hamsterdb Embedded Storage 2.1.4               Sun Aug 11 21:20:54 CEST 2013
(C) Christoph Rupp, chris@crupp.de; http://www.hamsterdb.com

This is the README file of hamsterdb Embedded Storage.

Contents:

1. About

hamsterdb Embedded Storage is a database engine written in C/C++. It is fast,
production-proven and easy to use.

This release moves further into the direction of a key/value engine with
modern column-store features: cache-optimized, compressed data structures,
reduced I/O and even basic schema support.

Variable length keys and keys with duplicates are now stored with a custom
BTree memory layout, which stores a small up-front index in each node.
Unlike previous versions, "extended" keys and duplicate keys are no longer
stored in a separate overflow area (which required additional I/O), but in the
leaf node itself. This improves performance and keeps the file size small.

Also, records can now be stored in the leaf, even if they exceed the size of 8
bytes. For this, users have to specify the record size when creating a
Database (using HAM_PARAM_RECORD_SIZE). It is highly recommended to set the
record size if the record size is always constant.

The file format of 2.1.4 is NOT compatible with 2.1.3 and will remain unstable
for the next or the next two releases. Use ham_export/ham_import to upgrade the
files.

2. Changes

New Features
* Added HAM_PARAM_RECORD_SIZE to specify a fixed record size; if it's small
	enough, the records are stored in the leaf and not in a separately
	allocated blob
* Default Btree node layout for variable length keys can now store
	fixed length records inline if they're small enough (and if duplicate
	keys are disabled)
* Default Btree node layout now also stores duplicate keys inline, even
	if they're > 8 bytes (previous versions stored duplicate keys in a
	separate blob, which required lots of additional I/O)
* Default Btree node layout for variable length keys and duplicate keys
	was completely rewritten and now uses an up-front index in the
	node

Bugfixes
- none

Other Changes
* C++ API: Can now specify HAM_RECORD_USER_ALLOC when retrieving keys
	with ham_db_find
* Removed HAM_DISABLE_VARIABLE_KEYS, HAM_ENABLE_EXTENDED_KEYS; they're no
	longer required. Introduced HAM_KEY_SIZE_UNLIMITED for unlimited/variable
	length keys (the default)


To see a list of all changes, look in the file ChangeLog.

3. Roadmap

- See https://github.com/cruppstahl/hamsterdb/wiki/Roadmap

4. Features

- Very fast sorted B+Tree with variable length keys
- Can run as an in-memory database
- Supports multiple databases in one file
- Supports record number databases ("auto-increment")
- Supports duplicate keys
- Support for logging and recovery
- Support for unlimited number of parallel Transactions
- Support for partial reading/writing of records
- Support for network access (remote databases) via TCP/Protocol Buffers
- Support for transparent AES encryption (using libcrypto)
- Basic schema support for POD types (i.e. uint32, uint64, real32 etc)
- Very fast database cursors
- Configurable page size, cache size and index key size
- Runs on Linux, Unices, Microsoft Windows and other architectures
- Endian-independent file format
- Uses memory mapped I/O for fast disk access (but falls back to read/write if
  mmap is not available)
- Uses 64bit file pointers and supports huge files (>2 GB)
- Easy to use and well-documented
- Supports rudimentary live-reorganization by automatically
  merging freelist entries
- Open source and released under the GPL 2.0 or later
- Wrappers for C++, Java, .NET, Erlang, Ada and others

5. Known Issues/Bugs

None.

6. Compiling

6.1 Linux, MacOS and other Unix systems

To compile hamsterdb Embedded Storage, run ./configure, make, make install.

Run `./configure --help' for more options (i.e. static/dynamic library,
build with debugging symbols etc).

6.2 Microsoft Visual Studio 8

A Solution file is provided for Microsoft Visual C++ 2005:
'win32/hamsterdb.sln'. It compiles a static and a dynamic library.
Please read the README.TXT file in the win32 directory.
All libraries can be downloaded precompiled from the hamsterdb webpage.

To download Microsoft Visual C++ 2005 Express Edition for free, go to
http://msdn.microsoft.com/vstudio/express/visualc/default.aspx.

6.3 Dependencies

On Ubuntu, the following packages are required:
  - libdb-dev (optional)
  - protobuf-compiler
  - libprotobuf-dev
  - libgoogle-perftools-dev
  - libboost-system-dev
  - libboost-thread-dev
  - libboost-dev
  - (libuv needs to be installed from sources - see
      https://github.com/joyent/libuv)

For Windows, precompiled dependencies are available here:
https://github.com/cruppstahl/hamsterdb-alien

7. Testing and Example Code

Make automatically compiles several example programs in the directory
'samples'. To see hamsterdb Embedded Storage in action, just run 'samples/db1'
or any other sample. (or 'win32/out/samples/db1/db1.exe' on Windows platforms).

8. API Documentation

The header files in 'include/ham' have extensive comments. Also, a doxygen
script is available; run 'make doc' to start doxygen. The generated
documentation is also available on the hamsterdb web page.

9. Other Ways to Compile hamsterdb Embedded Storage

If you want to compile hamsterdb without using the provided ./configure
environment, you have to set some preprocessor macros:

DEBUG                   enable debugging output and diagnostic checks (slow!)
HAM_LITTLE_ENDIAN       compile for little endian machines (the default)
HAM_BIG_ENDIAN          compile for big endian machines
HAM_32BIT               compile for 32bit (alias: WIN32)
HAM_64BIT               compile for 64bit (alias: WIN64, also needs WIN32)

Also, if you compile for windows, you have to compile the file
'src/os_win32.cc' and ignore the file 'src/os_posix.cc'. Vice versa on
non-Windows platforms.

10. Porting hamsterdb Embedded Storage

Porting hamsterdb Embedded Storage shouldn't be too difficult. All operating
system dependend functions are declared in 'src/os.h' and defined
in 'src/os_win32.cc' or 'src/os_posix.cc'.
Other compiler- and OS-specific macros are in 'include/ham/types.h'.
Most likely, these are the only files which have to be touched. Also see item
9) for important macros.

11. Migrating files from older versions

Usually, hamsterdb releases are backwards compatible. There are some exceptions,
though. In this case tools are provided to migrate the database. First, export
your existing database with ham_export linked against the old version.
(ham_export links statically and will NOT be confused if your system has a
newer version of hamsterdb installed). Then use the newest version of
ham_import to import the data into a new database. You can find ham_export
and ham_import in the "tools" subdirectory.

    Example (ham_export of 2.1.2 was renamed to ham_export-2.1.2 to document
        that it's an older version):

    ham_export-2.1.2 input.db | ham_import --stdin output.db

12. Licensing

hamsterdb Embedded Storage can be licensed on a per-developer basis for
closed source applications. For more details, see
http://hamsterdb.com/licensing and http://hamsterdb.com/store.

hamsterdb Embedded Storage is released under GPL2 or later. There are several
exceptions for other open source licenses (see
http://hamsterdb.com/licensing/exceptions for legal information and a license
list).

13. Contact

Author of hamsterdb Embedded Storage is
    Christoph Rupp
    Paul-Preuss-Str. 63
    80995 Muenchen/Germany
    email: chris@crupp.de
    web: http://www.hamsterdb.com

14. Other Copyrights

The Google Protocol Buffers ("protobuf") library is Copyright 2008, Google Inc.
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