Reg - full scan limited index

Hi Experts/gurus,
I read Oracle http://docs.oracle.com/cd/B19306_01/server.102/b14211/optimops.htm#i52044 docs, i.e. the difference between the range index scans, full scan and full scan index restricts index. Here is the description of 'Fast Full Index Scans'

Full index scans are an alternative to a full table scan when the index contains all the columns needed for the query, and at least one column in the index key has the NOT NULL constraint. A full scan accesses the data in the index itself, without access to the table. It can be used to eliminate a sort operation, because the data are not classified by the index key. It reads the entire index using multiblock bed, unlike a full index scan and can be parallelized.

Therefore, the document says, the optimizer to choose index FFS, 'at least in the index key column a NOT NULL constraint', but I see less test cases is in complete contrast to what I've read.

I created a table without constraints "NOT NULL".
SQL> create table r_dummy(a number,b varchar2(10));

Table created.

SQL> insert into r_dummy select level,'hi' from dual connect by level<=20;

20 rows created.

SQL> commit;

Commit complete.

SQL> exec dbms_stats.gather_table_stats('HLODS','R_DUMMY');

PL/SQL procedure successfully completed.

SQL> select * from r_dummy where a <= 10;

         A B
---------- ----------
         1 hi
         2 hi
         3 hi
         4 hi
         5 hi
         6 hi
         7 hi
         8 hi
         9 hi
        10 hi

10 rows selected.


Execution Plan
----------------------------------------------------------
Plan hash value: 2533004807

-----------------------------------------------------------------------------
| Id  | Operation         | Name    | Rows  | Bytes | Cost (%CPU)| Time     |
-----------------------------------------------------------------------------
|   0 | SELECT STATEMENT  |         |    10 |    60 |     3   (0)| 00:00:01 |
|*  1 |  TABLE ACCESS FULL| R_DUMMY |    10 |    60 |     3   (0)| 00:00:01 |
-----------------------------------------------------------------------------

Predicate Information (identified by operation id):
---------------------------------------------------

   1 - filter("A"<=10)


Statistics
----------------------------------------------------------
          0  recursive calls
          0  db block gets
          8  consistent gets
          0  physical reads
          0  redo size
        329  bytes sent via SQL*Net to client
        238  bytes received via SQL*Net from client
          2  SQL*Net roundtrips to/from client
          0  sorts (memory)
          0  sorts (disk)
         10  rows processed
As expected under its weight "Full Table Scan", now if I have an index on columns (a, b), if my interpretation is correct, according to the docs, the optimizer should not do a "full Index scan", but Interestingly, it obeys the indication of index_ffs and did a full scan index
SQL> create index r_dummy_idx on r_dummy(a,b);

Index created.

SQL> exec dbms_stats.gather_index_stats('HLODS','R_DUMMY_IDX');

PL/SQL procedure successfully completed.

SQL> select /*+index_ffs(r)*/ * from r_dummy r where a <= 10;

         A B
---------- ----------
         1 hi
         2 hi
         3 hi
         4 hi
         5 hi
         6 hi
         7 hi
         8 hi
         9 hi
        10 hi

10 rows selected.


Execution Plan
----------------------------------------------------------
Plan hash value: 3219236618

------------------------------------------------------------------------------------
| Id  | Operation            | Name        | Rows  | Bytes | Cost (%CPU)| Time     |
------------------------------------------------------------------------------------
|   0 | SELECT STATEMENT     |             |    10 |    60 |     2   (0)| 00:00:01 |
|*  1 |  INDEX FAST FULL SCAN| R_DUMMY_IDX |    10 |    60 |     2   (0)| 00:00:01 |
------------------------------------------------------------------------------------

Predicate Information (identified by operation id):
---------------------------------------------------

   1 - filter("A"<=10)


Statistics
----------------------------------------------------------
          1  recursive calls
          0  db block gets
          4  consistent gets
          0  physical reads
          0  redo size
        330  bytes sent via SQL*Net to client
        238  bytes received via SQL*Net from client
          2  SQL*Net roundtrips to/from client
          0  sorts (memory)
          0  sorts (disk)
         10  rows processed
This clearly shows the optimizer chooses 'INDEX FAST FULL SCAN' even though none of the indexed columns have 'NOT NULL' constraint.

And there is another statement that talks about the results of the COMMAND.

+ "May not be used to eliminate a sort operation, because data are not classified by the index key ' +.

He eliminated the sort operation, I see my results in ascending order.
SQL> drop table r_dummy;

Table dropped.

SQL> create table r_Dummy(a number);

Table created.

SQL> insert into r_dummy values(10);

1 row created.

SQL> insert into r_dummy values(3);

1 row created.

SQL> insert into r_dummy values(1);

1 row created.

SQL> insert into r_dummy values(9);

1 row created.

SQL> insert into r_dummy values(5);

1 row created.

SQL> insert into r_dummy values(4);

1 row created.

SQL> insert into r_dummy values(2);

1 row created.

SQL> insert into r_dummy values(6);

1 row created.

SQL> insert into r_dummy values(7);

1 row created.

SQL> commit;

Commit complete.

SQL> select * from r_dummy;

         A
----------
        10
         3
         1
         9
         5
         4
         2
         6
         7

9 rows selected.

SQL> create index r_dummy_idx on r_dummy(a);

Index created.

SQL> set autotrace on;
SQL> exec dbms_stats.gather_table_stats('HLODS','R_DUMMY');

PL/SQL procedure successfully completed.

SQL> exec dbms_stats.gather_index_stats('HLODS','R_DUMMY_IDX');

PL/SQL procedure successfully completed.
Below you can see the results in ascending order.
SQL> select /*+index_ffs(r)*/ * from r_dummy r where a<=10;

         A
----------
         1
         2
         3
         4
         5
         6
         7
         9
        10

9 rows selected.


Execution Plan
----------------------------------------------------------
Plan hash value: 3219236618

------------------------------------------------------------------------------------
| Id  | Operation            | Name        | Rows  | Bytes | Cost (%CPU)| Time     |
------------------------------------------------------------------------------------
|   0 | SELECT STATEMENT     |             |     9 |    27 |     2   (0)| 00:00:01 |
|*  1 |  INDEX FAST FULL SCAN| R_DUMMY_IDX |     9 |    27 |     2   (0)| 00:00:01 |
------------------------------------------------------------------------------------

Predicate Information (identified by operation id):
---------------------------------------------------

   1 - filter("A"<=10)


Statistics
----------------------------------------------------------
          1  recursive calls
          0  db block gets
          4  consistent gets
          0  physical reads
          0  redo size
        291  bytes sent via SQL*Net to client
        238  bytes received via SQL*Net from client
          2  SQL*Net roundtrips to/from client
          0  sorts (memory)
          0  sorts (disk)
          9  rows processed

SQL>
I am not sure if the docs are wrong or I'm reading wrong. Please help / correct me if my interpretation is poor.

RUSSO says:
Nicosa salvation,
First of all, thank you for your elaborate explanation.

Nicosa wrote:
Will rely on data to order no order by clause and your app will be one day or the other have a bug. + (which, in fact, will not one, as the app has been designed in this way!) +

I don't really do this, I know that even in parallel the same query may return also rows without a prescription. But was surprised to see my results neatly on INDEX NORMAL (non-partitioned). However, I make sure that I have use 'order by' when I want my results to order.

But still I'm not sure, how the absence of constraint column 'NOT NULL' in the index would stop optimizer to do a full scan limited index

Oracle does not index lines where all coluumns in the index are null. So, in your first example it could be possible that there is a line wiith the two a and b null. Oracle could not return this line using an index full assessment because it would not be in the index. However, by adding a predicate on a indexed columns say you actually column is not null.

In the table, that I used in my example above, all three columns are nullable. Take into account:

SQL> select acctno, count(*) from pttrans
  2  group by acctno;

Execution Plan
----------------------------------------------------------
Plan hash value: 3294770776

--------------------------------------------------------------------------------------
| Id  | Operation          | Name    | Rows  | Bytes |TempSpc| Cost (%CPU)| Time     |
--------------------------------------------------------------------------------------
|   0 | SELECT STATEMENT   |         |   532K|  6239K|       | 48143   (2)| 00:09:38 |
|   1 |  HASH GROUP BY     |         |   532K|  6239K|   107M| 48143   (2)| 00:09:38 |
|   2 |   TABLE ACCESS FULL| PTTRANS |  5081K|    58M|       | 37895   (1)| 00:07:35 |
--------------------------------------------------------------------------------------

SQL> select acctno, count(*) from pttrans
  2  where acctno is not null
  3  group by acctno;

Execution Plan
----------------------------------------------------------
Plan hash value: 3737827862

------------------------------------------------------------------------------------------
| Id  | Operation             | Name     | Rows  | Bytes |TempSpc| Cost (%CPU)| Time     |
------------------------------------------------------------------------------------------
|   0 | SELECT STATEMENT      |          |   532K|  6239K|       | 20641   (4)| 00:04:08 |
|   1 |  HASH GROUP BY        |          |   532K|  6239K|   107M| 20641   (4)| 00:04:08 |
|*  2 |   INDEX FAST FULL SCAN| PTTRANS1 |  5081K|    58M|       | 10393   (2)| 00:02:05 |
------------------------------------------------------------------------------------------

Predicate Information (identified by operation id):
---------------------------------------------------

   2 - filter("ACCTNO" IS NOT NULL)

The first query must examine acctno null to get the correct number, but the second, because I asked explicitly not null can use the index.

John

Tags: Database

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BANNER
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Oracle Database 10g Enterprise Edition Release 10.2.0.2.0 - 64bi
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CORE    10.2.0.2.0      Production
TNS for Solaris: Version 10.2.0.2.0 - Production
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----------------------------------------------------------------------------------------------
| Id  | Operation              | Name                | Rows  | Bytes | Cost (%CPU)| Time     |
----------------------------------------------------------------------------------------------
|   0 | SELECT STATEMENT       |                     |     2 |    18 |     2  (50)| 00:00:01 |
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Predicate Information (identified by operation id):
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COLUMN_NAME                    DATA_TYPE                      NUM_DISTINCT  NUM_NULLS    DENSITY HISTOGRAM
------------------------------ ------------------------------ ------------ ---------- ---------- ---------------
CHARGECODEID                   NUMBER                                  241          0 .004149378 NONE
CHARGEID                       NUMBER                                  296          0 .003378378 NONE


INDEX_NAME                     COLUMN_NAME                    COLUMN_POSITION
------------------------------ ------------------------------ ---------------
NBFC_xyz_PK                     CHARGEID                                     1
xyz_IDX1                        CHARGECODEID                                 1
xyz_IDX1                      TXNTYPE                                      2
xyz_IDX1                      MODULEID                                     3
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------------------------------------ ----------- ------------------------------
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optimizer_features_enable            string      10.2.0.2
optimizer_index_caching              integer     0
optimizer_index_cost_adj             integer     100
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----------------------------------------------------------
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    episode.episode_id , episode.cross_ref_id , episode.date_required , 
    product.number_required , 
    request.site_id 
FROM episode 
LEFT JOIN REQUEST on episode.cross_ref_id = request.cross_ref_id 
     JOIN product ON episode.episode_id = product.episode_id 
LEFT JOIN product_sub_type ON product.prod_sub_type_id = product_sub_type.prod_sub_type_id 
WHERE (
        episode.department_id = 2
    and product.status = 'I'
      ) 
ORDER BY episode.date_required
;
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    SQL_ID  5ckbvabcmqzw7, child number 0
-------------------------------------
SELECT     episode.episode_id , episode.cross_ref_id , episode.date_required ,
product.number_required ,     request.site_id FROM episode LEFT JOIN REQUEST on
episode.cross_ref_id = request.cross_ref_id      JOIN product ON episode.episode_id =
product.episode_id LEFT JOIN product_sub_type ON product.prod_sub_type_id =
product_sub_type.prod_sub_type_id WHERE (         episode.department_id = 2 and
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Plan hash value: 3976293091

-----------------------------------------------------------------------------------------------------
| Id  | Operation             | Name                | Rows  | Bytes |TempSpc| Cost (%CPU)| Time     |
-----------------------------------------------------------------------------------------------------
|   0 | SELECT STATEMENT      |                     |       |       |       | 35357 (100)|          |
|   1 |  SORT ORDER BY        |                     | 33333 |  1920K|  2232K| 35357   (1)| 00:07:05 |
|   2 |   NESTED LOOPS OUTER  |                     | 33333 |  1920K|       | 34879   (1)| 00:06:59 |
|*  3 |    HASH JOIN OUTER    |                     | 33333 |  1822K|  1728K| 34878   (1)| 00:06:59 |
|*  4 |     HASH JOIN         |                     | 33333 |  1334K|       |   894   (1)| 00:00:11 |
|*  5 |      TABLE ACCESS FULL| PRODUCT             | 33333 |   423K|       |   103   (1)| 00:00:02 |
|*  6 |      TABLE ACCESS FULL| EPISODE             |   299K|  8198K|       |   788   (1)| 00:00:10 |
|   7 |     TABLE ACCESS FULL | REQUEST             |  3989K|    57M|       | 28772   (1)| 00:05:46 |
|*  8 |    INDEX UNIQUE SCAN  | PK_PRODUCT_SUB_TYPE |     1 |     3 |       |  0   (0)|          |
-----------------------------------------------------------------------------------------------------

Predicate Information (identified by operation id):
---------------------------------------------------
   3 - access("EPISODE"."CROSS_REF_ID"="REQUEST"."CROSS_REF_ID")
   4 - access("EPISODE"."EPISODE_ID"="PRODUCT"."EPISODE_ID")
   5 - filter("PRODUCT"."STATUS"='I')
   6 - filter("EPISODE"."DEPARTMENT_ID"=2)
   8 - access("PRODUCT"."PROD_SUB_TYPE_ID"="PRODUCT_SUB_TYPE"."PROD_SUB_TYPE_ID")
    Updated the Query:
    SELECT 
    episode.episode_id , episode.cross_ref_id , episode.date_required , 
    product.number_required , 
    request.site_id 
FROM episode 
LEFT JOIN REQUEST on episode.cross_ref_id = request.cross_ref_id 
     JOIN product ON episode.episode_id = product.episode_id 
WHERE (
        episode.department_id = 2
    and product.status = 'I'
      ) 
ORDER BY episode.date_required
;
    Execution of display_cursor after the execution plan:
    SQL_ID  gbs74rgupupxz, child number 0
-------------------------------------
SELECT     episode.episode_id , episode.cross_ref_id , episode.date_required ,
product.number_required ,     request.site_id FROM episode LEFT JOIN REQUEST on
episode.cross_ref_id = request.cross_ref_id      JOIN product ON episode.episode_id =
product.episode_id WHERE (         episode.department_id = 2     and product.status =
'I'       ) ORDER BY episode.date_required

Plan hash value: 4250628916

----------------------------------------------------------------------------------------------
| Id  | Operation              | Name        | Rows  | Bytes |TempSpc| Cost (%CPU)| Time     |
----------------------------------------------------------------------------------------------
|   0 | SELECT STATEMENT       |             |       |       |       | 10515 (100)|          |
|   1 |  SORT ORDER BY         |             | 33333 |  1725K|  2112K| 10515   (1)| 00:02:07 |
|*  2 |   HASH JOIN OUTER      |             | 33333 |  1725K|  1632K| 10077   (1)| 00:02:01 |
|*  3 |    HASH JOIN           |             | 33333 |  1236K|       |   894   (1)| 00:00:11 |
|*  4 |     TABLE ACCESS FULL  | PRODUCT     | 33333 |   325K|       |   103   (1)| 00:00:02 |
|*  5 |     TABLE ACCESS FULL  | EPISODE     |   299K|  8198K|       |   788   (1)| 00:00:10 |
|   6 |    INDEX FAST FULL SCAN| IX4_REQUEST |  3989K|    57M|       |  3976   (1)| 00:00:48 |
----------------------------------------------------------------------------------------------

Predicate Information (identified by operation id):
---------------------------------------------------
   2 - access("EPISODE"."CROSS_REF_ID"="REQUEST"."CROSS_REF_ID")
   3 - access("EPISODE"."EPISODE_ID"="PRODUCT"."EPISODE_ID")
   4 - filter("PRODUCT"."STATUS"='I')
   5 - filter("EPISODE"."DEPARTMENT_ID"=2)
    Creating the table and Population:
    1 create tables
    2. load data
    3 create indexes
    4. collection of statistics
    --
-- Main table
--
create table episode (
episode_id number (*,0),
department_id number (*,0),
date_required date,
cross_ref_id varchar2 (11),
padding varchar2 (80),
constraint pk_episode primary key (episode_id)
) ;
--
-- Product tables
--
create table product_type (
prod_type_id number (*,0),
code varchar2 (10),
binary_field number (*,0),
padding varchar2 (80),
constraint pk_product_type primary key (prod_type_id)
) ;
--
create table product_sub_type (
prod_sub_type_id number (*,0),
sub_type_name varchar2 (20),
units varchar2 (20),
padding varchar2 (80),
constraint pk_product_sub_type primary key (prod_sub_type_id)
) ;
--
create table product (
product_id number (*,0),
prod_type_id number (*,0),
prod_sub_type_id number (*,0),
episode_id number (*,0),
status varchar2 (1),
number_required number (*,0),
padding varchar2 (80),
constraint pk_product primary key (product_id),
constraint nn_product_episode check (episode_id is not null) 
) ;
alter table product add constraint fk_product 
foreign key (episode_id) references episode (episode_id) ;
alter table product add constraint fk_product_type 
foreign key (prod_type_id) references product_type (prod_type_id) ;
alter table product add constraint fk_prod_sub_type
foreign key (prod_sub_type_id) references product_sub_type (prod_sub_type_id) ;
--
-- Requests
--
create table request (
request_id number (*,0),
department_id number (*,0),
site_id number (*,0),
cross_ref_id varchar2 (11),
padding varchar2 (80),
padding2 varchar2 (80),
constraint pk_request primary key (request_id),
constraint nn_request_department check (department_id is not null),
constraint nn_request_site_id check (site_id is not null)
) ;
--
-- Activity & Users
--
create table activity (
activity_id number (*,0),
user_id number (*,0),
episode_id number (*,0),
request_id number (*,0), -- always NULL!
padding varchar2 (80),
constraint pk_activity primary key (activity_id)
) ;
alter table activity add constraint fk_activity_episode
foreign key (episode_id) references episode (episode_id) ;
alter table activity add constraint fk_activity_request
foreign key (request_id) references request (request_id) ;
--
create table app_users (
user_id number (*,0),
user_name varchar2 (20),
start_date date,
padding varchar2 (80),
constraint pk_users primary key (user_id)
) ;

prompt Loading episode ...
--
insert into episode
with generator as 
(select rownum r
          from (select rownum r from dual connect by rownum <= 1000) a,
               (select rownum r from dual connect by rownum <= 1000) b,
               (select rownum r from dual connect by rownum <= 1000) c
         where rownum <= 1000000
       ) 
select r, 2,
    sysdate + mod (r, 14),
    to_char (r, '0000000000'),
    'ABCDEFGHIJKLMNOPQRSTUVWXYZ' || to_char (r, '000000')
  from generator g
where g.r <= 300000
/
commit ;
--
prompt Loading product_type ...
--
insert into product_type
with generator as 
(select rownum r
          from (select rownum r from dual connect by rownum <= 1000) a,
               (select rownum r from dual connect by rownum <= 1000) b,
               (select rownum r from dual connect by rownum <= 1000) c
         where rownum <= 1000000
       ) 
select r, 
       to_char (r, '000000000'),
       mod (r, 2),
       'ABCDEFGHIJKLMNOPQRST' || to_char (r, '000000')
  from generator g
where g.r <= 12
/
commit ;
--
prompt Loading product_sub_type ...
--
insert into product_sub_type
with generator as 
(select rownum r
          from (select rownum r from dual connect by rownum <= 1000) a,
               (select rownum r from dual connect by rownum <= 1000) b,
               (select rownum r from dual connect by rownum <= 1000) c
         where rownum <= 1000000
       ) 
select r, 
       to_char (r, '000000'),
       to_char (mod (r, 3), '000000'),
       'ABCDE' || to_char (r, '000000')
  from generator g
where g.r <= 15
/
commit ;
--
prompt Loading product ...
--
-- product_id prod_type_id prod_sub_type_id episode_id padding 
insert into product
with generator as 
(select rownum r
          from (select rownum r from dual connect by rownum <= 1000) a,
               (select rownum r from dual connect by rownum <= 1000) b,
               (select rownum r from dual connect by rownum <= 1000) c
         where rownum <= 1000000
       ) 
select r, mod (r, 12) + 1, mod (r, 15) + 1, mod (r, 300000) + 1,
       decode (mod (r, 3), 0, 'I', 1, 'C', 2, 'X', 'U'),
       dbms_random.value (1, 100), NULL
  from generator g
where g.r <= 100000
/
commit ;
--
prompt Loading request ...
--
-- request_id department_id site_id cross_ref_id varchar2 (11) padding 
insert into request
with generator as 
(select rownum r
          from (select rownum r from dual connect by rownum <= 1000) a,
               (select rownum r from dual connect by rownum <= 1000) b,
               (select rownum r from dual connect by rownum <= 1000) c
         where rownum <= 10000000
       ) 
select r, mod (r, 4) + 1, 1, to_char (r, '0000000000'),
'ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz01234567890123456789' || to_char (r, '000000'),
'ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789012345678' || to_char (r, '000000')
  from generator g
where g.r <= 4000000
/
commit ;
--
prompt Loading activity ...
--
-- activity activity_id user_id episode_id request_id (NULL) padding 
insert into activity
with generator as 
(select rownum r
          from (select rownum r from dual connect by rownum <= 1000) a,
               (select rownum r from dual connect by rownum <= 1000) b,
               (select rownum r from dual connect by rownum <= 1000) c
         where rownum <= 10000000
       ) 
select r, mod (r, 50) + 1, mod (r, 300000) + 1, NULL, NULL
  from generator g
where g.r <= 100000
/
commit ;
--
prompt Loading app_users ...
--
-- app_users user_id user_name start_date padding 
insert into app_users
with generator as 
(select rownum r
          from (select rownum r from dual connect by rownum <= 1000) a,
               (select rownum r from dual connect by rownum <= 1000) b,
               (select rownum r from dual connect by rownum <= 1000) c
         where rownum <= 10000000
       ) 
select r, 
       'User_' || to_char (r, '000000'),
       sysdate - mod (r, 30),
       'ABCDEFGHIJKLMNOPQRSTUVWXYZ' || to_char (r, '000000')
  from generator g
where g.r <= 1000
/
commit ;
--

prompt Episode (1)
create index ix1_episode_cross_ref on episode (cross_ref_id) ;
--
prompt Product (2)
create index ix1_product_episode on product (episode_id) ;
create index ix2_product_type on product (prod_type_id) ;
--
prompt Request (4)
create index ix1_request_site on request (site_id) ;
create index ix2_request_dept on request (department_id) ;
create index ix3_request_cross_ref on request (cross_ref_id) ;
-- The extra index on the referenced columns!!
create index ix4_request on request (cross_ref_id, site_id) ;
--
prompt Activity (2)
create index ix1_activity_episode on activity (episode_id) ;
create index ix2_activity_request on activity (request_id) ;
--
prompt Users (1)
create unique index ix1_users_name on app_users (user_name) ;
--
prompt Gather statistics on schema ...
--
exec dbms_stats.gather_schema_stats ('JB')
    10053 sections - original query
    ***************************************
SINGLE TABLE ACCESS PATH
  -----------------------------------------
  BEGIN Single Table Cardinality Estimation
  -----------------------------------------
  Table: REQUEST  Alias: REQUEST
    Card: Original: 3994236  Rounded: 3994236  Computed: 3994236.00  Non Adjusted: 3994236.00
  -----------------------------------------
  END   Single Table Cardinality Estimation
  -----------------------------------------
  Access Path: TableScan
    Cost:  28806.24  Resp: 28806.24  Degree: 0
      Cost_io: 28738.00  Cost_cpu: 1594402830
      Resp_io: 28738.00  Resp_cpu: 1594402830
******** Begin index join costing ********
  ****** trying bitmap/domain indexes ******
  Access Path: index (FullScan)
    Index: PK_REQUEST
    resc_io: 7865.00  resc_cpu: 855378926
    ix_sel: 1  ix_sel_with_filters: 1
    Cost: 7901.61  Resp: 7901.61  Degree: 0
  Access Path: index (FullScan)
    Index: PK_REQUEST
    resc_io: 7865.00  resc_cpu: 855378926
    ix_sel: 1  ix_sel_with_filters: 1
    Cost: 7901.61  Resp: 7901.61  Degree: 0
  ****** finished trying bitmap/domain indexes ******
******** End index join costing ********
  Best:: AccessPath: TableScan
         Cost: 28806.24  Degree: 1  Resp: 28806.24  Card: 3994236.00  Bytes: 0
***************************************
    10053 - updated the Query
    ***************************************
SINGLE TABLE ACCESS PATH
  -----------------------------------------
  BEGIN Single Table Cardinality Estimation
  -----------------------------------------
  Table: REQUEST  Alias: REQUEST
    Card: Original: 3994236  Rounded: 3994236  Computed: 3994236.00  Non Adjusted: 3994236.00
  -----------------------------------------
  END   Single Table Cardinality Estimation
  -----------------------------------------
  Access Path: TableScan
    Cost:  28806.24  Resp: 28806.24  Degree: 0
      Cost_io: 28738.00  Cost_cpu: 1594402830
      Resp_io: 28738.00  Resp_cpu: 1594402830
  Access Path: index (index (FFS))
    Index: IX4_REQUEST
    resc_io: 3927.00  resc_cpu: 583211030
    ix_sel: 0.0000e+00  ix_sel_with_filters: 1
  Access Path: index (FFS)
    Cost:  3951.96  Resp: 3951.96  Degree: 1
      Cost_io: 3927.00  Cost_cpu: 583211030
      Resp_io: 3927.00  Resp_cpu: 583211030
  Access Path: index (FullScan)
    Index: IX4_REQUEST
    resc_io: 14495.00  resc_cpu: 903225273
    ix_sel: 1  ix_sel_with_filters: 1
    Cost: 14533.66  Resp: 14533.66  Degree: 1
******** Begin index join costing ********
  ****** trying bitmap/domain indexes ******
  Access Path: index (FullScan)
    Index: IX4_REQUEST
    resc_io: 14495.00  resc_cpu: 903225273
    ix_sel: 1  ix_sel_with_filters: 1
    Cost: 14533.66  Resp: 14533.66  Degree: 0
  Access Path: index (FullScan)
    Index: IX4_REQUEST
    resc_io: 14495.00  resc_cpu: 903225273
    ix_sel: 1  ix_sel_with_filters: 1
    Cost: 14533.66  Resp: 14533.66  Degree: 0
  ****** finished trying bitmap/domain indexes ******
******** End index join costing ********
  Best:: AccessPath: IndexFFS  Index: IX4_REQUEST
         Cost: 3951.96  Degree: 1  Resp: 3951.96  Card: 3994236.00  Bytes: 0
***************************************

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