Product Search Using Oracle Text or By Any Other Methods using PL/SQL

Question

Hi All,
I have requirement for product search using the product table which has around 5 million products. I Need to show top 100 disitnct products searched  in the following order
1. = ProductDescription
2. ProductDescription_%
3. %_ProductDescription_%
4. %_ProductDescription
5. ProductDescription%
6. %ProductDescription
Where '_' is space.  If first two/three/or any criteria itslef gives me 100 records then i need not search for another patterns
Table Structure Is as follows
Create Table Tbl_Product_Lookup
    Barcode_number                Varchar2(9),
    Product_Description Varchar2(200),
    Product_Start_Date Date,
    Product_End_Date Date,
    Product_Price Number(12,4)
Could you please help me implementing this one ? SLA for the search result is 2 seconds
Thanks,
Varun

Answer 1

You could use an Oracle Text context index with a wordlist to speed up substring searches and return all rows that match any of your criteria, combined with a case statement to provide a ranking that can be ordered by within an inner query, then use rownum to limit the rows in an outer query.  You could also use the first_rows(n) hint to speed up the return of limited rows.  Please see the demonstration below.  If you decide to use Oracle Text, you may want to ask further questions in the Oracle Text sub-forum on this forum or space or whatever they call it now.
SCOTT@orcl_11gR2> -- table:
SCOTT@orcl_11gR2> Create Table Tbl_Product_Lookup
  2    (
  3       Barcode_number       Varchar2(9),
  4       Product_Description  Varchar2(200),
  5       Product_Start_Date   Date,
  6       Product_End_Date     Date,
  7       Product_Price          Number(12,4)
  8    )
  9  /
Table created.
SCOTT@orcl_11gR2> -- sample data:
SCOTT@orcl_11gR2> insert all
  2  into tbl_product_lookup (product_description) values ('test product')
  3  into tbl_product_lookup (product_description) values ('test product and more')
  4  into tbl_product_lookup (product_description) values ('another test product and more')
  5  into tbl_product_lookup (product_description) values ('another test product')
  6  into tbl_product_lookup (product_description) values ('test products')
  7  into tbl_product_lookup (product_description) values ('selftest product')
  8  select * from dual
  9  /
6 rows created.
SCOTT@orcl_11gR2> insert into tbl_product_lookup (product_description) select object_name from all_objects
  2  /
75046 rows created.
SCOTT@orcl_11gR2> -- wordlist:
SCOTT@orcl_11gR2> begin
  2    ctx_ddl.create_preference('mywordlist', 'BASIC_WORDLIST');
  3    ctx_ddl.set_attribute('mywordlist','PREFIX_INDEX','TRUE');
  4    ctx_ddl.set_attribute('mywordlist','PREFIX_MIN_LENGTH', '3');
  5    ctx_ddl.set_attribute('mywordlist','PREFIX_MAX_LENGTH', '4');
  6    ctx_ddl.set_attribute('mywordlist','SUBSTRING_INDEX', 'YES');
  7    ctx_ddl.set_attribute('mywordlist', 'wildcard_maxterms', 0) ;
  8  end;
  9  /
PL/SQL procedure successfully completed.
SCOTT@orcl_11gR2> -- context index that uses wordlist:
SCOTT@orcl_11gR2> create index prod_desc_text_idx
  2  on tbl_product_lookup (product_description)
  3  indextype is ctxsys.context
  4  parameters ('wordlist mywordlist')
  5  /
Index created.
SCOTT@orcl_11gR2> -- gather statistics:
SCOTT@orcl_11gR2> exec dbms_stats.gather_table_stats (user, 'TBL_PRODUCT_LOOKUP')
PL/SQL procedure successfully completed.
SCOTT@orcl_11gR2> -- query:
SCOTT@orcl_11gR2> variable productdescription varchar2(100)
SCOTT@orcl_11gR2> exec :productdescription := 'test product'
PL/SQL procedure successfully completed.
SCOTT@orcl_11gR2> column product_description format a45
SCOTT@orcl_11gR2> set autotrace on explain
SCOTT@orcl_11gR2> set timing on
SCOTT@orcl_11gR2> select /*+ FIRST_ROWS(100) */ *
  2  from   (select /*+ FIRST_ROWS(100) */ distinct
  3              case when product_description = :productdescription            then 1
  4               when product_description like :productdescription || ' %'       then 2
  5               when product_description like '% ' || :productdescription || ' %' then 3
  6               when product_description like '% ' || :productdescription       then 4
  7               when product_description like :productdescription || '%'       then 5
  8               when product_description like '%' || :productdescription       then 6
  9              end as ranking,
10              product_description
11           from   tbl_product_lookup
12           where  contains (product_description, '%' || :productdescription || '%') > 0
13           order  by ranking)
14  where  rownum <= 100
15  /
   RANKING PRODUCT_DESCRIPTION
         1 test product
         2 test product and more
         3 another test product and more
         4 another test product
         5 test products
         6 selftest product
6 rows selected.
Elapsed: 00:00:00.10
Execution Plan
Plan hash value: 459057338
| Id  | Operation                      | Name               | Rows  | Bytes | Cost (%CPU)| Time     |
|   0 | SELECT STATEMENT               |                    |    38 |  3990 |    13  (16)| 00:00:01 |
|*  1 |  COUNT STOPKEY                 |                    |       |       |            |          |
|   2 |   VIEW                         |                    |    38 |  3990 |    13  (16)| 00:00:01 |
|*  3 |    SORT UNIQUE STOPKEY         |                    |    38 |   988 |    12   (9)| 00:00:01 |
|   4 |     TABLE ACCESS BY INDEX ROWID| TBL_PRODUCT_LOOKUP |    38 |   988 |    11   (0)| 00:00:01 |
|*  5 |      DOMAIN INDEX              | PROD_DESC_TEXT_IDX |       |       |     4   (0)| 00:00:01 |
Predicate Information (identified by operation id):
   1 - filter(ROWNUM<=100)
   3 - filter(ROWNUM<=100)
   5 - access("CTXSYS"."CONTAINS"("PRODUCT_DESCRIPTION",'%'||:PRODUCTDESCRIPTION||'%')>0)
SCOTT@orcl_11gR2>