Customize

Generally, /var/senna/senna.conf(in Windows, c:\senna\senna.conf) is the setup file for Senna. It has the basic syntax

Parameter Name blank-space Value Line break

You should only modify necessary item. There is no need to change INITIAL_N_SEGMENTS for general usage.

DEFAULT_ENCODING

DEFAULT_ENCODING character code

It sets a character set which is used by Senna. Usable character sets are euc, sjis, or utf8. Default value is euc.

The MeCab's dictionary needs to be set to same character set. (If Senna is bounded to MySQL, the Senna indexed column also needs to be same encoding too.)

MeCab doesn't need if only N-gram is used

If you only use N-gram, you don't need to install MeCab. The following option enables to make MeCab independent Senna.

> ./configure --without-mecab

nfkc.c is a source for doing the normalization of ICU. Currently, it can normalize only for UTF-8.

It makes compiler stressed much, since this source is automatically built by Ruby.

Therefore some environment cannot finish Senna compiling.

If there is no need for normalization of NFKC, you can make NFKC disabled by adding following option:

> ./configure --disable-nfkc

Linux 2.6 or above have a system called AIO/DIO. It enables asynchronous access without using kernel's buffer cache.

By using the system, Kitame (beloged to VA Linux Systems Japan) implemented user level cache for Senna.

Since it use low memory and high-efficiency, it is expected to be a solution for a stage required high performance and severe to use memory resources.

Note to use user level cache

• It is exclusive use for Linux 2.6 or above.
• It is unstable
• In rev. 130, glib 2.8 or above is required.

How to install user level cache

• Add aio option to configure

> ./configure --enable-aio

• Modify environmental variable SEN_AIO_ENABLED as 1 on start up.

Run Senna after set above things.

Some parameters are able to set by modifying directly Senna source code.

Senna itself

Parameter Name	Source Code	Default Value	Detail
SEN_LEX_NGRAM_UNIT_SIZE	senna.h	2	Number of N-gram

MySQL Binding

Parameter Name	Source Code	Default Value	Detail
SENNA_MAX_N_EXPR	myisam/ft_boolean_search.c	32	Max expression set by boolean mode