Word forms

Word forms are applied after tokenizing incoming text by charset_table rules. They essentially let you replace one word with another. Normally, that would be used to bring different word forms to a single normal form (e.g. to normalize all the variants such as “walks”, “walked”, “walking” to the normal form “walk”). It can also be used to implement stemming exceptions, because stemming is not applied to words found in the forms list.

wordforms

wordforms = path/to/wordforms.txt
wordforms = path/to/alternateforms.txt
wordforms = path/to/dict*.txt

Word forms dictionary. Optional, default is empty.

The dictionaries are used to normalize incoming words both during indexing and searching. Therefore, when it comes to a plain table, it’s required to rotate the table in order to pick up changes in the word forms file.

Word forms support in Manticore is designed to handle large dictionaries well. They moderately affect indexing speed; for example, a dictionary with 1 million entries slows down indexing by about 1.5 times. Searching speed is not affected at all. The additional RAM impact is roughly equal to the dictionary file size, and dictionaries are shared across tables. For instance, if the very same 50 MB word forms file is specified for 10 different tables, the additional searchd RAM usage will be about 50 MB.

The dictionary file should be in a simple plain text format. Each line should contain source and destination word forms, in UTF-8 encoding, separated by a “greater than” sign. Rules from the charset_table will be applied when the file is loaded, so if you are using built-in charset_table options, it is typically case-insensitive, just like your other full-text indexed data. Here is a sample file contents:

walks > walk
walked > walk
walking > walk

There is a bundled utility called Spelldump that helps you create a dictionary file in a format that Manticore can read. The utility can read from source .dict and .aff dictionary files in the ispell or MySpell format, as bundled with OpenOffice.

You can map several source words to a single destination word. The process happens on tokens, not the source text, so differences in whitespace and markup are ignored.

You can use the => symbol instead of >. Comments (starting with #) are also allowed. Finally, if a line starts with a tilde (~), the wordform will be applied after morphology, instead of before (note that only a single source word is supported in this case).

core 2 duo > c2d
e6600 > c2d
core 2duo => c2d # Some people write '2duo' together...
~run > walk # Along with stem_en morphology enabled replaces 'run', 'running', 'runs' (and any other words that stem to just 'run') to 'walk'

You can specify multiple destination tokens:

s02e02 > season 2 episode 2
s3 e3 > season 3 episode 3

You can specify multiple files, not just one. Masks can be used as a pattern, and all matching files will be processed in simple ascending order.

In the RT mode, only absolute paths are allowed.

If multi-byte codepages are used and file names include foreign characters, the resulting order may not be exactly alphabetic. If the same wordform definition is found in multiple files, the latter one is used and overrides previous definitions.

SQL:

CREATE TABLE products(title text, price float) wordforms = '/var/lib/manticore/wordforms.txt' wordforms = '/var/lib/manticore/alternateforms.txt /var/lib/manticore/dict*.txt'

POST /cli -d "
CREATE TABLE products(title text, price float) wordforms = '/var/lib/manticore/wordforms.txt' wordforms = '/var/lib/manticore/alternateforms.txt' wordforms = '/var/lib/manticore/dict*.txt'"

$index = new \Manticoresearch\Index($client);
$index->setName('products');
$index->create([
            'title'=>['type'=>'text'],
            'price'=>['type'=>'float']
        ],[
            'wordforms' => [
                '/var/lib/manticore/wordforms.txt',
                '/var/lib/manticore/alternateforms.txt',
                '/var/lib/manticore/dict*.txt'
            ]
        ]);

Python:

utilsApi.sql('CREATE TABLE products(title text, price float) wordforms = \'/var/lib/manticore/wordforms.txt\' wordforms = \'/var/lib/manticore/alternateforms.txt\' wordforms = \'/var/lib/manticore/dict*.txt\'')

javascript:

res = await utilsApi.sql('CREATE TABLE products(title text, price float)wordforms = \'/var/lib/manticore/wordforms.txt\' wordforms = \'/var/lib/manticore/alternateforms.txt\' wordforms = \'/var/lib/manticore/dict*.txt\'');

Java:

utilsApi.sql("CREATE TABLE products(title text, price float) wordforms = '/var/lib/manticore/wordforms.txt' wordforms = '/var/lib/manticore/alternateforms.txt' wordforms = '/var/lib/manticore/dict*.txt'");

table products {
  wordforms = /var/lib/manticore/wordforms.txt
  wordforms = /var/lib/manticore/alternateforms.txt
  wordforms = /var/lib/manticore/dict*.txt

  type = rt
  path = tbl
  rt_field = title
  rt_attr_uint = price
}