Version 1.6.0

  * New concept, view, is a C++ class that embodies a light-weight, read-
    only projection of one or more persistent objects or database tables
    or the result of a native SQL query execution. Some of the common
    applications of views include loading a subset of data members from
    objects or columns from database tables, executing and handling
    results of arbitrary SQL queries, including aggregate queries, as
    well as joining multiple objects and/or database tables using object
    relationships or custom join conditions. For more information refer
    to Chapter 9, "Views" in the ODB manual as well as the 'view' example
    in the odb-examples package.

  * New function, database::erase_query(), allows the deletion of the
    database state of multiple objects matching certain criteria. It uses
    the same query expression as the database::query() function. For more
    information, refer to Section 3.10, "Deleting Persistent Objects" in
    the ODB manual.

  * Support for value wrappers. An ODB value wrapper is a class template
    that wraps a value type or a container. Common examples of wrappers
    are smart pointers, holders, and "optional value" containers such as
    boost::optional. A wrapper can be transparent or it can handle the
    NULL semantics. To allow the easy conversion of value types that do
    not support the NULL semantics into the ones that do, the odb::nullable
    class template has been added. ODB now also includes built-in support for
    std::auto_ptr and std::tr1::shared_ptr smart pointers as value wrappers
    as well as for boost::shared_ptr and QSharedPointer via the Boost and Qt
    profiles. Currently, the NULL semantics is only supported for simple
    values but smart pointers can still be used with composite values and
    containers. For more information, refer to Section 7.3, "NULL Value
    Semantics" in the ODB manual.

  * Support for the boost::optional container in the Boost profile. A data
    member of the boost::optional type is mapped to a column that can have
    a NULL value. For more information, refer to Section 15.3 "Optional
    Library" in the ODB manual.

  * Support for mapping std::vector<char> to the BLOB (or equivalent) types.
    For more information, refer to Chapters 11 (for MySQL), 12 (for SQLite)
    and 13 (for PostgreSQL) in the ODB manual.

  * New option, --table-prefix, allows the specification of a prefix that
    is added to table and index names. For more information, refer to the
    ODB compiler command line interface documentation (man pages).

  * New ODB runtime library interface, odb::connection, represents a
    connection to the database. The primary use case for a connection is to
    execute native statements outside of a transaction. For more information,
    refer to Section 3.5, "Connections" in the ODB manual.

  * Support for multiplexing several transactions on the same thread. For
    more information, refer to Section 3.4, "Transactions" in the ODB
    manual.

  * All the concrete connection classes now have a second constructor which
    allows the creation of a connection instance from an already established
    underlying connection handle. The connection_pool_factory and, in case of
    SQLite, single_connection_factory now have a virtual create() function
    that can be overridden to implement custom connection establishment and
    configuration.

  * The query expression syntax for object pointers and composite values has
    changed. Now, instead of using the scope resolution operator ('::'), the
    member access via a pointer operator (->) is used for object pointers and
    the member access operator (.) is used for composite values. Examples of
    old and new syntax for pointers, old: query<employee>::employer::name,
    new: query<employee>::employer->name. For composites values, old:
    query<employee>::name::first, new: query<employee>::name.first.

  * SQLite ODB runtime now enables foreign key constraints checking by
    default. While this should not affect correct applications, due to
    bugs in SQLite DDL foreign keys support, you may need to temporarily
    disable foreign key constraints checking when re-creating the database
    schema (the sign that you may need to do so is the "foreign key
    constraint failed" exception thrown by the commit() function after the
    call to schema_catalog::create_schema()). For more information, refer
    to Section 12.5.3, "Foreign Key Constraints" in the ODB manual.

  * Support for specifying the client character set for the MySQL database.
    For more information, refer to Section 11.2, "MySQL Database Class" in
    the ODB manual.

  * Object cache maintained by a session no longer distinguishes between
    const and non-const objects. Instead, const objects are treated as
    non-const by casting away constness. For more information on this new
    behavior, refer to Section 9.1, "Object Cache" in the ODB manual.

Version 1.5.0

  * Support for the PostgreSQL database. The provided connection factories
    include 'new' (a new connection is created every time one is requested)
    and 'pool' (a pool of connections is maintained). The Boost and Qt
    profiles have been updated to support this database. For more information,
    refer to Chapter 13, "PostgreSQL Database" in the ODB manual.

  * New handling of the NULL semantics. Now, instead of being specified as
    part of the SQL type with the type pragma, there are separate null and
    not_null pragmas. The not_null pragma was used to control the NULL
    semantics of object pointers. Now the two pragmas are used consistently
    for object pointers and simple values (and, in the future, they will work
    for composite values and containers). To control the NULL semantics of
    the container's element values, the value_null and value_not_null pragmas
    have been added, similar to the value_type, value_column, etc., pragmas.
    For more information about the new mechanism, refer to Sections 10.2.3,
    10.2.8, 10.3.4, and 10.3.13 in the ODB manual.

    This is a backwards-incompatible change. Existing use cases that will
    require manual changes are listed below.

    For pragmas that apply to simple value types and data members of
    such types:

    #pragma db type("TEXT NOT NULL") => #pragma db type("TEXT")
    #pragma db type("TEXT NULL")     => #pragma db type("TEXT") null
    #pragma db type("TEXT")          => #pragma db type("TEXT") null

    For pragmas that apply to containers of pointers and data members of
    such types:

    #pragma db not_null              => #pragma db value_not_null

  * New pragma, default, allows the specification of the database default
    value. For more information, refer to Section 10.3.5, "default" in the
    ODB manual.

  * New pragmas, options, id_options, index_options, key_options, and
    value_options, allow the specification of additional column definition
    options. For more information, refer to Section 10.3.6, "options" in
    the ODB manual.

  * Support for database operations callbacks. Now a persistent class can
    register a callback function that will be called before and after every
    database operation (such as persist, load, update, or erase) is performed
    on an object of this class. A database operations callback can be used to
    implement object-specific pre and post initializations, registrations,
    and cleanups. For more information and an example, refer to Section
    10.1.4, "callback" in the ODB manual.

  * New option, --include-regex, allows the modification of the #include
    directive paths generated by the ODB compiler. This is primarily useful
    when placing the generated code into subdirectories and the #include
    directives have to be adjusted accordingly. The --include-regex-trace
    option is useful for debugging the expressions specified with
    --include-regex.

Version 1.4.0

  * New profile, qt, provides persistence support for the Qt framework. This
    version covers the most commonly used basic types, date-time types, smart
    pointers, and containers. The qt profile implementation is provided by the
    libodb-qt library. For more information refer to Chapter 13, "Profiles
    Introduction" and Chapter 15, "Qt Profile" in the ODB manual as well as
    the 'qt' example in the odb-examples package.

  * Support for non-polymorphic object inheritance, including the new abstract
    pragma. For more information refer to Chapter 8, "Inheritance" in the ODB
    manual as well as the 'inheritance' example in the odb-examples package.

  * Automatic mapping of C++ enumerations to suitable database types. In
    database systems that support enumeration types (such as MySQL), a C++
    enum is mapped to such a type (for example, ENUM('red', 'green', 'blue')
    in MySQL). Otherwise, it is mapped to a suitable integer type. Refer to
    Part II, "Database Systems" in the ODB manual for more details on the
    provided mappings.

  * New pragma, id_type, allows the specification of the native database type
    that should be used for data members designated as object identifiers. In
    combination with the type pragma, id_type allows you to map a C++ type
    differently depending on whether it is used in an ordinary member or an
    object id.

  * New options, --odb-prologue-file and --odb-epilogue-file, allow the
    inclusion of file contents into the ODB compilation.

  * Default mapping of the size_t and std::size_t types to a 64-bit integer
    database type irrespective of the platform width. This can be overridden
    with the type pragma.

Version 1.3.0

  * Support for the SQLite database. The provided connection factories include
    'new' (a new connection is created every time one is requested), 'single'
    (single connection is shared among all the callers), and 'pool' (a pool
    of connections is maintained). In multi-threaded applications the runtime
    uses the SQLite shared cache and unlock notification features to aid
    concurrency. For more information, refer to Chapter 11, "SQLite Database"
    in the ODB manual.

  * Support for database-specific profiles. Now the ODB compiler first looks
    for the <profile>-<database>.options file and only if this file is not
    found, does it fall back to <profile>.options.

  * Support for the GCC 4.6 plugin interface changes.

Version 1.2.0

  * New profile, boost, provides persistence support for the Boost libraries.
    This version covers the most commonly used types from the smart_ptr,
    unordered, and date_time libraries. The boost profile implementation is
    provided by the libodb-boost library. For more information refer to
    Chapter 11, "Profiles Introduction" and Chapter 12, "Boost Profile" in
    the ODB manual as well as the 'boost' example in the odb-examples package.

  * Support for embedded database schemas. The new option, --schema-format,
    allows the selection of the schema format. The valid values for this
    option are 'sql' for a standalone SQL file and 'embedded' for a schema
    embedded into the generated C++ code. The new odb::schema_catalog class
    provides support for accessing embedded schemas from within the
    application. For details refer to Section 3.3, "Database" in the ODB
    manual as well as the 'schema/embedded' example in the odb-examples
    package.

  * New exceptions: odb::recoverable, odb::connection_lost, and odb::timeout.
    The odb::recoverable exception is a common base class for all recoverable
    ODB exceptions. The other two exceptions plus odb::deadlock now inherit
    from this base. Refer to Section 3.5, "Error Handling and Recovery" for
    details.

  * Support for connection validation (ping) in MySQL connection_pool_factory.
    This transparently deals with the MySQL server closing connections after
    a certain period of inactivity.

  * New namespace, odb::core, contains using-declarations for the core ODB
    constructs, such as the database, transaction, etc. The primary use of
    this namespace is in the using-directives:

    using namespace odb::core;

    The above form should be preferred over the old variant:

    using namespace odb;

    The new approach brings all the essential ODB names into the current
    namespace without any of the auxiliary objects such as traits, etc., which
    minimizes the likelihood of conflicts with other libraries.  Note that you
    should still use the odb namespace when qualifying individual names, for
    example, odb::database.

  * New option aliases: -q for --generate-query and -s for --generate-schema.

  * Support for the default options file. Now, if configured, the ODB compiler
    loads the default options file (by default ../etc/odb/default.options,
    relative to the ODB compiler binary). This file can be used for
    installation-wide customization, such as adding extra include search
    paths.

Version 1.1.0

  * Support for storing containers in the database. For more information refer
    to Chapter 5, "Containers" in the ODB manual as well as the 'container'
    example in the odb-examples package.

  * Support for unidirectional and bidirectional object relationships,
    including lazy loading. For more information refer to Chapter 6,
    "Relationships" in the ODB manual as well as the 'relationship' and
    'inverse' examples in the odb-examples package.

  * Support for composite value types. For more information refer to Chapter
    7, "Composite Value Types" in the ODB manual as well as the 'composite'
    example in the odb-examples package.

  * Support for sessions. A session is an application's unit of work that
    may encompass several database transactions. In this version of ODB a
    session is just an object cache. For more information refer to Chapter
    8, "Session" in the ODB manual.

  * Support for custom object pointers that allows you to use smart pointers
    to return, pass, and cache persistent objects. See Section 3.2, "Object
    Pointers" in the ODB manual for details.

  * Support for native SQL statement execution. See Section 3.9, "Executing
    Native SQL Statements" in the ODB manual for details.

  * New option, --profile/-p, instructs the ODB compiler to use the specified
    profile library. See the ODB compiler command line manual for details.

  * Support for literal names (template-id, derived type declarator such as
    pointers, etc) in data member declarations. Now, for example, you can use
    std::vector<std::string> directly instead of having to create a typedef
    alias for it.

  * Support for inheritance from transient base types for object types and
    composite value types.

  * New example, 'schema/custom', shows how to map persistent C++ classes to
    a custom database schema.

  * New options, --odb-prologue, --odb-epilogue, allow inclusion of extra code
    into the ODB compilation process. This can be useful for making additional
    traits specializations or ODB pragmas known to the ODB compiler.

  * Support for persistent classes without default constructors. For objects
    of such classes only the load() and find() database functions that
    populate an existing instance can be used. Similarly, only the load()
    query result iterator function which populates an existing instance can
    be used.

Version 1.0.0

  * Initial release.
