTRAINT_SQLSTATES = %w'23513 23514'.freeze.each(&:freeze)
SERIALIZATION_CONSTRAINT_SQLSTATES = %w'40001'.freeze.each(&:freeze)

Attributes

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

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

[Source]

    # File lib/sequel/database/misc.rb, line 34
34:     def self.after_initialize(&block)
35:       raise Error, "must provide block to after_initialize" unless block
36:       Sequel.synchronize do
37:         previous = @initialize_hook
38:         @initialize_hook = Proc.new do |db|
39:           previous.call(db)
40:           block.call(db)
41:         end
42:       end
43:     end

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

[Source]

    # File lib/sequel/database/misc.rb, line 46
46:     def self.extension(*extensions)
47:       after_initialize{|db| db.extension(*extensions)}
48:     end

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

Accepts the following options:

:cache_schema :Whether schema should be cached for this Database instance
:default_string_column_size :The default size of string columns, 255 by default.
: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.
:preconnect :Whether to automatically connect to the maximum number of servers. Can use a valid of ‘concurrently’ to preconnect in separate threads.
: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.

[Source]

     # File lib/sequel/database/misc.rb, line 114
114:     def initialize(opts = OPTS)
115:       @opts ||= opts
116:       @opts = connection_pool_default_options.merge(@opts)
117:       @loggers = Array(@opts[:logger]) + Array(@opts[:loggers])
118:       @opts[:servers] = {} if @opts[:servers].is_a?(String)
119:       @sharded = !!@opts[:servers]
120:       @opts[:adapter_class] = self.class
121:       @opts[:single_threaded] = @single_threaded = typecast_value_boolean(@opts.fetch(:single_threaded, Sequel.single_threaded))
122:       @default_string_column_size = @opts[:default_string_column_size] || DEFAULT_STRING_COLUMN_SIZE
123: 
124:       @schemas = {}
125:       @prepared_statements = {}
126:       @transactions = {}
127:       @symbol_literal_cache = {}
128: 
129:       @timezone = nil
130: 
131:       @dataset_class = dataset_class_default
132:       @cache_schema = typecast_value_boolean(@opts.fetch(:cache_schema, true))
133:       @dataset_modules = []
134:       @loaded_extensions = []
135:       @schema_type_classes = SCHEMA_TYPE_CLASSES.dup
136: 
137:       self.sql_log_level = @opts[:sql_log_level] ? @opts[:sql_log_level].to_sym : :info
138:       self.log_warn_duration = @opts[:log_warn_duration]
139:       self.log_connection_info = typecast_value_boolean(@opts[:log_connection_info])
140: 
141:       @pool = ConnectionPool.get_pool(self, @opts)
142: 
143:       reset_default_dataset
144:       adapter_initialize
145: 
146:       unless typecast_value_boolean(@opts[:keep_reference]) == false
147:         Sequel.synchronize{::Sequel::DATABASES.push(self)}
148:       end
149:       Sequel::Database.run_after_initialize(self)
150:       if typecast_value_boolean(@opts[:preconnect]) && @pool.respond_to?(:preconnect, true)
151:         concurrent = typecast_value_string(@opts[:preconnect]) == "concurrently"
152:         @pool.send(:preconnect, concurrent)
153:       end
154:     end

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.

[Source]

    # File lib/sequel/database/misc.rb, line 55
55:     def self.register_extension(ext, mod=nil, &block)
56:       if mod
57:         raise(Error, "cannot provide both mod and block to Database.register_extension") if block
58:         if mod.is_a?(Module)
59:           block = proc{|db| db.extend(mod)}
60:         else
61:           block = mod
62:         end
63:       end
64:       Sequel.synchronize{EXTENSIONS[ext] = block}
65:     end

Run the after_initialize hook for the given instance.

[Source]

    # File lib/sequel/database/misc.rb, line 68
68:     def self.run_after_initialize(instance)
69:       @initialize_hook.call(instance)
70:     end

Public Instance methods

Cast the given type to a literal type

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

[Source]

     # File lib/sequel/database/misc.rb, line 181
181:     def cast_type_literal(type)
182:       type_literal(:type=>type)
183:     end

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.

[Source]

     # File lib/sequel/database/misc.rb, line 190
190:     def extension(*exts)
191:       Sequel.extension(*exts)
192:       exts.each do |ext|
193:         if pr = Sequel.synchronize{EXTENSIONS[ext]}
194:           unless Sequel.synchronize{@loaded_extensions.include?(ext)}
195:             Sequel.synchronize{@loaded_extensions << ext}
196:             pr.call(self)
197:           end
198:         else
199:           raise(Error, "Extension #{ext} does not have specific support handling individual databases (try: Sequel.extension #{ext.inspect})")
200:         end
201:       end
202:       self
203:     end

Freeze internal data structures for the Database instance.

[Source]

     # File lib/sequel/database/misc.rb, line 157
157:     def freeze
158:       valid_connection_sql
159:       metadata_dataset
160:       @opts.freeze
161:       @loggers.freeze
162:       @pool.freeze
163:       @dataset_class.freeze
164:       @dataset_modules.freeze
165:       @schema_type_classes.freeze
166:       @loaded_extensions.freeze
167:       metadata_dataset
168:       super
169:     end

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.

[Source]

     # File lib/sequel/database/misc.rb, line 208
208:     def from_application_timestamp(v)
209:       Sequel.convert_output_timestamp(v, timezone)
210:     end

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

[Source]

     # File lib/sequel/database/misc.rb, line 214
214:     def inspect
215:       a = []
216:       a << uri.inspect if uri
217:       if (oo = opts[:orig_opts]) && !oo.empty?
218:         a << oo.inspect
219:       end
220:       "#<#{self.class}: #{a.join(' ')}>"
221:     end

Proxy the literal call to the dataset.

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

[Source]

     # File lib/sequel/database/misc.rb, line 228
228:     def literal(v)
229:       schema_utility_dataset.literal(v)
230:     end

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

[Source]

     # File lib/sequel/database/misc.rb, line 234
234:     def literal_symbol(sym)
235:       Sequel.synchronize{@symbol_literal_cache[sym]}
236:     end

Set the cached value of the literal symbol.

[Source]

     # File lib/sequel/database/misc.rb, line 239
239:     def literal_symbol_set(sym, lit)
240:       Sequel.synchronize{@symbol_literal_cache[sym] = lit}
241:     end

Synchronize access to the prepared statements cache.

[Source]

     # File lib/sequel/database/misc.rb, line 244
244:     def prepared_statement(name)
245:       Sequel.synchronize{prepared_statements[name]}
246:     end

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

[Source]

     # File lib/sequel/database/misc.rb, line 251
251:     def quote_identifier(v)
252:       schema_utility_dataset.quote_identifier(v)
253:     end

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

[Source]

     # File lib/sequel/database/misc.rb, line 256
256:     def schema_type_class(type)
257:       @schema_type_classes[type]
258:     end

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

[Source]

     # File lib/sequel/database/misc.rb, line 261
261:     def serial_primary_key_options
262:       {:primary_key => true, :type => Integer, :auto_increment => true}
263:     end

Cache the prepared statement object at the given name.

[Source]

     # File lib/sequel/database/misc.rb, line 266
266:     def set_prepared_statement(name, ps)
267:       Sequel.synchronize{prepared_statements[name] = ps}
268:     end

Whether this database instance uses multiple servers, either for sharding or for master/slave.

[Source]

     # File lib/sequel/database/misc.rb, line 272
272:     def sharded?
273:       @sharded
274:     end

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

[Source]

     # File lib/sequel/database/misc.rb, line 277
277:     def timezone
278:       @timezone || Sequel.database_timezone
279:     end

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.

[Source]

     # File lib/sequel/database/misc.rb, line 284
284:     def to_application_timestamp(v)
285:       Sequel.convert_timestamp(v, timezone)
286:     end

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.

[Source]

     # File lib/sequel/database/misc.rb, line 293
293:     def typecast_value(column_type, value)
294:       return nil if value.nil?
295:       meth = "typecast_value_#{column_type}"
296:       begin
297:         # Allow calling private methods as per-type typecasting methods are private
298:         respond_to?(meth, true) ? send(meth, value) : value
299:       rescue ArgumentError, TypeError => e
300:         raise Sequel.convert_exception_class(e, InvalidValue)
301:       end
302:     end

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

[Source]

     # File lib/sequel/database/misc.rb, line 306
306:     def uri
307:       opts[:uri]
308:     end

Explicit alias of uri for easier subclassing.

[Source]

     # File lib/sequel/database/misc.rb, line 311
311:     def url
312:       uri
313:     end

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

This methods involve the Database‘s connection pool.

Constants

ADAPTERS = %w'ado amalgalite ibmdb jdbc mock mysql mysql2 odbc oracle postgres sqlanywhere sqlite tinytds'.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

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

[Source]

    # File lib/sequel/database/connecting.rb, line 16
16:     def self.adapter_class(scheme)
17:       scheme.is_a?(Class) ? scheme : load_adapter(scheme.to_sym)
18:     end

Returns the scheme symbol for the Database class.

[Source]

    # File lib/sequel/database/connecting.rb, line 21
21:     def self.adapter_scheme
22:       @scheme
23:     end

Connects to a database. See Sequel.connect.

[Source]

    # File lib/sequel/database/connecting.rb, line 26
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:           uri_options = c.send(:uri_to_options, uri)
38:           uri.query.split('&').map{|s| s.split('=')}.each{|k,v| uri_options[k.to_sym] = v if k && !k.empty?} unless uri.query.to_s.strip.empty?
39:           uri_options.to_a.each{|k,v| uri_options[k] = (defined?(URI::DEFAULT_PARSER) ? URI::DEFAULT_PARSER : URI).unescape(v) if v.is_a?(String)}
40:           opts = uri_options.merge(opts).merge!(:orig_opts=>opts.dup, :uri=>conn_string, :adapter=>scheme)
41:         end
42:       when Hash
43:         opts = conn_string.merge(opts)
44:         opts = opts.merge(:orig_opts=>opts.dup)
45:         c = adapter_class(opts[:adapter_class] || opts[:adapter] || opts['adapter'])
46:       else
47:         raise Error, "Sequel::Database.connect takes either a Hash or a String, given: #{conn_string.inspect}"
48:       end
49: 
50:       opts = opts.inject({}) do |m, (k,v)|
51:         k = :user if k.to_s == 'username'
52:         m[k.to_sym] = v
53:         m
54:       end
55: 
56:       begin
57:         db = c.new(opts)
58:         db.test_connection if db.send(:typecast_value_boolean, opts.fetch(:test, true))
59:         if block_given?
60:           return yield(db)
61:         end
62:       ensure
63:         if block_given?
64:           db.disconnect if db
65:           Sequel.synchronize{::Sequel::DATABASES.delete(db)}
66:         end
67:       end
68:       db
69:     end

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.

[Source]

     # File lib/sequel/database/connecting.rb, line 77
 77:     def self.load_adapter(scheme, opts=OPTS)
 78:       map = opts[:map] || ADAPTER_MAP
 79:       if subdir = opts[:subdir]
 80:         file = "#{subdir}/#{scheme}"
 81:       else
 82:         file = scheme
 83:       end
 84:       
 85:       unless obj = Sequel.synchronize{map[scheme]}
 86:         # attempt to load the adapter file
 87:         begin
 88:           require "sequel/adapters/#{file}"
 89:         rescue LoadError => e
 90:           # If subadapter file doesn't exist, just return, 
 91:           # using the main adapter class without database customizations.
 92:           return if subdir
 93:           raise Sequel.convert_exception_class(e, AdapterNotFound)
 94:         end
 95:         
 96:         # make sure we actually loaded the adapter
 97:         unless obj = Sequel.synchronize{map[scheme]}
 98:           raise AdapterNotFound, "Could not load #{file} adapter: adapter class not registered in ADAPTER_MAP"
 99:         end
100:       end
101: 
102:       obj
103:     end

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')

[Source]

     # File lib/sequel/database/connecting.rb, line 147
147:     def self.set_shared_adapter_scheme(scheme, mod)
148:       Sequel.synchronize{SHARED_ADAPTER_MAP[scheme] = mod}
149:     end

Public Instance methods

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

[Source]

     # File lib/sequel/database/connecting.rb, line 162
162:     def adapter_scheme
163:       self.class.adapter_scheme
164:     end

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"})

[Source]

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

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

[Source]

     # File lib/sequel/database/connecting.rb, line 193
193:     def database_type
194:       adapter_scheme
195:     end

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

[Source]

     # File lib/sequel/database/connecting.rb, line 207
207:     def disconnect(opts = OPTS)
208:       pool.disconnect(opts)
209:     end

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.

[Source]

     # File lib/sequel/database/connecting.rb, line 214
214:     def disconnect_connection(conn)
215:       conn.close
216:     end

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)

[Source]

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

An array of servers/shards for this Database object.

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

[Source]

     # File lib/sequel/database/connecting.rb, line 241
241:     def servers
242:       pool.servers
243:     end

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

[Source]

     # File lib/sequel/database/connecting.rb, line 246
246:     def single_threaded?
247:       @single_threaded
248:     end

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

[Source]

     # File lib/sequel/database/connecting.rb, line 263
263:       def synchronize(server=nil)
264:         @pool.hold(server || :default){|conn| yield conn}
265:       end

:nocov:

[Source]

     # File lib/sequel/database/connecting.rb, line 268
268:       def synchronize(server=nil, &block)
269:         @pool.hold(server || :default, &block)
270:       end

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.

[Source]

     # File lib/sequel/database/connecting.rb, line 278
278:     def test_connection(server=nil)
279:       synchronize(server){|conn|}
280:       true
281:     end

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.

[Source]

     # File lib/sequel/database/connecting.rb, line 287
287:     def valid_connection?(conn)
288:       sql = valid_connection_sql
289:       begin
290:         log_connection_execute(conn, sql)
291:       rescue Sequel::DatabaseError, *database_error_classes
292:         false
293:       else
294:         true
295:       end
296:     end

3 - Methods that create datasets

These methods all return instances of this database‘s dataset class.

Public Instance methods

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"

[Source]

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

Returns a blank dataset for this database.

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

[Source]

    # File lib/sequel/database/dataset.rb, line 29
29:     def dataset
30:       @dataset_class.new(self)
31:     end

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

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

[Source]

    # File lib/sequel/database/dataset.rb, line 49
49:     def fetch(sql, *args, &block)
50:       ds = @default_dataset.with_sql(sql, *args)
51:       ds.each(&block) if block
52:       ds
53:     end

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

[Source]

    # File lib/sequel/database/dataset.rb, line 60
60:     def from(*args, &block)
61:       if block
62:         @default_dataset.from(*args, &block)
63:       elsif args.length == 1 && (table = args[0]).is_a?(Symbol)
64:         @default_dataset.send(:cached_dataset, "_from_#{table}_ds""_from_#{table}_ds"){@default_dataset.from(table)}
65:       else
66:         @default_dataset.from(*args)
67:       end
68:     end

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

[Source]

    # File lib/sequel/database/dataset.rb, line 75
75:     def select(*args, &block)
76:       @default_dataset.select(*args, &block)
77:     end

9 - Methods that describe what the database supports

These methods all return booleans, with most describing whether or not the database supprots a given feature.

Public Instance methods

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

[Source]

    # File lib/sequel/database/features.rb, line 13
13:     def global_index_namespace?
14:       true
15:     end

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

[Source]

    # File lib/sequel/database/features.rb, line 19
19:     def supports_create_table_if_not_exists?
20:       false
21:     end

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

[Source]

    # File lib/sequel/database/features.rb, line 25
25:     def supports_deferrable_constraints?
26:       false
27:     end

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

[Source]

    # File lib/sequel/database/features.rb, line 31
31:     def supports_deferrable_foreign_key_constraints?
32:       supports_deferrable_constraints?
33:     end

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

[Source]

    # File lib/sequel/database/features.rb, line 37
37:     def supports_drop_table_if_exists?
38:       supports_create_table_if_not_exists?
39:     end

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

[Source]

    # File lib/sequel/database/features.rb, line 43
43:     def supports_foreign_key_parsing?
44:       respond_to?(:foreign_key_list)
45:     end

Whether the database supports Database#indexes for parsing indexes.

[Source]

    # File lib/sequel/database/features.rb, line 48
48:     def supports_index_parsing?
49:       respond_to?(:indexes)
50:     end

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

[Source]

    # File lib/sequel/database/features.rb, line 54
54:     def supports_partial_indexes?
55:       false
56:     end

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

[Source]

    # File lib/sequel/database/features.rb, line 60
60:     def supports_prepared_transactions?
61:       false
62:     end

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

[Source]

    # File lib/sequel/database/features.rb, line 65
65:     def supports_savepoints?
66:       false
67:     end

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

[Source]

    # File lib/sequel/database/features.rb, line 71
71:     def supports_savepoints_in_prepared_transactions?
72:       supports_prepared_transactions? && supports_savepoints?
73:     end

Whether the database supports schema parsing via Database#schema.

[Source]

    # File lib/sequel/database/features.rb, line 76
76:     def supports_schema_parsing?
77:       respond_to?(:schema_parse_table, true)
78:     end

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

[Source]

    # File lib/sequel/database/features.rb, line 81
81:     def supports_table_listing?
82:       respond_to?(:tables)
83:     end

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

[Source]

    # File lib/sequel/database/features.rb, line 91
91:     def supports_transaction_isolation_levels?
92:       false
93:     end

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

[Source]

    # File lib/sequel/database/features.rb, line 96
96:     def supports_transactional_ddl?
97:       false
98:     end

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

[Source]

    # File lib/sequel/database/features.rb, line 86
86:     def supports_view_listing?
87:       respond_to?(:views)
88:     end

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

[Source]

     # File lib/sequel/database/features.rb, line 101
101:     def supports_views_with_check_option?
102:       !!view_with_check_option_support
103:     end

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

[Source]

     # File lib/sequel/database/features.rb, line 106
106:     def supports_views_with_local_check_option?
107:       view_with_check_option_support == :local
108:     end

5 - Methods that set defaults for created datasets

This methods change the default behavior of this database‘s datasets.

Classes and Modules

Module Sequel::Database::SplitAlterTable

Constants

OPTS = Sequel::OPTS

Attributes

conversion_procs  [R]  Hash of conversion procs for the current database
convert_invalid_date_time  [R]  By default, Sequel raises an exception if in invalid date or time is used. However, if this is set to nil or :nil, the adapter treats dates like 0000-00-00 and times like 838:00:00 as nil values. If set to :string, it returns the strings as is.
convert_tinyint_to_bool  [RW]  Whether to convert tinyint columns to bool for this database
convert_tinyint_to_bool  [R]  Whether to convert tinyint columns to bool for the current database
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

Connect to the database. In addition to the usual database options, the following options have effect:

:auto_is_null :Set to true to use MySQL default behavior of having a filter for an autoincrement column equals NULL to return the last inserted row.
:charset :Same as :encoding (:encoding takes precendence)
:compress :Set to false to not compress results from the server
:config_default_group :The default group to read from the in the MySQL config file.
:config_local_infile :If provided, sets the Mysql::OPT_LOCAL_INFILE option on the connection with the given value.
:connect_timeout :Set the timeout in seconds before a connection attempt is abandoned.
:encoding :Set all the related character sets for this connection (connection, client, database, server, and results).
:read_timeout :Set the timeout in seconds for reading back results to a query.
:socket :Use a unix socket file instead of connecting via TCP/IP.
:timeout :Set the timeout in seconds before the server will disconnect this connection (a.k.a @@wait_timeout).

[Source]

     # File lib/sequel/adapters/mysql.rb, line 73
 73:       def connect(server)
 74:         opts = server_opts(server)
 75:         conn = Mysql.init
 76:         conn.options(Mysql::READ_DEFAULT_GROUP, opts[:config_default_group] || "client")
 77:         conn.options(Mysql::OPT_LOCAL_INFILE, opts[:config_local_infile]) if opts.has_key?(:config_local_infile)
 78:         conn.ssl_set(opts[:sslkey], opts[:sslcert], opts[:sslca], opts[:sslcapath], opts[:sslcipher]) if opts[:sslca] || opts[:sslkey]
 79:         if encoding = opts[:encoding] || opts[:charset]
 80:           # Set encoding before connecting so that the mysql driver knows what
 81:           # encoding we want to use, but this can be overridden by READ_DEFAULT_GROUP.
 82:           conn.options(Mysql::SET_CHARSET_NAME, encoding)
 83:         end
 84:         if read_timeout = opts[:read_timeout] and defined? Mysql::OPT_READ_TIMEOUT
 85:           conn.options(Mysql::OPT_READ_TIMEOUT, read_timeout)
 86:         end
 87:         if connect_timeout = opts[:connect_timeout] and defined? Mysql::OPT_CONNECT_TIMEOUT
 88:           conn.options(Mysql::OPT_CONNECT_TIMEOUT, connect_timeout)
 89:         end
 90:         conn.real_connect(
 91:           opts[:host] || 'localhost',
 92:           opts[:user],
 93:           opts[:password],
 94:           opts[:database],
 95:           (opts[:port].to_i if opts[:port]),
 96:           opts[:socket],
 97:           Mysql::CLIENT_MULTI_RESULTS +
 98:           Mysql::CLIENT_MULTI_STATEMENTS +
 99:           (opts[:compress] == false ? 0 : Mysql::CLIENT_COMPRESS)
100:         )
101:         sqls = mysql_connection_setting_sqls
102: 
103:         # Set encoding a slightly different way after connecting,
104:         # in case the READ_DEFAULT_GROUP overrode the provided encoding.
105:         # Doesn't work across implicit reconnects, but Sequel doesn't turn on
106:         # that feature.
107:         sqls.unshift("SET NAMES #{literal(encoding.to_s)}") if encoding
108: 
109:         sqls.each{|sql| log_connection_yield(sql, conn){conn.query(sql)}}
110: 
111:         add_prepared_statements_cache(conn)
112:         conn
113:       end

Connect to the database. In addition to the usual database options, the following options have effect:

:auto_is_null :Set to true to use MySQL default behavior of having a filter for an autoincrement column equals NULL to return the last inserted row.
:charset :Same as :encoding (:encoding takes precendence)
:encoding :Set all the related character sets for this connection (connection, client, database, server, and results).

The options hash is also passed to mysql2, and can include mysql2 options such as :local_infile.

[Source]

    # File lib/sequel/adapters/mysql2.rb, line 37
37:       def connect(server)
38:         opts = server_opts(server)
39:         opts[:host] ||= 'localhost'
40:         opts[:username] ||= opts.delete(:user)
41:         opts[:flags] ||= 0
42:         opts[:flags] |= ::Mysql2::Client::FOUND_ROWS if ::Mysql2::Client.const_defined?(:FOUND_ROWS)
43:         opts[:encoding] ||= opts[:charset]
44:         conn = ::Mysql2::Client.new(opts)
45:         conn.query_options.merge!(:symbolize_keys=>true, :cache_rows=>false)
46:           
47:         if NativePreparedStatements
48:           conn.instance_variable_set(:@sequel_default_query_options, conn.query_options.dup)
49:         end
50: 
51:         sqls = mysql_connection_setting_sqls
52: 
53:         # Set encoding a slightly different way after connecting,
54:         # in case the READ_DEFAULT_GROUP overrode the provided encoding.
55:         # Doesn't work across implicit reconnects, but Sequel doesn't turn on
56:         # that feature.
57:         if encoding = opts[:encoding]
58:           sqls.unshift("SET NAMES #{conn.escape(encoding.to_s)}")
59:         end
60: 
61:         sqls.each{|sql| log_connection_yield(sql, conn){conn.query(sql)}}
62: 
63:         add_prepared_statements_cache(conn)
64:         conn
65:       end

Modify the type translators for the date, time, and timestamp types depending on the value given.

[Source]

     # File lib/sequel/adapters/mysql.rb, line 123
123:       def convert_invalid_date_time=(v)
124:         m0 = ::Sequel.method(:string_to_time)
125:         @conversion_procs[11] = (v != false) ?  lambda{|val| convert_date_time(val, &m0)} : m0
126:         m1 = ::Sequel.method(:string_to_date) 
127:         m = (v != false) ? lambda{|val| convert_date_time(val, &m1)} : m1
128:         [10, 14].each{|i| @conversion_procs[i] = m}
129:         m2 = method(:to_application_timestamp)
130:         m = (v != false) ? lambda{|val| convert_date_time(val, &m2)} : m2
131:         [7, 12].each{|i| @conversion_procs[i] = m}
132:         @convert_invalid_date_time = v
133:       end

Modify the type translator used for the tinyint type based on the value given.

[Source]

     # File lib/sequel/adapters/mysql.rb, line 137
137:       def convert_tinyint_to_bool=(v)
138:         @conversion_procs[1] = TYPE_TRANSLATOR.method(v ? :boolean : :integer)
139:         @convert_tinyint_to_bool = v
140:       end

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.

[Source]

    # File lib/sequel/database/dataset_defaults.rb, line 18
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

[Source]

     # File lib/sequel/adapters/mysql.rb, line 115
115:       def disconnect_connection(c)
116:         c.close
117:       rescue Mysql::Error
118:         nil
119:       end

[Source]

    # File lib/sequel/adapters/mysql2.rb, line 67
67:       def execute_dui(sql, opts=OPTS)
68:         execute(sql, opts){|c| return c.affected_rows}
69:       end

[Source]

     # File lib/sequel/adapters/mysql.rb, line 142
142:       def execute_dui(sql, opts=OPTS)
143:         execute(sql, opts){|c| return affected_rows(c)}
144:       end

[Source]

     # File lib/sequel/adapters/mysql.rb, line 146
146:       def execute_insert(sql, opts=OPTS)
147:         execute(sql, opts){|c| return c.insert_id}
148:       end

[Source]

    # File lib/sequel/adapters/mysql2.rb, line 71
71:       def execute_insert(sql, opts=OPTS)
72:         execute(sql, opts){|c| return c.last_id}
73:       end

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

[Source]

    # File lib/sequel/database/dataset_defaults.rb, line 62
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

[Source]

    # File lib/sequel/adapters/mysql2.rb, line 75
75:       def freeze
76:         server_version
77:         super
78:       end

[Source]

     # File lib/sequel/adapters/mysql.rb, line 150
150:       def freeze
151:         server_version
152:         @conversion_procs.freeze
153:         super
154:       end

Return the version of the MySQL server to which we are connecting.

[Source]

    # File lib/sequel/adapters/mysql2.rb, line 81
81:       def server_version(server=nil)
82:         @server_version ||= (synchronize(server){|conn| conn.server_info[:id]} || super)
83:       end

Return the version of the MySQL server to which we are connecting.

[Source]

     # File lib/sequel/adapters/mysql.rb, line 157
157:       def server_version(server=nil)
158:         @server_version ||= (synchronize(server){|conn| conn.server_version if conn.respond_to?(:server_version)} || super)
159:       end