* Sequel provides thread safety, connection pooling and a concise DSL
for constructing database queries and table schemas.
* Sequel also includes a lightweight but comprehensive ORM layer for
mapping records to Ruby objects and handling associated records.
* Sequel supports advanced database features such as prepared
statements, bound variables, master/slave configurations, and
database sharding.
* Sequel makes it easy to deal with multiple records without having
to break your teeth on SQL.
* Sequel currently has adapters for ADO, DB2, DBI, Informix, JDBC,
MySQL, ODBC, OpenBase, Oracle, PostgreSQL and SQLite3.
Sequel 2.7.0 has been released and should be available on the gem
mirrors. The 2.7.0 release adds numerous improvements:
Performance Optimizations
···
-------------------------
* Fetching a large number of records with the PostgreSQL adapter is
significantly faster (up to 3-4 times faster than before).
* Instantiating model objects has been made much faster, as many
options (such as raise_on_save_failure) are now lazily loaded, and
hook methods are now much faster if no hooks have been defined for
that type of hook.
New Association Options
-----------------------
* The :eager_grapher option has been added allowing you to supply
your own block to implement eager loading via eager_graph.
* many_to_one and one_to_many associations now have a :primary_key
option, specifying the name of the column that the :key option
references.
* many_to_many associations now have :left_primary_key and
:right_primary_key options, specifying the columns that :left_key
and :right_key reference, respectively.
* many_to_many associations now have a :uniq option, that adds an
:after_load callback that makes the returned array of objects
unique.
Other New Features
------------------
* Dataset#set_graph_aliases now allows you to supply a third argument
for each column you want graph into the dataset, allowing you to use
arbitrary SQL expressions that are graphed into the correct table:
ds.set_graph_aliases!(:a=>[:b, :c], :d=>[:e, :f, 42])
# SELECT b.c AS a, 42 AS d FROM ...
ds.first # => {:b=>{:c=>?}, :e=>{:f=>42}}
* Dataset#add_graph_aliases was added, that adds additional graph
aliases instead of replacing the existing ones (as
#set_graph_aliases does). It's basically the equivalent of
select_more for graphs.
* Dataset#join_table changed it's final argument from a symbol
specifying a table name to an option hash (with backwards
compatibility kept), and adds support for a :implicit_qualifier
option, which it uses instead of the last joined table to
qualify columns.
* Association's :after_load callbacks are now called when eager
loading via eager (but not when eager loading via eager_graph).
* Any expression can now be used as the argument to Symbol#like,
which means that you can pattern match columns to other columns.
Before, it always transformed the argument to a string.
:a.like(:b)
# 2.6.0: a LIKE 'b'
# 2.7.0: a LIKE b
* Array#sql_array was added, allowing you to specify that an array
in ruby be treated like an array in SQL. This is true anyway,
except for arrays of all two pairs, which are treated like hashes,
for specifying multiple conditions with the same key:
DB[:foo].filter([:a,:b] => [[1,2],[3,4]].sql_array)
# => SELECT * FROM foo WHERE ((a, b) IN ((1, 2), (3, 4)))
* ComplexExpression#== and #sql? were added, allowing for easier
testing.
* Full text searching on PostgreSQL now joins multiple columns with
a space, to prevent joining border words, and it works when there
is a match in one column but the other column is NULL.
Other Improvements
------------------
* Instance methods added by creating associations are added to an
anonymous module included by the class, so they can be overridden
in the class while still allowing the use of super to get the
default behavior (this is similar to column accessor methods).
* Many improvements were added to support using multiple schemas in
PostgreSQL.
* Model::Validation::Errors objects are now more compatible with
Rails, by adding a #count method and making #on return nil if there
are no error messages for that attribute.
* Serialized columns in models are no longer typecast.
* Associations are now inherited when a model class is subclassed.
* Many improvements were made that should make adding custom
association types easier.
* A corner case in eager_graph where the wrong table name would be
used to qualify a column name has been fixed.
* Dataset's cached column information is no longer modified if #each
is called with an option that modifies the columns.
* You should now be able to connect to Oracle via the JDBC adapter,
and with the same support it has when using the oracle adapter.
* Model.association_reflections is now a public methods, so you can
grab a hash of all association reflections at once (keyed by
association name symbol).
* The :encoding/:charset option now works in the PostgreSQL adapter
if the postgres-pr driver is used.
* The numeric(x,y) type is now interpreted as decimal.
Backwards Compatibilty
----------------------
* The first argument to Model#initialize must be a hash, you can no
longer use nil. For example, the following code will break if
:album is not in params:
Album.new(params[:album])
Additionally, Model#initialize does not call the block if the
second argument is true.
* The Sequel::Model.lazy_load_schema setting was removed. It should
no longer be necessary now that schema loading is relatively speedy,
and schemas can be loaded at startup and cached.
* The PostgreSQL adapter will default to using a unix socket in /tmp
if no host is specified. Before, a TCP/IP socket to localhost was
used if no host was specified. This change makes Sequel operate
similarly to the PostgreSQL command line tools.
* The ASSOCIATION_TYPES constant has changed from an array to a hash
and it has been moved. The RECIPROCAL_ASSOCIATIONS constant has
been removed. This is unlikely to matter unless you were using
custom association types.
* The PostgreSQL adapter now sets the PostgreSQL DateStyle, in order
to implement an optimization. To turn this off, set
Sequel::Postgres.use_iso_date_format = false.
* When using the PostgreSQL adapter, in many places the schema is
specified explicitly. If you do not specify a schema, a default
one is used (public by default). If you use a schema other than
public for your work, use Database#default_schema= to set it. For
any table outside of the default schema, you should specify the
schema explicitly, even if it is in the PostgreSQL search_path.
* Model::Validation::Errors#on now returns nil instead of [] if there
are no errors for an attribute.
* Hooks added to a superclass after a subclass has been created no
longer have an effect on the subclass.
* The Postgres.string_to_bool method has been removed.
* PostgreSQL full text searching now always defaults to using the
simple dictionary. If you want to use another dictionary, it must
be specified explicitly, both when searching and when creating a
full text index.
Thanks,
Jeremy
* {Website}[http://sequel.rubyforge.org]
* {Source code}[http://github.com/jeremyevans/sequel]
* {Bug tracking}[http://code.google.com/p/ruby-sequel/issues/list]
* {Google group}[http://groups.google.com/group/sequel-talk]
* {RDoc}[http://sequel.rubyforge.org/rdoc]
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