ANN: Sequel 3.38.0 Released

Sequel is a lightweight database access toolkit for Ruby.

  • Sequel provides thread safety, connection pooling and a concise
    DSL for constructing SQL queries and table schemas.
  • Sequel includes a comprehensive ORM layer for mapping records to
    Ruby objects and handling associated records.
  • Sequel supports advanced database features such as prepared
    statements, bound variables, stored procedures, savepoints,
    two-phase commit, transaction isolation, master/slave
    configurations, and database sharding.
  • Sequel currently has adapters for ADO, Amalgalite, DataObjects,
    DB2, DBI, Firebird, IBM_DB, Informix, JDBC, MySQL, Mysql2, ODBC,
    OpenBase, Oracle, PostgreSQL, SQLite3, Swift, and TinyTDS.

Sequel 3.38.0 has been released and should be available on the gem

= New Features

  • A pg_row extension has been added that supports PostgreSQL’s
    row-valued/composite types. You can register support for
    specific row types:


    Then you can create values of that row type:

    ad = DB.row_type(:address, [‘555 Foo St.’, ‘Bar City’, ‘98765’])


    ad = DB.row_type(:address, :street=>‘555 Foo St.’,
    :city=>‘Bar City’, :zip=>‘98765’)

    Which you can use in your datasets:

    DB[:people].insert(:name=>‘Me’, :address=>ad)

    If you are using the native postgres adapter, when retreiving
    row type values, they will be returned as instances of the row
    type, which are hash-like objects:

    ad = DB[:people].get(:address)
    ad[:street] # => ‘555 Foo St.’
    ad[:city] # => ‘Bar City’
    ad[:zip] # => ‘98765’

    If you are also using the pg_array extension, then arrays of
    composite types are supported automatically. Composite
    types can also include arrays of other types as well as other
    composite types, though recursive composite types are not
    allowed by PostgreSQL.

    Using arrays and composite types brings one of the benefits
    of document databases to PostgreSQL, allowing you to store
    nested structures inside a single row.

  • A pg_row_ops extension has been added that adds DSL support
    for accessing members of row-valued/composite types. You
    first create a row op:

    r = Sequel.pg_row_op(:row_column)

    Then you can get DSL support for accessing members of that
    row_column via the #[] method:

    r[:a] # (row_column).a

    This works with composite types containing composite types:

    r[:a][:b] # ((row_column).a).b

    When used in conjunction with the pg_array_ops extension,
    there is support for composite types that include arrays,
    as well as arrays of composite types:

    r[1][:a] # (row_column[1]).a
    r[:a][1] # (row_column).a[1]

    The extension offers additional support for referencing
    a table’s type when it contains a column with the same
    name, see the RDoc for details.

  • A pg_row plugin has been added, that works with the pg_row
    extension, and allows you to represent row-valued types as
    Sequel::Model objects (instead of the hash-like objects
    they use by default). In your model class, you load the

    class Address < Sequel::Model(:address)
    plugin :pg_row

    Then you can use Address instances in your datasets:

    ad =>‘555 Foo St.’,
    :city=>‘Bar City’, :zip=>‘98765’)
    DB[:people].insert(:name=>‘Me’, :address=>ad)

    And if you are using the native postgres adapter, the dataset
    will return the type as a model instance:

    ad = DB[:people].get(:address)
    ad.street # => ‘555 Foo St.’ # => ‘Bar City’ # => ‘98765’

  • A pg_typecast_on_load plugin has been added. This plugin is
    designed for use with the jdbc/postgres, do/postgres, and
    swift/postgres adapters, and it is similar to the
    typecast_on_load plugin. However, while the typecast_on_load
    plugin uses setter methods, the pg_typecast_on_load plugin
    uses the same code that the native postgres adapter uses for

  • The tinytds adapter now supports a :textsize option to override
    the default TEXTSIZE setting. The FreeTDS default is fairly
    small (~64k), so if you want to use large blob or text columns,
    you should probably set this to a value larger than the
    largest text/blob you want to use.

  • Sequel.expr when called with a symbol now splits the symbol and
    returns an Identifier, QualifiedIdentifier, or AliasedExpression,
    depending on the content of the symbol. Previously, it only
    wrapped the symbol using a Wrapper.

  • Identifier#* and QualifiedIdentifier#* when called without any
    argument now represent a selection of all columns from the
    represented table:

    Sequel.expr(:table).* # table.*
    Sequel.expr(:schema__table).* # schema.table.*

    This makes it easier to represent the selection of all columns
    in a table without using the core extensions.

  • Model#values now has a Model#to_hash alias.

  • SQL::Blob values now have as, cast, and lit methods even if the
    core extensions are not loaded.

= Other Improvements

  • When loading multiple pg_* extensions into a Database instance,
    the conversion procs are only reset once instead of once per

  • All adapters that access PostgreSQL now store type conversion
    procs, similar to the native postgres adapter. This has been
    added to make it easier to write extensions that support
    advanced PostgreSQL types.

  • Database#schema output on PostgreSQL now includes the type oid
    for each column.

  • You can now register custom array types to specific Database
    instances, using the :type_procs and :typecast_methods_module
    options, so it is now possible to have custom array types
    without affecting global state.

  • Dropping of columns with defaults now works correctly on
    Microsoft SQL Server. Before, it would fail as the related
    constraint was not dropped first.

  • The MySQL type “double(x,y)” is now recognized as a float type.

  • The jdbc/jtds and jdbc/derby adapters now handle nil prepared
    statement values in more cases.

  • Blob prepared statement arguments are now handled correctly on
    jdbc/db2 and jdbc/oracle.

  • Sequel now works around a Time#nsec bug in JRuby 1.6 ruby 1.9 mode
    when using Time values in prepared statements in the jdbc adapter.

  • Java::JavaUtil::UUID types are now returned as ruby strings
    when converting types in the jdbc adapter.

  • Real boolean literals are now used on derby 10.7+. On derby <10.7
    Sequel still uses (1 = 1) and (1 != 1) for true and false. This
    allows you to use boolean columns with a true/false default on
    derby 10.7+.

  • Clobs are now treated as string types instead of blobs on derby,
    since treating clob as blob doesn’t work there.

  • The swift adapter now supports an output identifier method.

  • The swift adapter now returns blobs as SQL::Blob instances.

  • The schema_dumper extension no longer produces code that requires
    the core extensions.

  • All of Sequel’s specs now run without the core extensions loaded,
    ensuring that none of the internals depend on the core extensions.
    The only exception is the specs for the core extensions themselves.

= Backwards Compatibility

  • The pg_* extensions no longer modify core classes if the
    core_extensions extension is not loaded. All methods they added now
    have equivalent methods on the main Sequel module:


  • The Sequel::SQL::IdentifierMethods module has been removed. This
    module was only included in Symbol if the core_extensions were
    enabled. Since it only defined a single method, now the core
    extensions just define that method directly on Symbol.

  • The swift adapter now requires swift-db-{postgres,mysql,sqlite3}
    gems instead of the swift gem. swift/postgres requires
    swift-db-postgres 0.2.0+, swift/sqlite requires swift-db-sqlite
    0.1.2+, and swift/mysql requires swift-db-mysql.

  • Sequel will no longer typecast a string to a PostgreSQL array
    or hstore column in a model column setter. This is because the
    parsers that Sequel uses were designed to support only
    PostgreSQL’s output format. It’s unlikely that a user would
    provide that format for typecasting, and while there aren’t known
    security issues with the parsers, they were not designed to handle
    arbtirary user input, so typecasting from string is no longer
    allowed and will now raise an error.

    The only reason such typecasting was allowed in the first place
    was to work around issues in the jdbc/postgres, do/postgres, and
    swift/postgres adapters, using the the typecast_on_load plugin.
    If you were previously using the typecast_on_load plugin for
    hstore or array columns, you need to switch to using the new
    pg_typecast_on_load plugin.

  • The private get_conversion_procs method in the postgres adapter
    no longer accepts an argument.

  • The Sequel::Postgres::PGArray::DatabaseMethods singleton
    define_array_typecast_method method has been removed. This
    method was designed for internal use.

  • The change to make Sequel.expr split symbols can cause the
    following type of code to break:


    This is because expr now returns an AliasedExpression, which
    doesn’t support the desc method. However, as you can’t
    apply an order to an aliased expression, nobody should be
    relying on this.