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Compress / Decompress functions based on Unishox for SQLite3

This Sqlite3 loadable extension exposes two functions unishox1c() and unishox1d() to any Sqlite3 database for compressing and decompressing UTF-8 text data.

Preface

Unishox is a compression technique developed for reducing storage size of Short Strings. Details of how it works can be found here.

In general it can achieve upto 65% size reduction for Unicode Short Strings.

Applications

• Compression for low memory devices such as Arduino and ESP8266
• Compression of Chat application text exchange include Emojis
• Storing compressed text in database

This project

This project exposes the compression and decompression functions of Unishox in the form of Sqlite Loadable extension.

The suffix of 1 indicates the version of the compression technique. In case the compression algorithm is changed in future, this implementation will not be affected. That means any text compressed with unishox1c() can be uncompressed only by unishox1d().

Compiling

To compile the loadable extension, use the following commands on unishox1.c downloaded from this repository:

Unix / Linux: gcc -g -fPIC -shared unishox1.c -o unishox1.so

MacOS: gcc -g -fPIC -dynamiclib unishox1.c -o unishox1.dylib

Windows MSVC: cl unishox1.c -link -dll -out:unishox1.dll

Windows MinGW: gcc -g -shared unishox1.c -o unishox1.dll`

Usage

After successful compilation, run sqlite3 from the same folder to open the Sqlite3 console. The following set of commands demonstrate how this extension can be used:

.open test.db
.load unishox1
create table test (lang text, b1 blob);
insert into test values ('English', unishox1c('Beauty is not in the face. Beauty is a light in the heart.'));
insert into test values ('Spanish', unishox1c('La belleza no está en la cara. La belleza es una luz en el corazón.'));
insert into test values ('German', unishox1c('Schönheit findet man nicht im Gesicht. Schönheit strahlt aus dem Herzen.'));
insert into test values ('French', unishox1c('La beauté est pas dans le visage. La beauté est la lumière dans le coeur.'));
insert into test values ('Russian', unishox1c('Красота не в лицо. Красота - это свет в сердце.'));
insert into test values ('Arabic', unishox1c(' الجمال ليس في الوجه. الجمال هو النور الذي في القلب.'));
insert into test values ('Hindi', unishox1c('सुंदरता चेहरे में नहीं है। सौंदर्य हृदय में प्रकाश है।'));
insert into test values ('Chinese', unishox1c('美是不是在脸上。 美是心中的亮光。'));
insert into test values ('Japanese', unishox1c('美は顔にありません。美は心の中の光です。'));
insert into test values ('Emoji', unishox1c('🤣🤣🤣🤣🤣🤣🤣🤣🤣🤣🤣'));
select txt, length(txt) txt_len, clen from (select unishox1d(b1) txt, length(b1) clen from test);

Screenshots

Limitations

• Trying to decompress any blob that was not compressed using unishox1c() will crash the program.
• This works well with short strings as shown above. For longer strings, use compress loadable extension provided in Sqlite website.

Issues

Please contact the author (Arundale Ramanathan) at arun@siara.cc if you find any problem or create issue here.