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 3.31.0 has been released and should be available on the gem
= New Features
The serialization plugin can now support custom serialization
formats, by supplying a serializer/deserializer pair of
callable objects. You can also register custom deserializers
via Sequel::Plugins::Serialization.register_format, so that
they can be referenced by name. Example:
class User < Sequel::Model
serialize_attributes :reverse, :password
Dataset#import and #multi_insert now support a
:return=>:primary_key option. When this option is used, the
methods return an array of primary key values, one for each
inserted row. Usage of this option on MySQL requires that a
separate query be issued per row (instead of the single
query for all rows that MySQL would usually use).
PostgreSQL can now use Dataset#returning in conjunction with
import/multi_insert to set a custom column to return.
Microsoft SQL Server can now use Dataset#output in conjection with
import/multi_insert to set a custom column to return.
Dataset#import and #multi_insert now respect a :server option to
set the server/shard on which to execute the queries.
Additionally, options given to this method are also passed to
Dataset#insert_multiple now returns an array of inserted primary
Model.def_column_alias has been added to make it easy to create
alias methods for columns. This is useful if you have a legacy
database and want to create friendly method names for the
underlying columns. Note that this alias only affects the setter
and getter methods. This does not affect the dataset level, so you
still need to use the actual column names in dataset filters.
many_to_one associations can now have the same name as the related
foreign key column, using the :key_column option. Use of this
feature is not recommended, as it is much better to either rename
the column or rename the association. Here’s an example of usage:
:id /–> :id
:artist --/ :name
class Album < Sequel::Model
many_to_one :artist, :key_column=>:artist
The mock adapter can now mock out database types, by providing a
shared adapter name as the host (e.g. mock://postgres). This
emulation is not perfect, but in most cases it allows you to see
what SQL Sequel would generate on a given database without needing
to install the required database driver.
Sequel now supports creating full text indexes on Microsoft SQL
Server. Before using it, you must have previously setup a default
full text search catalog, and you need to provide a :key_index
option with an index name symbol.
Dataset#group_rollup and #group_cube methods have been added for
GROUP BY ROLLUP and GROUP BY CUBE support. These features are in
a recent SQL standard, and they are supported to various degrees on
Microsoft SQL Server, DB2, Oracle, MySQL, and Derby.
Dataset#full_text_search on Microsoft SQL Server now supports
multiple search terms.
The jdbc adapter now supports a :login_timeout option, giving the
timeout in seconds.
= Other Improvements
Dataset#exists can now be used with prepared statement
Dataset#full_text_search can now be used with prepared statement
placeholders on PostgreSQL, MySQL, and Microsoft SQL Server.
If tables from two separate schema are detected when parsing the
schema for a table on PostgreSQL, an error is now raised.
Previously, no error was raised, which led to weird errors later,
such as duplicate columns in a model’s primary_key.
RETURNING is now supported with UPDATE/DELETE on PostgreSQL 8.2+.
Previously, Sequel only supported it on 9.1+, but PostgreSQL
introduced support for it in 8.2.
The shared postgres adapter now correctly handles the return value
for Dataset#insert if you provide a separate column array and value
array on PostgreSQL < 8.2.
Handle case in the PostgreSQL adapter where the server version
cannot be determined via a query.
H2 clob types are now treated as string instead of as blob.
Treating clob as blob breaks on H2, as it doesn’t automatically
hex-unescape the input for clobs as it does for blobs.
Dataset#empty? now works correctly when the dataset has an offset
and offset support is being emulated.
The mock adapter no longer defaults to downcasing identifiers on
= Backwards Compatibility
Dataset#exists now returns a PlaceholderLiteralString instead of a
LiteralString, which could potentially break some code. If you
would like a String returned, you can pass the returned object to
Dataset#from no longer handles :a__b__c___d as “a.b.c AS d”. This
was not the intended behavior, and nowhere else in Sequel is a
symbol treated that way. Now, Dataset#from is consistent with the
rest of Sequel, using “a.b__c AS d”. This should only affect
people in very rare cases, as most databases don’t use three level
qualified tables. One exception is Microsoft SQL Server, which can
use three level qualified tables for cross-database access.
Previously, Dataset#insert_multiple returned an array of hashes, now
it returns an array of primary key values.
Dataset#EXRACT_CLOSE in the shared sqlite adapter has been renamed to
Dataset::ArgumentMapper::SQL_QUERY_TYPE constants have been removed,
as have related sql_query_type private methods.
The serialization plugin was significantly refactored.
Model.serialization_map now contains a callable object instead of a
Symbol, and Model.serialization_format has been removed.
Model.define_serialized_attribute_accessors private method now takes
two callable objects before the columns, instead of a single symbol.