Query using progressive relaxation take more time for execution

Question

HI Gurus,
I am creating a query using context index and progressive relaxation
I had started using progressive relaxation after getting inputs from forum {thread:id=2333942} . Using progressive relaxation takes more than 7 seconds for every query. Is there any way we can improve the performance of the query?
create table test_sh4 (text1 clob,text2 clob,text3 clob);
begin
   ctx_ddl.create_preference ('nd_mcd', 'multi_column_datastore');
   ctx_ddl.set_attribute
      ('nd_mcd',
       'columns',
       'replace (text1, '' '', '''') nd1,
        text1 text1,
        replace (text2, '' '', '''') nd2,
        text2 text2');
   ctx_ddl.create_preference ('test_lex1', 'basic_lexer');
   ctx_ddl.set_attribute ('test_lex1', 'whitespace', '/\|-_+');
   ctx_ddl.create_section_group ('test_sg', 'basic_section_group');
   ctx_ddl.add_field_section ('test_sg', 'text1', 'text1', true);
   ctx_ddl.add_field_section ('test_sg', 'nd1', 'nd1', true);
   ctx_ddl.add_field_section ('test_sg', 'text2', 'text2', true);
   ctx_ddl.add_field_section ('test_sg', 'nd2', 'nd2', true);
end;
create index IX_test_sh4 on test_sh4 (text3)   indextype is ctxsys.context   parameters    ('datastore     nd_mcd   lexer test_lex1 section group     test_sg') ;
alter index IX_test_sh4 REBUILD PARAMETERS ('REPLACE SYNC (ON COMMIT)') ;-- sync index on every commit.
SELECT SCORE(1) score,t.* FROM test_sh4 t WHERE CONTAINS (text3,  '
<query>
<textquery>
<progression>
<seq>{GIFT GRILL STAPLES CARD} within text1</seq>
<seq>{GIFTGRILLSTAPLESCARD} within nd1</seq>
<seq>{GIFT GRILL STAPLES CARD} within text2</seq>
<seq>{GIFTGRILLSTAPLESCARD} within nd2</seq>
<seq>((%GIFT% and %GRILL% and %STAPLES% and %CARD%)) within text1</seq>
<seq>((%GIFT% and %GRILL% and %STAPLES% and %CARD%)) within text2</seq>
<seq>((%GIFT% and %GRILL% and %STAPLES%) or (%GRILL% and %STAPLES% and %CARD%) or (%GIFT% and %STAPLES% and %CARD%) or (%GIFT% and %GRILL% and %CARD%)) within text1</seq>
<seq>((%GIFT% and %GRILL% and %STAPLES%) or (%GRILL% and %STAPLES% and %CARD%) or (%GIFT% and %STAPLES% and %CARD%) or (%GIFT% and %GRILL% and %CARD%)) within text2</seq>
<seq>((%STAPLES% and %CARD%) or (%GIFT% and %GRILL%) or (%GRILL% and %CARD%) or (%GIFT% and %CARD%) or (%GIFT% and %STAPLES%) or (%GRILL% and %STAPLES%)) within text1</seq>
<seq>((%STAPLES% and %CARD%) or (%GIFT% and %GRILL%) or (%GRILL% and %CARD%) or (%GIFT% and %CARD%) or (%GIFT% and %STAPLES%) or (%GRILL% and %STAPLES%)) within text2</seq>
<seq>((%GIFT% , %GRILL% , %STAPLES% , %CARD%)) within text1</seq>
<seq>((%GIFT% , %GRILL% , %STAPLES% , %CARD%)) within text2</seq>
<seq>((!GIFT and !GRILL and !STAPLES and !CARD)) within text1</seq>
<seq>((!GIFT and !GRILL and !STAPLES and !CARD)) within text2</seq>
<seq>((!GIFT and !GRILL and !STAPLES) or (!GRILL and !STAPLES and !CARD) or (!GIFT and !STAPLES and !CARD) or (!GIFT and !GRILL and !CARD)) within text1</seq>
<seq>((!GIFT and !GRILL and !STAPLES) or (!GRILL and !STAPLES and !CARD) or (!GIFT and !STAPLES and !CARD) or (!GIFT and !GRILL and !CARD)) within text2</seq>
<seq>((!STAPLES and !CARD) or (!GIFT and !GRILL) or (!GRILL and !CARD) or (!GIFT and !CARD) or (!GIFT and !STAPLES) or (!GRILL and !STAPLES)) within text1</seq>
<seq>((!STAPLES and !CARD) or (!GIFT and !GRILL) or (!GRILL and !CARD) or (!GIFT and !CARD) or (!GIFT and !STAPLES) or (!GRILL and !STAPLES)) within text2</seq>
<seq>((!GIFT , !GRILL , !STAPLES , !CARD)) within text1</seq>
<seq>((!GIFT , !GRILL , !STAPLES , !CARD)) within text2</seq>
<seq>((?GIFT and ?GRILL and ?STAPLES and ?CARD)) within text1</seq>
<seq>((?GIFT and ?GRILL and ?STAPLES and ?CARD)) within text2</seq>
<seq>((?GIFT and ?GRILL and ?STAPLES) or (?GRILL and ?STAPLES and ?CARD) or (?GIFT and ?STAPLES and ?CARD) or (?GIFT and ?GRILL and ?CARD)) within text1</seq>
<seq>((?GIFT and ?GRILL and ?STAPLES) or (?GRILL and ?STAPLES and ?CARD) or (?GIFT and ?STAPLES and ?CARD) or (?GIFT and ?GRILL and ?CARD)) within text2</seq>
<seq>((?STAPLES and ?CARD) or (?GIFT and ?GRILL) or (?GRILL and ?CARD) or (?GIFT and ?CARD) or (?GIFT and ?STAPLES) or (?GRILL and ?STAPLES)) within text1</seq>
<seq>((?STAPLES and ?CARD) or (?GIFT and ?GRILL) or (?GRILL and ?CARD) or (?GIFT and ?CARD) or (?GIFT and ?STAPLES) or (?GRILL and ?STAPLES)) within text2</seq>
<seq>((?GIFT , ?GRILL , ?STAPLES , ?CARD)) within text1</seq>
<seq>((?GIFT , ?GRILL , ?STAPLES , ?CARD)) within text2</seq>
</progression>
</textquery>
<score datatype="FLOAT" algorithm="default"/>
</query>',1) >0 ORDER BY score(1) DESC

Answer 1

Progressive relaxation works best when you're only selecting a limited number of rows. If you fetch ALL the rows which satisfy the query, then all the steps in the relaxation will have to run regardless.
If you fetch - say - the first 10 results, then if the first step of the relaxation provides 10 results then there is no need to execute the next step (in fact, due to internal buffering, that won't be exactly true but it's conceptually correct).
The simplest way to do this is reword the query as
SELECT * FROM (
( SELECT SCORE(1) score,t.* FROM test_sh4 t WHERE CONTAINS (text3, '
<query>
<textquery>
</textquery>
<score datatype="FLOAT" algorithm="default"/>
</query>',1) >0 ORDER BY score(1) DESC
WHERE ROWNUM <= 10
You've discovered that leading wild cards don't work too well unless you use SUBSTRING_INDEX. I would encourage you to avoid them altogether if possible, or push them down much lower in the progressive relaxation. Usually, GIFT% is a useful expression (matches GIFTS, GIFTED, etc), %GIFT% is generally no more effective.
There are a lot of steps in your progressive relaxation. It you wanted to reduce the number of steps, you could change:
<seq>((%GIFT% and %GRILL% and %STAPLES% and %CARD%)) within text1</seq>
<seq>((%GIFT% and %GRILL% and %STAPLES% and %CARD%)) within text2</seq>
to
<seq>((%GIFT% and %GRILL% and %STAPLES% and %CARD%)*2) within text1 ACCUM ((%GIFT% and %GRILL% and %STAPLES% and %CARD%)) within text2</seq>
I don't know if this would have any performance benefits - but it's worth trying it to see.