CTX_ANL Package

6 CTX_ANL Package

This chapter contains the following topics.

6.1 About CTX_ANL Package Procedures

The CTX_ANL PL/SQL package is used with AUTO_LEXER and provides procedures for adding and dropping a custom dictionary from the lexer. A custom dictionary might be one that you develop for a special field of study or for your industry. In most cases, the dictionaries supplied with Oracle Text are more than sufficient to handle your requirements.

Name	Description
ADD_DICTIONARY	Adds a custom dictionary to the lexer.
DROP_DICTIONARY	Drops a custom dictionary from the lexer.

6.2 ADD_DICTIONARY

Use the CTX_ANL.ADD_DICTIONARY procedure to add a custom dictionary to be used by "AUTO_LEXER".

Note:

The dictionary data is not processed until index/policy creation time or ALTER INDEX time. Errors in dictionary data format are detected at index/policy creation time or ALTER INDEX time and result in error: DRG-13710: Syntax Error in Dictionary.

Syntax

CTX_ANL.ADD_DICTIONARY(
  name          in VARCHAR2,
  language      in VARCHAR2,
  dictionary    in CLOB
  );

name: The unique name for the user-created custom dictionary.

Note:

The unique name may not be prefixed by the schema or the owner name as this syntax is not supported.
language: The language used by the custom dictionary.
dictionary: The CLOB containing the custom dictionary. The custom dictionary comprises a list of definitions, which are declared separated by a tab or one per line as described in "Custom Dictionary Format and Syntax".

Custom Dictionary Format and Syntax

The custom dictionary enables you to define a new stem or redefine an existing stem to add words to AUTO_LEXER for your language.

Define a new stem or redefine an existing one using the following syntax:

COMPOUND<tab>word|word<tab>STEM<tab>word<tab>parts-of-speech<tab>features

COMPOUND

Use COMPOUND to create a compound word by joining two whole words with a pipe (|). The word is a simple text string that you want to join to another word to create one compound word to add to the language you specify in AUTO_LEXER.

Note that COMPOUND supports a maximum of 8 component words for a compound word.

STEM: Use STEM to add the root for a new word.

word: For COMPOUND and STEM, the word value is a simple text string respresenting a word that you want to join with another word to create a new word; or a word root or stem that you want to add to the language dictionary in AUTO_LEXER.

parts-of-speech: The parts-of-speech value is a list of valid parts of speech, separated by a comma. Table 6-1 lists the names for parts-of-speech value. At least one parts-of-speech value is required.

features: The features represent a list of valid linguistic features, as shown in Table 6-2. Multiple features are separated by a comma. Features are optional. If the word is already defined in the supplied language dictionary, then this definition overrides it. It is an error to have an invalid value for parts-of-speech or features.

Table 6-1 Custom Dictionary Valid Parts-of-Speech (case sensitive)

Part-of-Speech	Description
noun	A simple noun, like table, book, or procedure.
nounProper	A proper name, for person, place, etc., typically capitalized, like Zachary, Supidito, Susquehanna
adjective	Modifiers of nouns, which typically can be compared (green, greener, greenest), like fast, trenchant, pendulous.
adverb	Any general modifier of a sentence that may modify an adjective or verb or may stand alone, like slowly, yet, perhaps.
preposition	A word that forms a prepositional phrase with a noun, like off, beside, from. Used for postpositions too, in languages that have postpositions of similar function.

Table 6-2 lists the features and their usage. The specified language determines whether these are relevant and necessary. Note that declension refers to the inflection some languages use to determine number (singular or plural), case, and gender. The features are relevant depending on the language for the custom dictionary.

Table 6-2 Custom Dictionary Valid Features

Feature (case sensitive)	Description
genderMasculine	masculine
genderFeminine	feminine
genderNeuter	neuter
declensionHard	hard declension
declensionSoft	soft declension

Examples

exec CTX_DDL.CREATE_PREFERENCE('A_LEX', 'AUTO_LEXER');
exec CTX_ANL. ADD_DICTIONARY('my_dict1', 'ENGLISH', lobloc);
select * from CTX_USR_ANL_DICTS;
exec CTX_DDL.SET_ATTRIBUTE('A_LEX', 'english_dictionary', 'MY_ENGLISH');

The following example creates a custom dictionary named d1 to be added to AUTO_LEXER for the English language.

declare
 dict clob;
begin
 dict := '# compounds
COMPOUND        help|desk
COMPOUND        help|desks
COMPOUND        book|shelf
COMPOUND        book|shelves
COMPOUND        back|woods|man
'||
'# define company abbreviations
STEM    comp.   noun
STEM    ltd.    noun
STEM    co.     noun
STEM    oracle  nounProper
STEM    make    verb
STEM    unkword noun
STEM    unkword verb
';
 ctx_anl.add_dictionary('d1','ENGLISH',dict);
end;
/

6.3 DROP_DICTIONARY

Use this procedure to drop a custom dictionary from AUTO_LEXER.

Syntax

CTX_ANL.DROP_DICTIONARY(
  name          in VARCHAR2,
  language      in VARCHAR2,
  dictionary    in CLOB
  );

name: The unique name for the user-created custom dictionary.

Note:

The unique name may not be prefixed by the schema or the owner name as this syntax is not supported.
language: The language for the custom dictionary.
dictionary: The CLOB representing the custom dictionary.

Example

begin
   CTX_ANL.DROP_DICTIONARY('dict1', 'english', 'dictionary');
end;