Class: Sequel::Database

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

Overview

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

Defined Under Namespace

Modules: FromBlock, ResetIdentifierMangling, SplitAlterTable

Constant Summary collapse

OPTS = 
Sequel::OPTS
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 =

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

255
DEFAULT_DATABASE_ERROR_REGEXPS =

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

{}.freeze
SCHEMA_TYPE_CLASSES =

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

{: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
STRING_DEFAULT_RE =

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

/\A'(.*)'\z/
CURRENT_TIMESTAMP_RE = 
/now|today|CURRENT|getdate|\ADate\(\)\z/io
COLUMN_SCHEMA_DATETIME_TYPES = 
[:date, :datetime]
COLUMN_SCHEMA_STRING_TYPES = 
[:string, :blob, :date, :datetime, :time, :enum, :set, :interval]
ADAPTERS =

Array of supported database adapters

%w'ado amalgalite cubrid do firebird ibmdb informix jdbc mock mysql mysql2 odbc oracle postgres sqlanywhere sqlite swift tinytds'.collect(&:to_sym)
SQL_BEGIN =

:section: 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.

'BEGIN'.freeze
SQL_COMMIT = 
'COMMIT'.freeze
SQL_RELEASE_SAVEPOINT = 
'RELEASE SAVEPOINT autopoint_%d'.freeze
SQL_ROLLBACK = 
'ROLLBACK'.freeze
SQL_ROLLBACK_TO_SAVEPOINT = 
'ROLLBACK TO SAVEPOINT autopoint_%d'.freeze
SQL_SAVEPOINT = 
'SAVEPOINT autopoint_%d'.freeze
TRANSACTION_BEGIN = 
'Transaction.begin'.freeze
TRANSACTION_COMMIT = 
'Transaction.commit'.freeze
TRANSACTION_ROLLBACK = 
'Transaction.rollback'.freeze
TRANSACTION_ISOLATION_LEVELS = 
{:uncommitted=>'READ UNCOMMITTED'.freeze,
:committed=>'READ COMMITTED'.freeze,
:repeatable=>'REPEATABLE READ'.freeze,
:serializable=>'SERIALIZABLE'.freeze}
AUTOINCREMENT =

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

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

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

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

The default options for join table columns.

{:null=>false}
COMBINABLE_ALTER_TABLE_OPS =

The alter table operations that are combinable.

[:add_column, :drop_column, :rename_column,
:set_column_type, :set_column_default, :set_column_null,
:add_constraint, :drop_constraint]
DatasetClass =

The default class to use for datasets

Sequel::Dataset

Class Attribute Summary collapse

Instance Attribute Summary collapse

Class Method Summary collapse

Instance Method Summary collapse

Methods included from Metaprogramming

meta_def

Constructor Details

#initialize(opts = OPTS, &block) ⇒ Database

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

Accepts the following options:

:default_string_column_size

The default size of string columns, 255 by default.

:identifier_input_method

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

:identifier_output_method

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

:logger

A specific logger to use.

:loggers

An array of loggers to use.

:preconnect

Whether to automatically connect to the maximum number of servers.

: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.



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

def initialize(opts = OPTS, &block)
  @opts ||= opts
  @opts = connection_pool_default_options.merge(@opts)
  @loggers = Array(@opts[:logger]) + Array(@opts[:loggers])
  self.log_warn_duration = @opts[:log_warn_duration]
  block ||= proc{|server| connect(server)}
  @opts[:servers] = {} if @opts[:servers].is_a?(String)
  @sharded = !!@opts[:servers]
  @opts[:adapter_class] = self.class
  
  @opts[:single_threaded] = @single_threaded = typecast_value_boolean(@opts.fetch(:single_threaded, Database.single_threaded))
  @schemas = {}
  @default_string_column_size = @opts[:default_string_column_size] || DEFAULT_STRING_COLUMN_SIZE
  @prepared_statements = {}
  @transactions = {}
  @identifier_input_method = nil
  @identifier_output_method = nil
  @quote_identifiers = nil
  @timezone = nil
  @dataset_class = dataset_class_default
  @cache_schema = typecast_value_boolean(@opts.fetch(:cache_schema, true))
  @dataset_modules = []
  @symbol_literal_cache = {}
  @schema_type_classes = SCHEMA_TYPE_CLASSES.dup
  self.sql_log_level = @opts[:sql_log_level] ? @opts[:sql_log_level].to_sym : :info
  @pool = ConnectionPool.get_pool(self, @opts)

  reset_identifier_mangling
  adapter_initialize

  unless typecast_value_boolean(@opts[:keep_reference]) == false
    Sequel.synchronize{::Sequel::DATABASES.push(self)}
  end
  Sequel::Database.run_after_initialize(self)
  @pool.send(:preconnect) if typecast_value_boolean(@opts[:preconnect]) && @pool.respond_to?(:preconnect, true)
end

Class Attribute Details

.identifier_input_method ⇒ Object

The identifier input method to use by default for all databases (default: adapter default)



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# File 'lib/sequel/database/dataset_defaults.rb', line 17

def identifier_input_method
  @identifier_input_method
end

.identifier_output_method ⇒ Object

The identifier output method to use by default for all databases (default: adapter default)



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# File 'lib/sequel/database/dataset_defaults.rb', line 20

def identifier_output_method
  @identifier_output_method
end

.quote_identifiers ⇒ Object

Whether to quote identifiers (columns and tables) by default for all databases (default: adapter default)



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

def quote_identifiers
  @quote_identifiers
end

.single_threaded ⇒ Object

Whether to use the single threaded connection pool by default



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# File 'lib/sequel/database/connecting.rb', line 15

def single_threaded
  @single_threaded
end

Instance Attribute Details

#cache_schema ⇒ Object

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



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# File 'lib/sequel/database/query.rb', line 19

def cache_schema
  @cache_schema
end

#dataset_class ⇒ Object

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



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

def dataset_class
  @dataset_class
end

#default_string_column_size ⇒ Object

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



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# File 'lib/sequel/database/misc.rb', line 96

def default_string_column_size
  @default_string_column_size
end

#identifier_input_method ⇒ Object

The identifier input method to use by default for this database (default: adapter default)



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# File 'lib/sequel/database/dataset_defaults.rb', line 42

def identifier_input_method
  @identifier_input_method
end

#identifier_output_method ⇒ Object

The identifier output method to use by default for this database (default: adapter default)



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

def identifier_output_method
  @identifier_output_method
end

#log_warn_duration ⇒ Object

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



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

def log_warn_duration
  @log_warn_duration
end

#loggers ⇒ Object

Array of SQL loggers to use for this database.



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

def loggers
  @loggers
end

#opts ⇒ Object (readonly)

The options hash for this database



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# File 'lib/sequel/database/misc.rb', line 90

def opts
  @opts
end

#pool ⇒ Object (readonly)

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



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# File 'lib/sequel/database/connecting.rb', line 133

def pool
  @pool
end

#prepared_statements ⇒ Object (readonly)

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



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# File 'lib/sequel/database/query.rb', line 14

def prepared_statements
  @prepared_statements
end

#sql_log_level ⇒ Object

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



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

def sql_log_level
  @sql_log_level
end

#timezone ⇒ Object

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



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# File 'lib/sequel/database/misc.rb', line 289

def timezone
  @timezone || Sequel.database_timezone
end

#transaction_isolation_level ⇒ Object

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



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# File 'lib/sequel/database/transactions.rb', line 31

def transaction_isolation_level
  @transaction_isolation_level
end

Class Method Details

.adapter_class(scheme) ⇒ Object

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



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# File 'lib/sequel/database/connecting.rb', line 21

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

  scheme = scheme.to_s.gsub('-', '_').to_sym

  load_adapter(scheme)
end

.adapter_scheme ⇒ Object

Returns the scheme symbol for the Database class.



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# File 'lib/sequel/database/connecting.rb', line 30

def self.adapter_scheme
  @scheme
end

.after_initialize(&block) ⇒ Object

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

Raises:



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# File 'lib/sequel/database/misc.rb', line 40

def self.after_initialize(&block)
  raise Error, "must provide block to after_initialize" unless block
  Sequel.synchronize do
    previous = @initialize_hook
    @initialize_hook = Proc.new do |db|
      previous.call(db)
      block.call(db)
    end
  end
end

.connect(conn_string, opts = OPTS) ⇒ Object

Connects to a database. See Sequel.connect.



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# File 'lib/sequel/database/connecting.rb', line 35

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

.extension(*extensions) ⇒ Object

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



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# File 'lib/sequel/database/misc.rb', line 52

def self.extension(*extensions)
  after_initialize{|db| db.extension(*extensions)}
end

.load_adapter(scheme, opts = OPTS) ⇒ Object

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.



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# File 'lib/sequel/database/connecting.rb', line 85

def self.load_adapter(scheme, opts=OPTS)
  map = opts[:map] || ADAPTER_MAP
  if subdir = opts[:subdir]
    file = "#{subdir}/#{scheme}"
  else
    file = scheme
  end
  
  unless obj = Sequel.synchronize{map[scheme]}
    # attempt to load the adapter file
    begin
      require "sequel/adapters/#{file}"
    rescue LoadError => e
      # If subadapter file doesn't exist, just return, 
      # using the main adapter class without database customizations.
      return if subdir
      raise Sequel.convert_exception_class(e, AdapterNotFound)
    end
    
    # make sure we actually loaded the adapter
    unless obj = Sequel.synchronize{map[scheme]}
      raise AdapterNotFound, "Could not load #{file} adapter: adapter class not registered in ADAPTER_MAP"
    end
  end

  obj
end

.register_extension(ext, mod = nil, &block) ⇒ Object

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.



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# File 'lib/sequel/database/misc.rb', line 61

def self.register_extension(ext, mod=nil, &block)
  if mod
    raise(Error, "cannot provide both mod and block to Database.register_extension") if block
    if mod.is_a?(Module)
      block = proc{|db| db.extend(mod)}
    else
      block = mod
    end
  end
  Sequel.synchronize{EXTENSIONS[ext] = block}
end

.run_after_initialize(instance) ⇒ Object

Run the after_initialize hook for the given instance.



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# File 'lib/sequel/database/misc.rb', line 74

def self.run_after_initialize(instance)
  @initialize_hook.call(instance)
end

Instance Method Details

#<<(sql) ⇒ Object

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

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



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# File 'lib/sequel/database/query.rb', line 25

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

#[](*args) ⇒ Object

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

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

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

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



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

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

#adapter_scheme ⇒ Object

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

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



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# File 'lib/sequel/database/connecting.rb', line 141

def adapter_scheme
  self.class.adapter_scheme
end

#add_column(table, *args) ⇒ Object

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

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

See alter_table.



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# File 'lib/sequel/database/schema_methods.rb', line 36

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

#add_index(table, columns, options = OPTS) ⇒ Object

Adds an index to a table for the given columns:

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

Options:

:ignore_errors

Ignore any DatabaseErrors that are raised

:name

Name to use for index instead of default

See alter_table.



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# File 'lib/sequel/database/schema_methods.rb', line 50

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

#add_servers(servers) ⇒ Object

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

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

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



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# File 'lib/sequel/database/connecting.rb', line 154

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

#after_commit(opts = OPTS, &block) ⇒ Object

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

:server

The server/shard to use.

Raises:



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# File 'lib/sequel/database/misc.rb', line 156

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

#after_rollback(opts = OPTS, &block) ⇒ Object

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

:server

The server/shard to use.

Raises:



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# File 'lib/sequel/database/misc.rb', line 173

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

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

Alters the given table with the specified block. Example:

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

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

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



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# File 'lib/sequel/database/schema_methods.rb', line 76

def alter_table(name, generator=nil, &block)
  generator ||= alter_table_generator(&block)
  remove_cached_schema(name)
  apply_alter_table_generator(name, generator)
  nil
end

#alter_table_generator(&block) ⇒ Object

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



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# File 'lib/sequel/database/schema_methods.rb', line 85

def alter_table_generator(&block)
  alter_table_generator_class.new(self, &block)
end

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

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

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



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# File 'lib/sequel/database/query.rb', line 35

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

#cast_type_literal(type) ⇒ Object

Cast the given type to a literal type

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



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

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

#create_join_table(hash, options = OPTS) ⇒ Object

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

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

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

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

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

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

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

Some table options are handled specially:

:index_options

The options to pass to the index

:name

The name of the table to create

:no_index

Set to true not to create the second index.

:no_primary_key

Set to true to not create the primary key.



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# File 'lib/sequel/database/schema_methods.rb', line 121

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

#create_join_table!(hash, options = OPTS) ⇒ Object

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



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# File 'lib/sequel/database/schema_methods.rb', line 138

def create_join_table!(hash, options=OPTS)
  drop_table?(join_table_name(hash, options))
  create_join_table(hash, options)
end

#create_join_table?(hash, options = OPTS) ⇒ Boolean

Creates the join table unless it already exists.

Returns:

  • (Boolean) 


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# File 'lib/sequel/database/schema_methods.rb', line 144

def create_join_table?(hash, options=OPTS)
  if supports_create_table_if_not_exists? && options[:no_index]
    create_join_table(hash, options.merge(:if_not_exists=>true))
  elsif !table_exists?(join_table_name(hash, options))
    create_join_table(hash, options)
  end
end

#create_or_replace_view(name, source, options = OPTS) ⇒ Object

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].filter(: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.



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# File 'lib/sequel/database/schema_methods.rb', line 240

def create_or_replace_view(name, source, options = OPTS)
  if supports_create_or_replace_view?
    options = options.merge(:replace=>true)
  else
    drop_view(name) rescue nil
  end

  create_view(name, source, options)
end

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

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

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

General options:

:as

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

:ignore_index_errors

Ignore any errors when creating indexes.

:temp

Create the table as a temporary table.

MySQL specific options:

:charset

The character set to use for the table.

:collate

The collation to use for the table.

:engine

The table engine to use for the table.

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::Generator and the “Schema Modification” guide.



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# File 'lib/sequel/database/schema_methods.rb', line 187

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

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

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

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



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# File 'lib/sequel/database/schema_methods.rb', line 207

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

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

Creates the table unless the table already exists.

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

Returns:

  • (Boolean) 


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# File 'lib/sequel/database/schema_methods.rb', line 217

def create_table?(name, options=OPTS, &block)
  options = options.dup
  generator = options[:generator] ||= create_table_generator(&block)
  if generator.indexes.empty? && supports_create_table_if_not_exists?
    create_table(name, options.merge!(:if_not_exists=>true))
  elsif !table_exists?(name)
    create_table(name, options)
  end
end

#create_table_generator(&block) ⇒ Object

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



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

def create_table_generator(&block)
  create_table_generator_class.new(self, &block)
end

#create_view(name, source, options = OPTS) ⇒ Object

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.



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# File 'lib/sequel/database/schema_methods.rb', line 285

def create_view(name, source, options = OPTS)
  execute_ddl(create_view_sql(name, source, options))
  remove_cached_schema(name)
  nil
end

#database_type ⇒ Object

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

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



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# File 'lib/sequel/database/connecting.rb', line 170

def database_type
  adapter_scheme
end

#dataset ⇒ Object

Returns a blank dataset for this database.

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



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

def dataset
  @dataset_class.new(self)
end

#disconnect(opts = OPTS) ⇒ Object

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

:servers

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

Example:

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



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# File 'lib/sequel/database/connecting.rb', line 184

def disconnect(opts = OPTS)
  pool.disconnect(opts)
end

#disconnect_connection(conn) ⇒ Object

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.



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# File 'lib/sequel/database/connecting.rb', line 191

def disconnect_connection(conn)
  conn.close
end

#drop_column(table, *args) ⇒ Object

Removes a column from the specified table:

DB.drop_column :items, :category

See alter_table.



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# File 'lib/sequel/database/schema_methods.rb', line 296

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

#drop_index(table, columns, options = OPTS) ⇒ Object

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

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

See alter_table.



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# File 'lib/sequel/database/schema_methods.rb', line 306

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

#drop_join_table(hash, options = OPTS) ⇒ Object

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

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



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# File 'lib/sequel/database/schema_methods.rb', line 315

def drop_join_table(hash, options=OPTS)
  drop_table(join_table_name(hash, options), options)
end

#drop_table(*names) ⇒ Object

Drops one or more tables corresponding to the given names:

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



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# File 'lib/sequel/database/schema_methods.rb', line 324

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

#drop_table?(*names) ⇒ Boolean

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

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

Returns:

  • (Boolean) 


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# File 'lib/sequel/database/schema_methods.rb', line 339

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

#drop_view(*names) ⇒ Object

Drops one or more views corresponding to the given names:

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



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# File 'lib/sequel/database/schema_methods.rb', line 366

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

#each_server(&block) ⇒ Object

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

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

Raises:



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# File 'lib/sequel/database/connecting.rb', line 200

def each_server(&block)
  raise(Error, "Database#each_server must be passed a block") unless block
  servers.each{|s| self.class.connect(server_opts(s), &block)}
end

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

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



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

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

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

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



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

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

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

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



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# File 'lib/sequel/database/query.rb', line 56

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

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

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

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

Examples:

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

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

Raises:



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# File 'lib/sequel/database/dataset_defaults.rb', line 81

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

#extension(*exts) ⇒ Object

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.



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

def extension(*exts)
  Sequel.extension(*exts)
  exts.each do |ext|
    if pr = Sequel.synchronize{EXTENSIONS[ext]}
      pr.call(self)
    else
      raise(Error, "Extension #{ext} does not have specific support handling individual databases (try: Sequel.extension #{ext.inspect})")
    end
  end
  self
end

#fetch(sql, *args, &block) ⇒ Object

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

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

The fetch method returns a dataset instance:

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

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

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



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# File 'lib/sequel/database/dataset.rb', line 44

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

#from(*args, &block) ⇒ Object

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

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



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

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

#from_application_timestamp(v) ⇒ Object

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



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# File 'lib/sequel/database/misc.rb', line 211

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

#get(*args, &block) ⇒ Object

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

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



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

def get(*args, &block)
  @default_dataset.get(*args, &block)
end

#global_index_namespace? ⇒ Boolean

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

Returns:

  • (Boolean) 


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# File 'lib/sequel/database/features.rb', line 11

def global_index_namespace?
  true
end

#in_transaction?(opts = OPTS) ⇒ Boolean

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

Returns:

  • (Boolean) 


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# File 'lib/sequel/database/misc.rb', line 218

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

#inspect ⇒ Object

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



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# File 'lib/sequel/database/misc.rb', line 224

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

#literal(v) ⇒ Object

Proxy the literal call to the dataset.

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



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# File 'lib/sequel/database/misc.rb', line 238

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

#literal_symbol(sym) ⇒ Object

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



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# File 'lib/sequel/database/misc.rb', line 244

def literal_symbol(sym)
  Sequel.synchronize{@symbol_literal_cache[sym]}
end

#literal_symbol_set(sym, lit) ⇒ Object

Set the cached value of the literal symbol.



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# File 'lib/sequel/database/misc.rb', line 249

def literal_symbol_set(sym, lit)
  Sequel.synchronize{@symbol_literal_cache[sym] = lit}
end

#log_exception(exception, message) ⇒ Object

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



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

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

#log_info(message, args = nil) ⇒ Object

Log a message at level info to all loggers.



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

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

#log_yield(sql, args = nil) ⇒ Object

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



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# File 'lib/sequel/database/logging.rb', line 32

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

#logger=(logger) ⇒ Object

Remove any existing loggers and just use the given logger:

DB.logger = Logger.new($stdout)



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

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

#prepared_statement(name) ⇒ Object

Synchronize access to the prepared statements cache.



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# File 'lib/sequel/database/misc.rb', line 254

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

#quote_identifier(v) ⇒ Object

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



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# File 'lib/sequel/database/misc.rb', line 261

def quote_identifier(v)
  schema_utility_dataset.quote_identifier(v)
end

#quote_identifiers=(v) ⇒ Object

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

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



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# File 'lib/sequel/database/dataset_defaults.rb', line 119

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

#quote_identifiers? ⇒ Boolean

Returns true if the database quotes identifiers.

Returns:

  • (Boolean) 


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

def quote_identifiers?
  @quote_identifiers
end

#remove_servers(*servers) ⇒ Object

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

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

DB.remove_servers(:f1, :f2)



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# File 'lib/sequel/database/connecting.rb', line 215

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

#rename_column(table, *args) ⇒ Object

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

DB.rename_column :items, :cntr, :counter

See alter_table.



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# File 'lib/sequel/database/schema_methods.rb', line 392

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

#rename_table(name, new_name) ⇒ Object

Renames a table:

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



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# File 'lib/sequel/database/schema_methods.rb', line 380

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

#run(sql, opts = OPTS) ⇒ Object

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

:server

The server to run the SQL on.

DB.run("SET some_server_variable = 42")



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

def run(sql, opts=OPTS)
  sql = literal(sql) if sql.is_a?(SQL::PlaceholderLiteralString)
  execute_ddl(sql, opts)
  nil
end

#schema(table, opts = OPTS) ⇒ Object

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

:reload

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

:schema

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

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

:allow_null

Whether NULL is an allowed value for the column.

:db_type

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

:default

The database default for the column, as a database specific string, 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}]]

Raises:



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# File 'lib/sequel/database/query.rb', line 121

def schema(table, opts=OPTS)
  raise(Error, 'schema parsing is not implemented on this database') unless supports_schema_parsing?

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

  qualifiers = split_qualifiers(tab)
  table_name = qualifiers.pop
  sch = qualifiers.pop
  information_schema_schema = case qualifiers.length
  when 1
    Sequel.identifier(*qualifiers)
  when 2
    Sequel.qualify(*qualifiers)
  end

  if table.is_a?(Dataset)
    quoted_name = table.literal(tab)
    opts[:dataset] = table
  else
    quoted_name = schema_utility_dataset.literal(table)
  end

  opts[:schema] = sch if sch && !opts.include?(:schema)
  opts[:information_schema_schema] = information_schema_schema if information_schema_schema && !opts.include?(:information_schema_schema)

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

  cols = schema_parse_table(table_name, opts)
  raise(Error, 'schema parsing returned no columns, table probably doesn\'t exist') if cols.nil? || cols.empty?

  primary_keys = 0
  auto_increment_set = false
  cols.each do |_,c|
    auto_increment_set = true if c.has_key?(:auto_increment)
    primary_keys += 1 if c[:primary_key]
  end

  cols.each do |_,c|
    c[:ruby_default] = column_schema_to_ruby_default(c[:default], c[:type]) unless c.has_key?(:ruby_default)
    if c[:primary_key] && !auto_increment_set
      # If adapter didn't set it, assume that integer primary keys are auto incrementing
      c[:auto_increment] = primary_keys == 1 && !!(c[:db_type] =~ /int/io)
    end
    if !c[:max_length] && c[:type] == :string && (max_length = column_schema_max_length(c[:db_type]))
      c[:max_length] = max_length
    end
  end
  Sequel.synchronize{@schemas[quoted_name] = cols} if cache_schema
  cols
end

#schema_type_class(type) ⇒ Object

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



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# File 'lib/sequel/database/misc.rb', line 266

def schema_type_class(type)
  @schema_type_classes[type]
end

#select(*args, &block) ⇒ Object

Returns a new dataset with the select method invoked.

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



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

def select(*args, &block)
  @default_dataset.select(*args, &block)
end

#serial_primary_key_options ⇒ Object

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



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# File 'lib/sequel/database/misc.rb', line 272

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

#servers ⇒ Object

An array of servers/shards for this Database object.

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



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# File 'lib/sequel/database/connecting.rb', line 226

def servers
  pool.servers
end

#set_column_default(table, *args) ⇒ Object

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

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

See alter_table.



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# File 'lib/sequel/database/schema_methods.rb', line 401

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

#set_column_type(table, *args) ⇒ Object

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

DB.set_column_type :items, :price, :float

See alter_table.



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# File 'lib/sequel/database/schema_methods.rb', line 410

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

#set_prepared_statement(name, ps) ⇒ Object

Cache the prepared statement object at the given name.



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# File 'lib/sequel/database/misc.rb', line 277

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

#sharded? ⇒ Boolean

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

Returns:

  • (Boolean) 


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# File 'lib/sequel/database/misc.rb', line 284

def sharded?
  @sharded
end

#single_threaded? ⇒ Boolean

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

Returns:

  • (Boolean) 


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# File 'lib/sequel/database/connecting.rb', line 231

def single_threaded?
  @single_threaded
end

#supports_create_table_if_not_exists? ⇒ Boolean

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

Returns:

  • (Boolean) 


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# File 'lib/sequel/database/features.rb', line 17

def supports_create_table_if_not_exists?
  false
end

#supports_deferrable_constraints? ⇒ Boolean

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

Returns:

  • (Boolean) 


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# File 'lib/sequel/database/features.rb', line 23

def supports_deferrable_constraints?
  false
end

#supports_deferrable_foreign_key_constraints? ⇒ Boolean

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

Returns:

  • (Boolean) 


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# File 'lib/sequel/database/features.rb', line 29

def supports_deferrable_foreign_key_constraints?
  supports_deferrable_constraints?
end

#supports_drop_table_if_exists? ⇒ Boolean

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

Returns:

  • (Boolean) 


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# File 'lib/sequel/database/features.rb', line 35

def supports_drop_table_if_exists?
  supports_create_table_if_not_exists?
end

#supports_foreign_key_parsing? ⇒ Boolean

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

Returns:

  • (Boolean) 


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# File 'lib/sequel/database/features.rb', line 41

def supports_foreign_key_parsing?
  respond_to?(:foreign_key_list)
end

#supports_index_parsing? ⇒ Boolean

Whether the database supports Database#indexes for parsing indexes.

Returns:

  • (Boolean) 


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# File 'lib/sequel/database/features.rb', line 46

def supports_index_parsing?
  respond_to?(:indexes)
end

#supports_partial_indexes? ⇒ Boolean

Whether the database supports partial indexes (indexes on a subset of a table).

Returns:

  • (Boolean) 


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# File 'lib/sequel/database/features.rb', line 51

def supports_partial_indexes?
  false
end

#supports_prepared_transactions? ⇒ Boolean

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

Returns:

  • (Boolean) 


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# File 'lib/sequel/database/features.rb', line 57

def supports_prepared_transactions?
  false
end

#supports_savepoints? ⇒ Boolean

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

Returns:

  • (Boolean) 


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# File 'lib/sequel/database/features.rb', line 62

def supports_savepoints?
  false
end

#supports_savepoints_in_prepared_transactions? ⇒ Boolean

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

Returns:

  • (Boolean) 


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# File 'lib/sequel/database/features.rb', line 68

def supports_savepoints_in_prepared_transactions?
  supports_prepared_transactions? && supports_savepoints?
end

#supports_schema_parsing? ⇒ Boolean

Whether the database supports schema parsing via Database#schema.

Returns:

  • (Boolean) 


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# File 'lib/sequel/database/features.rb', line 73

def supports_schema_parsing?
  respond_to?(:schema_parse_table, true)
end

#supports_table_listing? ⇒ Boolean

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

Returns:

  • (Boolean) 


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# File 'lib/sequel/database/features.rb', line 78

def supports_table_listing?
  respond_to?(:tables)
end

#supports_transaction_isolation_levels? ⇒ Boolean

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

Returns:

  • (Boolean) 


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# File 'lib/sequel/database/features.rb', line 88

def supports_transaction_isolation_levels?
  false
end

#supports_transactional_ddl? ⇒ Boolean

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

Returns:

  • (Boolean) 


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# File 'lib/sequel/database/features.rb', line 93

def supports_transactional_ddl?
  false
end

#supports_view_listing? ⇒ Boolean

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

Returns:

  • (Boolean) 


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# File 'lib/sequel/database/features.rb', line 83

def supports_view_listing?
  respond_to?(:views)
end

#supports_views_with_check_option? ⇒ Boolean

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

Returns:

  • (Boolean) 


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# File 'lib/sequel/database/features.rb', line 98

def supports_views_with_check_option?
  !!view_with_check_option_support
end

#supports_views_with_local_check_option? ⇒ Boolean

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

Returns:

  • (Boolean) 


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# File 'lib/sequel/database/features.rb', line 103

def supports_views_with_local_check_option?
  view_with_check_option_support == :local
end

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

:nocov:



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# File 'lib/sequel/database/connecting.rb', line 248

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

#table_exists?(name) ⇒ Boolean

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

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

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

Returns:

  • (Boolean) 


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# File 'lib/sequel/database/query.rb', line 191

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

#test_connection(server = nil) ⇒ Object

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



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# File 'lib/sequel/database/connecting.rb', line 263

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

#to_application_timestamp(v) ⇒ Object

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



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# File 'lib/sequel/database/misc.rb', line 296

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

#transaction(opts = OPTS, &block) ⇒ Object

Starts a database transaction. When a database transaction is used, either all statements are successful or none of the statements are successful. Note that MySQL MyISAM 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.

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+).



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# File 'lib/sequel/database/transactions.rb', line 78

def transaction(opts=OPTS, &block)
  if retry_on = opts[:retry_on]
    tot_retries = opts.fetch(:num_retries, 5)
    num_retries = 0 unless tot_retries.nil?
    begin
      transaction(Hash[opts].merge!(:retry_on=>nil, :retrying=>true), &block)
    rescue *retry_on => e
      if num_retries
        num_retries += 1
        if num_retries <= tot_retries
          opts[:before_retry].call(num_retries, e) if opts[:before_retry]
          retry
        end
      else
        retry
      end
      raise
    end
  else
    synchronize(opts[:server]) do |conn|
      if already_in_transaction?(conn, opts)
        if opts[:retrying]
          raise Sequel::Error, "cannot set :retry_on options if you are already inside a transaction"
        end
        if opts[:savepoint] != false && (stack = _trans(conn)[:savepoints]) && stack.last
          _transaction(conn, Hash[opts].merge!(:savepoint=>true), &block)
        else
          return yield(conn)
        end
      else
        _transaction(conn, opts, &block)
      end
    end
  end
end

#typecast_value(column_type, value) ⇒ Object

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



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# File 'lib/sequel/database/misc.rb', line 305

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

#uri ⇒ Object

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



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# File 'lib/sequel/database/misc.rb', line 317

def uri
  opts[:uri]
end

#url ⇒ Object

Explicit alias of uri for easier subclassing.



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# File 'lib/sequel/database/misc.rb', line 322

def url
  uri
end

#valid_connection?(conn) ⇒ Boolean

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.

Returns:

  • (Boolean) 


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# File 'lib/sequel/database/connecting.rb', line 272

def valid_connection?(conn)
  sql = valid_connection_sql
  begin
    log_connection_execute(conn, sql)
  rescue Sequel::DatabaseError, *database_error_classes
    false
  else
    true
  end
end