CREATE TABLE ott
(
 id      NUMBER(2) NOT NULL,
 texts   VARCHAR2(2000 CHAR),
 CONSTRAINT ott_pk PRIMARY KEY(id)
);

INSERT INTO ott(id, texts)
      VALUES (
              1,
              'Пробовал сделать полнотекстовый поиск при помощи Oracle Text. Все сделал как в http://oraclestart.blogspot.in/2013/08/oracle-text.html
создание индекса прошло без ошибок.

Запрос select * from docs where contains(text, ''саша'') > 0; возвращает нужную строку, а вот

select * from docs where contains(text, ''$идти'') > 0; ничего не возвращает.

Если просмотреть служебную таблицу DR$DOCS_IDX$I, то в TOKEN_TEXT есть значение "ИДТИ"

В чем может быть причина? );');

INSERT INTO ott(id, texts)
      VALUES (
              2,
              'Может Вы что то недопоняли, может я

https://docs.oracle.com/database/121/CCREF/amultlng.htm#CCREF1350

D.2.3.5 Index stems
This feature enables you to specify a stemmer for stem indexing. Tokens are stemmed to a single base form at index time in addition to the normal forms. Specifying index stems enables better query performance for stem queries, for example $computed.

This feature is supported for English, Dutch, French, German, Italian, and Spanish.

Но даже в этом случае слово "идти" может быть написано в тексте как "шел" "идти" "ходил" ... В начале предложения с первой большой буквы. Если слово ВСЕ большими буквами, я думаю, его воспримут как имя собственное и в поиске оно участвовать не будет. Но это мои догадки. Можно еще почитать про About');

/*==============================================================*/
/* Index: Oracle Text                                           */
/*==============================================================*/
CREATE INDEX idx_oratxt_texts
 ON ott(texts)
 INDEXTYPE IS ctxsys.context
  PARAMETERS('STOPLIST CTXSYS.EMPTY_STOPLIST SYNC (ON COMMIT)');

BEGIN
 DBMS_STATS.gather_table_stats(ownname => USER, tabname => 'OTT', estimate_percent => 100, cascade => TRUE);
 DBMS_STATS.gather_index_stats(ownname => USER, indname => 'IDX_ORATXT_TEXTS', estimate_percent => 100);
END;
/

SELECT id  FROM ott WHERE contains(texts, 'саша') > 0;
        ID
----------
         1
1 row selected.

SELECT id  FROM ott WHERE contains(texts, 'САША') > 0;
        ID
----------
         1
1 row selected.


SELECT id  FROM ott WHERE contains(texts, 'Саша') > 0;
        ID
----------
         1
1 row selected.

SELECT id  FROM ott WHERE contains(texts, '$шла') > 0;
no rows selected.

SELECT id  FROM ott WHERE contains(texts, 'А AND сАША AND Может AND иДТИ AND  и% AND без AND ИНДЕКСА') > 0;
        ID
----------
         1
1 row selected.

SELECT id  FROM ott WHERE contains(texts, 'French AND German AND что то недопоняли') > 0;
        ID
----------
         2
1 row selected.

select * from v$version;

BANNER                                                                          
--------------------------------------------------------------------------------
Oracle Database 11g Enterprise Edition Release 11.2.0.4.0 - 64bit Production    
PL/SQL Release 11.2.0.4.0 - Production                                          
CORE	11.2.0.4.0	Production                                                      
TNS for Linux: Version 11.2.0.4.0 - Production                                  
NLSRTL Version 11.2.0.4.0 - Production                                          

5 rows selected.

create table docs (id number not null, text varchar2(1000 char) not null);
insert into docs values (1, 'Шла Саша по шоссе и сосала сушку.');
insert into docs values (2, 'London is the capital of The United Kingdom of Great Britain and Northern Ireland.');
begin
    ctx_ddl.create_preference('my_wordlist', 'BASIC_WORDLIST');
    ctx_ddl.create_preference('my_lexer', 'AUTO_LEXER');
    ctx_ddl.set_attribute('my_lexer', 'INDEX_STEMS','YES');
end;
create index docs_idx on docs (text) indextype is ctxsys.context parameters ('LEXER my_lexer WORDLIST my_wordlist');

Table created.
1 row created.
1 row created.
PL/SQL procedure successfully completed.
create index docs_idx on docs (text) indextype is ctxsys.context parameters ('LEXER my_lexer WORDLIST my_wordlist')
Error at line 9
ORA-29855: error occurred in the execution of ODCIINDEXCREATE routine
ORA-20000: Oracle Text error:
DRG-10502: index DOCS_IDX does not exist
DRG-11135: feature not generally available

ORA-06512: at "CTXSYS.DRUE", line 160
ORA-06512: at "CTXSYS.TEXTINDEXMETHODS", line 366

select banner from v$version;

BANNER                                                                          
--------------------------------------------------------------------------------
Oracle Database 12c Enterprise Edition Release 12.1.0.2.0 - 64bit Production    
PL/SQL Release 12.1.0.2.0 - Production                                          
CORE	12.1.0.2.0	Production                                                      
TNS for Linux: Version 12.1.0.2.0 - Production                                  
NLSRTL Version 12.1.0.2.0 - Production                                          

5 rows selected.

create table docs (id number not null, text varchar2(1000 char) not null);
insert into docs values (1, 'Шла Саша по шоссе и сосала сушку.');
insert into docs values (2, 'London is the capital of The United Kingdom of Great Britain and Northern Ireland.');
begin
    ctx_ddl.create_preference('my_wordlist', 'BASIC_WORDLIST');
    ctx_ddl.create_preference('my_lexer', 'AUTO_LEXER');
    ctx_ddl.set_attribute('my_lexer', 'INDEX_STEMS','YES');
end;
create index docs_idx on docs (text) indextype is ctxsys.context parameters ('LEXER my_lexer WORDLIST my_wordlist');

Table created.
1 row created.
1 row created.
PL/SQL procedure successfully completed.
Index created.

select id from docs where contains(text, 'саша') > 0;

        ID
----------
         1
1 row selected.

select id from docs where contains(text, '$идти') > 0;

        ID
----------
         1
1 row selected.

select id from docs where contains(text, 'united') > 0;

        ID
----------
         2
1 row selected.

select id from docs where contains(text, 'uni%') > 0;

        ID
----------
         2
1 row selected.

select banner from v$version;

BANNER                                                                          
--------------------------------------------------------------------------------
Oracle Database 12c Enterprise Edition Release 12.1.0.2.0 - 64bit Production    
PL/SQL Release 12.1.0.2.0 - Production                                          
CORE	12.1.0.2.0	Production                                                      
TNS for Linux: Version 12.1.0.2.0 - Production                                  
NLSRTL Version 12.1.0.2.0 - Production                                          

5 rows selected.

create table docs (id number not null, text varchar2(1000 char) not null);
insert into docs values (1, 'Шла Саша по шоссе и сосала сушку.');
insert into docs values (2, 'London is the capital of The United Kingdom of Great Britain and Northern Ireland.');
begin
    ctx_ddl.create_preference('my_wordlist', 'BASIC_WORDLIST');
    ctx_ddl.create_preference('my_lexer', 'AUTO_LEXER');
    ctx_ddl.set_attribute('my_lexer', 'INDEX_STEMS','YES');
end;
create index docs_idx on docs (text) indextype is ctxsys.context parameters ('LEXER my_lexer WORDLIST my_wordlist');

Table created.
1 row created.
1 row created.
PL/SQL procedure successfully completed.
Index created.

[SRC PLSQL]
select id from docs where contains(text, 'саша') > 0;

        ID
----------
         1
1 row selected.

select id from docs where contains(text, '$идти') > 0;

        ID
----------
         1
1 row selected.

select id from docs where contains(text, 'united') > 0;

        ID
----------
         2
1 row selected.

select id from docs where contains(text, 'uni%') > 0;

        ID
----------
         2
1 row selected.