justpresident / mysql-bit-strings

Mysql UDFs to work with bits in string

mysql-bit-strings

Mysql UDFs to work with bits in string

Provided functions allows you to use strings as long bit arrays. If your application requires to handle more than 64 bits in mysql columns, this library is for you. You can create column up to 255 bytes long as binary(255) and therefore you will have 255*8 available bits to store flags.

Installation

DEB-file

• Install package build dependencies sudo apt-get install devscripts debhelper libmysqlclient-dev g++ gawk

• Build package debuild

• Install package sudo dpkg -i ../mysql-bit-strings-udf_0.01_all.deb

Manual

• Install package build dependencies sudo apt-get install libmysqlclient-dev g++ gawk

• Compile library make

• Install it

sudo cp libmysql_bit_strings_udf.so /usr/lib
sudo cp libmysql_bit_strings_udf.so /usr/lib/mysql/plugin/
mysql < create_funcs.sql

Usage

Suppose you have a table

create table Tbl (
  field1 binary(16);
)

Simple functions

• str_set_bit(STR, BIT_NUM) - allows you to set bit in a string STR at position BIT_NUM

insert into Tbl values
  (str_set_bit("",99));
  
update Tbl set field1 = str_set_bit(field1, 800);

• str_get_bit(STR, BIT_NUM) - returns you a bit from string STR at position BIT_NUM

select str_get_bit(field1, 85) from Tbl

• str_or(STR1, STR2) - returns string with bitwise OR of corresponding bytes in strings STR1 and STR2

select str_or(field1, str_set_bit("",23)) from Tbl

• str_and(STR1, STR2) - returns string with bitwise AND of corresponding bytes in strings STR1 and STR2

Aggregate functions

• str_or_aggr(STR) - bitwise OR of all aggregated fields

select str_or_aggr(field1) from Tbl

• str_and_aggr(STR) - bitwise AND of all aggregated fields

select str_and_aggr(field1) from Tbl