Function Based Index
Hi All,
select * from v$version;
BANNER
Oracle Database 11g Enterprise Edition Release 11.1.0.7.0 - 64bit Production
PL/SQL Release 11.1.0.7.0 - Production
CORE 11.1.0.7.0 Production
TNS for Linux: Version 11.1.0.7.0 - Production
NLSRTL Version 11.1.0.7.0 - ProductionI have a 10GB partitioned table which has INVOICE_DUE_DATE column. Table is partitioned on CREATION_DATE. All records which has CREATION_DATE less than 01-jan-2010 have INVOICE_DUE_DATE set to NULL and new records (for year 2011)are updated with recent date(i.e. sysdate) by 'due_date_update' process. Some developers want indexing on INVOICE_DUE_DATE column as they have SLA critical reports running against INVOICE_DUE_DATE column. (where INVOICE_DUE_DATE > :B1) B1 could be any date in 2011.
As of now, ~85% records are having INVOICE_DUE_DATE set to NULL.
Given above scenarios,Can i use function based index to index all rows where INVOICE_DUE_DATE is any date in 2011 ?
Edited by: OraDBA02 on Jan 11, 2011 4:00 AM
OraDBA02 wrote:
Given above scenarios,Can i use function based index to index all rows where INVOICE_DUE_DATE is any date in 2011 ?I suppose you could, but you might not need to. If you had an index that just contained the INVOICE_DUE_DATE column it wouldn't index the NULL values anyways.
Similar Messages
-
Function-based index with OR in the wher-clause
We have some problems with functin-based indexes and
the or-condition in a where-clause.
--We use Oracle 8i (8.1.7)
create table TPERSON(ID number(10),NAME varchar2(20),...);
create index I_NORMAL_TPERSON_NAME on TPERSON(NAME);
create index I_FUNCTION_TPERSON_NAME on TPERSON(UPPER(NAME));
The following two statements run very fast on a large table
and the execution-plan asure the usage of the indexes
(-while the session is appropriate configured and the table is analyzed):
1) select count(ID) FROM TPERSON where upper(NAME) like 'MIL%';
2) select count(ID) from TPERSON where NAME like 'Mil%' or (3=5);
In particular we see that a normal index is used while the where-clause contains
an OR-CONDITION.
But if we try the similarly select-statement
3) select count(ID) FROM TPERSON where upper(NAME) like 'MIL%' or (3=5);
the CBO will not use the function-index I_FUNCTION_TPERSON_NAME and we have a full table scan in the execution-plan.
(This behavior we only expect with views but not with indexes.)
We ask for an advice like a hint, which enable the CBO-usage
of function-based indexes in connection with OR.
This problem seems to be artificial because it contains this dummy logic:
or (3=5).
This steams from an prepared statement, where this kind of boolean
flag reduce the amount of different select-statements needed for
covering the hole business-logic, while using bind-variables for the
concrete query-parameters.
A more realistic (still boild down) version of our select-statement is:
select * FROM TPERSON
where (upper(NAME) like 'MIL%' or (NAME is null))
and (upper(FIRSTNAME) like 'MICH% or (FIRSTNAME is null))
and ...;
thank you for time..
email: [email protected]In the realistic statement you write :
select * FROM TPERSON
where (upper(NAME) like 'MIL%' or (NAME is null))
and (upper(FIRSTNAME) like 'MICH% or (FIRSTNAME is null))
and ...;
as far as i know, NULL values are not indexed, "or (NAME is NULL)" have to generate a full table scan.
HTH
We have some problems with functin-based indexes and
the or-condition in a where-clause.
--We use Oracle 8i (8.1.7)
create table TPERSON(ID number(10),NAME varchar2(20),...);
create index I_NORMAL_TPERSON_NAME on TPERSON(NAME);
create index I_FUNCTION_TPERSON_NAME on TPERSON(UPPER(NAME));
The following two statements run very fast on a large table
and the execution-plan asure the usage of the indexes
(-while the session is appropriate configured and the table is analyzed):
1) select count(ID) FROM TPERSON where upper(NAME) like 'MIL%';
2) select count(ID) from TPERSON where NAME like 'Mil%' or (3=5);
In particular we see that a normal index is used while the where-clause contains
an OR-CONDITION.
But if we try the similarly select-statement
3) select count(ID) FROM TPERSON where upper(NAME) like 'MIL%' or (3=5);
the CBO will not use the function-index I_FUNCTION_TPERSON_NAME and we have a full table scan in the execution-plan.
(This behavior we only expect with views but not with indexes.)
We ask for an advice like a hint, which enable the CBO-usage
of function-based indexes in connection with OR.
This problem seems to be artificial because it contains this dummy logic:
or (3=5).
This steams from an prepared statement, where this kind of boolean
flag reduce the amount of different select-statements needed for
covering the hole business-logic, while using bind-variables for the
concrete query-parameters.
A more realistic (still boild down) version of our select-statement is:
select * FROM TPERSON
where (upper(NAME) like 'MIL%' or (NAME is null))
and (upper(FIRSTNAME) like 'MICH% or (FIRSTNAME is null))
and ...;
thank you for time..
email: [email protected] -
Creation of function based index using escape
Hello,
I have the following SQL, sometimes performing bad:
SELECT DISTINCT UPPER(A.PROCESSIDCODE), UPPER(A.RULENAME), CHARSET
FROM XIB_DETECT A, XIB_PROCESSIDPROPERTIES B, XIB_RULES C
WHERE ( A.KEY1 = :P1 OR ( :P1 like REPLACE(REPLACE(REPLACE(REPLACE(KEY1,'%', '\%'),'_', '\_'),'?', '_'),'*','%') escape '\' AND A.REGFLAGS1 = 'Y') OR A.KEY1 = '*' AND A.REGFLAGS1 = 'Y')
AND (A.KEY2 = :P2 OR ( :P2 like REPLACE(REPLACE(REPLACE(REPLACE(KEY2,'%', '\%'),'_', '\_'),'?', '_'),'*','%') escape '\' AND A.REGFLAGS2 = 'Y') OR (A.KEY2 IS NULL AND A.REGFLAGS2 IS NULL ) )
AND (A.KEY3 = :P3 OR ( :P3 like REPLACE(REPLACE(REPLACE(REPLACE(KEY3,'%', '\%'),'_', '\_'),'?', '_'),'*','%') escape '\' AND A.REGFLAGS3 = 'Y') OR (A.KEY3 IS NULL AND A.REGFLAGS3 IS NULL ) )
AND (A.KEY4 = :P4 OR ( :P4 like REPLACE(REPLACE(REPLACE(REPLACE(KEY4,'%', '\%'),'_', '\_'),'?', '_'),'*','%') escape '\' AND A.REGFLAGS4 = 'Y') OR (A.KEY4 IS NULL AND A.REGFLAGS4 IS NULL ) )
AND (A.KEY5 = :P5 OR ( :P5 like REPLACE(REPLACE(REPLACE(REPLACE(KEY5,'%', '\%'),'_', '\_'),'?', '_'),'*','%') escape '\' AND A.REGFLAGS5 = 'Y') OR (A.KEY5 IS NULL AND A.REGFLAGS5 IS NULL ) )
AND (A.KEY6 IS NULL OR A.KEY6 = '*' AND REGFLAGS6 = 'Y')
AND (A.KEY7 IS NULL OR A.KEY7 = '*' AND REGFLAGS7 = 'Y')
AND (A.KEY8 IS NULL OR A.KEY8 = '*' AND REGFLAGS8 = 'Y')
AND (A.KEY9 IS NULL OR A.KEY9 = '*' AND REGFLAGS9 = 'Y')
AND (A.KEY10 IS NULL OR A.KEY10 = '*' AND REGFLAGS10 = 'Y')
AND ( ( A.PROCESSIDCODE IS NOT NULL AND UPPER(A.PROCESSIDCODE) = UPPER(B.PROCESSIDCODE) AND A.XLEVEL = B.XLEVEL AND B.ACTIVEFLAG = 'Y' )
OR ( A.RULENAME IS NOT NULL AND UPPER(A.RULENAME) = UPPER(C.RULENAME) AND A.XLEVEL = C.XLEVEL AND C.ACTIVEFLAG = 'Y' ) );
Now I want to create a function based index on the key1 column:
CREATE INDEX xib_detect_ix ON xib_detect (REPLACE(REPLACE(REPLACE(REPLACE(KEY1,'%', '\%'),'_', '\_'),'?', '_'),'*','%') escape '\') TABLESPACE ... ONLINE;
However, this is not working with "escape" '\', throwing: ORA-00907: missing right parenthesis
Any idea how to create an index on this construct with "escape"?
Database version is 10.2.0.3.
Thanks a lot.
Regards
OliverHi,
You can get the "missing right parenthesis" error for many different syntax errors.
In this case, you really are missing a right parenthesis. Your statement has 5 left '('s, but only 4 right ')'s. It's easy to see this if you format your code:
CREATE INDEX xib_detect_ix
ON xib_detect ( REPLACE ( REPLACE ( REPLACE ( REPLACE ( KEY1
escape '\'
ESCAPE is an option that you can use with the LIKE operator. It gives you a mechanism for cancelling the special meaning of symbols like '%'. You're not using the LIKE operator to create the index. You're only using REPLACE, and no characters have any special meaning in REPLACE, so there's no way (or reason) to escape them. Use ESCAPE in queries that use LIKE, when appropriate. -
Function-Based Indexes for 8.1.6 SE and 9iAS
I have installed the 9iAS Portal into a 8.1.6 SE database, and I cannot get the Function-Based Index feature to turn on. I have set QUERY_REWRITE_INTEGRITY=trusted, QUERY_REWRITE_ENABLED=true and COMPATIBLE="8.1.0.0.0". The feature will still not enable.
I have 2 questions:
1. Is there anything else I can do to turn this feature on.
2. If not, do I have to upgrade to 8.1.7 or to 8.1.* Enterprise Edition to make use of this feature.Could you give the statement for the index you have used, the query you try to do and a description of columns and datatypes of the table? How do you know/check that is doesn't work? Execution plan, errors?...
-
FUNCTION-BASED INDEX ( ORACLE 8I NEW FEATURE )
제품 : ORACLE SERVER
작성날짜 : 2004-08-16
FUNCTION-BASED INDEX ( ORACLE 8I NEW FEATURE )
==============================================
SCOPE
10g Standard Edition(10.1.0) 이상 부터 Function-based Index 기능이 지원된다.
Explanation
1. 개요
Function-based index는, 함수(function)이나 수식(expression)으로 계산
된 결과에 대해 인덱스를 생성하여 사용할 수 있는 기능을 제공한다.
질의 수행 시 해당 함수나 수식을 처리하여 결과를 가져 오는 것이 아니라,
인덱스 형태로 존재하는 미리 계산되어 있는 결과를 가지고 처리하므로
성능 향상을 기할 수 있다.
2. 제약사항
1) aggregate function 에 대한 function-based index 생성 불가.
(예 : sum(...) )
2) LOB, REF, nested table 컬럼에 대한 function-based index 생성 불가.
3. 주요 특징
1) cost-based optimizer에 의해 사용됨.
2) B*Tree / bitmap index로 생성 가능.
3) 산술식 (arithmetic expression), PLSQL function, SQL built-in
function 등에 적용 가능.
4) 함수나 수식으로 처리된 결과에 대한 range scan 가능
5) NLS SORT 지원
6) SELECT/DELETE를 할 때마다 함수나 수식의 결과를 계산하는 것이 아니라
INSERT/UPDATE 시 계산된 값을 인덱스에 저장.
7) 질의 속도 향상
8) object column이나 REF column에 대해서는 해당 object에 정의된
method에 대해 function-based index 생성 가능.
4. 생성 방법
CREATE [UNIQUE | BITMAP ] INDEX <index_name>
ON <tablename> (<index-expression-list>)
<index-expression-list> -> { <column_name> | <column_expression> }
예) CREATE INDEX EMP_NAME_INDEX ON EMP (UPPER(ENAME));
CREATE INDEX EMP_SAL_INDEX ON EMP( SAL + COMM, empno);
* Function-based index를 생성하기 위해서는 QUERY REWRITE 권한이
부여 되어 있어야만 한다.
예) GRANT QUERY REWRITE TO SCOTT;
5. Function-Based Index 사용을 위한 사전 작업
1) Function-based index는 cost based optimizer에서만 사용 가능하므로,
테이블에 대해 미리 analyze 해 주는 것이 바람직하다.
그리고 init 파일에서 OPTIMIZER_MODE 를 FIRST_ROWS 나 ALL_ROWS 등으
로 지정하거나 HINT 등을 사용하여 cost based optimizer가 사용되도록
한다.
2) init 파일에서 COMPATIBLE 파라미터 값을 8.1 이상으로 설정되어 있어야
한다.
( 예 : COMPATIBLE = 8.1.6 )
3) session/instance level 에서 QUERY_REWRITE_ENABLED 값이 TRUE 지정
되어 있어야 한다.
( 예 : ALTER SESSION SET QUERY_REWRITE_ENABLED = TRUE; )
6. 예제
1) init 파라미터에서 다음과 같이 지정
compatible = 8.1.6 (반드시 8.1이상이어야 한다)
query_rewrite_enabled = true
query_rewrite_integrity = trusted
2) SCOTT 유저에서 function_based_index 생성
create index idx_emp_lower_ename
on emp
( lower(ename) ) ;
3) EMP table analyze
analyze table emp compute statistics ;
4) PLAN_TABLE 생성
@ ?/rdbms/admin/utlxplan.sql
5) Cost based optimizer 선택
alter session set optimizer_mode = FIRST_ROWS ;
6) Query 실행
explain plan set statement_id='qry1' FOR
select empno, ename
from emp
where lower(ename) = 'ford' ;
7) PLAN 분석
SELECT LPAD(' ',2*level-2)||operation||' '||options||' '||object_name query_plan
FROM plan_table
WHERE statement_id='qry1'
CONNECT BY prior id = parent_id
START WITH id = 0 order by id ;
-> 결과
QUERY_PLAN
SELECT STATEMENT
TABLE ACCESS BY INDEX ROWID EMP
INDEX RANGE SCAN IDX_EMP_LOWER_ENAME
7. 결론
Function-based index는 적절하게 사용될 경우 성능상의 많은 이점을 가져
온다. Oracle8i Designing and Tuning for Performance에서도 가능한 한
Function-based index를 사용하는 것을 권장하고 있으며, LOWER(), UPPER()
등의 함수를 사용하여 불가피하게 FULL TABLE SCAN을 하는 경우에 대해서도
효과적으로 처리해 줄 수 있는 방안이라 할 수 있다.
Reference Documents
-------------------Partha:
From the Oracle8i Administrators Guide:
"Table owners should have EXECUTE privileges on the functions used in function-based indexes.
For the creation of a function-based index in your own schema, you must be
granted the CREATE INDEX and QUERY REWRITE system privileges. To create
the index in another schema or on another schemas tables, you must have the
CREATE ANY INDEX and GLOBAL QUERY REWRITE privileges."
Hope this helps.
Peter -
Query not considering function based index in oracle 11g
I have a query which used Function Based Index when run in oracle 9i but when I run the same query
without any changes, it does not consider index. Below is the query:
SELECT distinct patient_role.domain_key, patient_role.patient_role_key,
patient_role.emergency_contact_name,
patient_role.emergency_contact_phone, patient_role.emergency_contact_note,
patient_role.emergency_contact_relation_id,
patient_role.financial_class_desc_id, no_known_allergies, patient_role.CREATED_BY,
patient_role.CREATED_TIMESTAMP,
patient_role.CREATED_TIMESTAMP_TZ, patient_role.UPDATED_BY, patient_role.UPDATED_TIMESTAMP,
patient_role.UPDATED_TIMESTAMP_TZ,
patient_role.discontinued_date
FROM encounter, patient_role
WHERE patient_role.patient_role_key = encounter.patient_role_key
AND UPPER(TRIM(leading :SYS_B_0 from encounter.account_number)) = UPPER(TRIM(leading :SYS_B_1 from
:SYS_B_2))
AND patient_role.discontinued_date IS null
AND encounter.discontinued_date IS null ;
Index definition:
CREATE INDEX "user1"."IX_TRIM_ACCOUNT_NUMBER" ON "user1."ENCOUNTER" (UPPER(TRIM(LEADING
'0' FROM "ACCOUNT_NUMBER")), "PATIENT_ROLE_KEY", "DOMAIN_KEY", "DISCONTINUED_DATE")
PCTFREE 10 INITRANS 2 MAXTRANS 255 COMPUTE STATISTICS
STORAGE(INITIAL 65536 NEXT 1048576 MINEXTENTS 1 MAXEXTENTS 2147483645
PCTINCREASE 0 FREELISTS 1 FREELIST GROUPS 1
BUFFER_POOL DEFAULT)
TABLESPACE "user1"
Database : Oracle 11g (11.2.0.3)
O/S : Linux 64 bit (the query does not consider index even on windows os)
Any suggestions?
-Onkar
Edited by: onkar.nath on Jul 2, 2012 3:32 PMOnkar,
I don't appreciate you posting this question in several forums at the same time.
If I would know you also posted this on Asktom, I wouldn't even have bothered.
As to your 'issue':
First of all: somehow cursor_sharing MUST have been set to FORCE. Oracle is a predictable system, not a fruitmachine.
Your statement the '0' is replaced by a bind variable anyway is simply false. If you really believe it is not false, SUBMIT a SR.
But your real issue is not Oracle: it is your 'application', which is a mess anyway. Allowing for alphanumeric numbers is a really bad idea.
Right now you are already putting workaround on workaround on workaround on workaround.
Issue is the application: it is terminal., and you either need to kill it, or to replace it.
Sybrand Bakker
Senior Oracle DBA -
Oracle documentation on "How Function-Based Indexes Work" states that for the creation of a function-based index in the user's own schema, the user must be granted the QUERY REWRITE system privileges. And MUST have the following initialization parameters defined to create a function-based index:
QUERY_REWRITE_INTEGRITY set to TRUSTED
QUERY_REWRITE_ENABLED set to TRUE.
I have created a function-based unique index, which uses the SQL function DECODE(). But the user doesn't have the QUERY REWRITE sytem privilege. The user has the following privileges:
CREATE PROCEDURE
CREATE SEQUENCE
CREATE SESSION
CREATE TABLE
CREATE TRIGGER
CREATE VIEW
And also the initialization parameters for QUERY_REWRITE_INTEGRITY and QUERY_REWRITE_ENABLED are set to their DEFAULT values as follows:
QUERY_REWRITE_INTEGRITY set to ENCFORCED
QUERY_REWRITE_ENABLED set to FALSE.
Note: The index is an unique index for data integrity purpose. I am using Oracle 9.2.0.6 version.
Kindly explain me the reason how the function-based index is created without the system privilege and the initialization parmaters defined as stated in the Oracle9i Database Administrator's Guide Release 2 (9.2).You can change those parameter at session level as well.
Following link would be helpful:
http://asktom.oracle.com/pls/ask/f?p=4950:8:2552324147195810457::NO::F4950_P8_DISPLAYID,F4950_P8_CRITERIA:667694821129
Jaffar -
Function-based Index and an OR-condition in the WHERE-clause
We have some problems with functin-based indexes and
the or-condition in a where-clause.
(We use oracle 8i (8.1.7))
create table TPERSON(ID number(10),NAME varchar2(20),...);
create index I_NORMAL_TPERSON_NAME on TPERSON(NAME);
create index I_FUNCTION_TPERSON_NAME on TPERSON(UPPER(NAME));
The following two statements run very fast on a large table
and the execution-plan asure the usage of the indexes
(-while the session is appropriate configured and the table is analyzed):
1) select count(ID) FROM TPERSON where upper(NAME) like 'MIL%';
2) select count(ID) from TPERSON where NAME like 'Mil%' or (3=5);
In particular we see that a normal index is used while the where-clause contains
an OR-CONDITION.
But if we try the similarly select-statement
3) select count(ID) FROM TPERSON where upper(NAME) like 'MIL%' or (3=5);
the CBO will not use the function-index.
(This behavior we only expect with views but not with indexes.)
We ask for an advice like an hint, which enable the CBO-usage
of function-based indexes in connection with OR.
This problem seems to be artificial because it contains this dummy logic:
or (3=5).
This steams from an prepared statement, where this kind of boolean
flag reduce the amount of different select-statements needed for
covering the hole business-logic, while using bind-variables for the
concrete query-parameters.
A more realistic (still boild down) version of our prepared select-statement run in
SQL Plus:
define x_name = 'MIL%';
define x_firstname = '';
select * FROM TPERSON
where (upper(NAME) like '&x_name' or ( '&x_name' = ''))
and (upper(FIRSTNAME) like '&x_firstname' or ('&x_firstname' = ''))
and ...;
In particular we dont refernce the tablecolumn , but the QUERY-Parameter
yield the second boolean value in the or-condition.
The problem is that this condition ('&x_name' = '') dont use any index.
thanks a lot for spending your time with this problemTry
SELECT /*+ RULE */
as your hint. I don't have the book with me, but this last weekend I read a section about your very problem. The book was a Oracle Press gold cover about Oracle 8i Performance tuning. If you e-mail me I can quote you the chapter when I get home Friday. -
Unable to create function based Index
Hi All,
I created a function as below:
create or replace function eqx_oklb_term_date_nvl(pin_term_date date)
return date
deterministic
is
l_sub_date date := sysdate+1;
l_return_value date := l_sub_date;
begin
l_return_value := nvl(pin_term_date, l_sub_date);
return l_return_value;
exception
when others
then
l_return_value := l_sub_date;
return l_return_value;
end eqx_oklb_term_date_nvl;
Now trying to create a function based index using below code:
create index EQX_OKC_K_LINES_B_N4 on OKC.OKC_K_LINES_B(EQX_OKLB_TERM_DATE_NVL(DATE_TERMINATED))
logging
tablespace EQIXDATA
noparallel;
Encountered Error:
SQL Error: ORA-00904: "EQX_OKLB_TERM_DATE_NVL": invalid identifier
00904. 00000 - "%s: invalid identifier"
*Cause:
*Action:
I can successfully query dba_objects for the function.
Owner Object_name object_id object_type last_ddl_time status
APPS EQX_OKLB_TERM_DATE_NVL 11764623 FUNCTION 3/4/2013 9:44:57 PM VALID
I can also query the function using dual.
select eqx_oklb_term_date_nvl(null) nvl_date from dual;
nvl_date
3/5/2013 9:53:59 PM
I have given grants of the function to both schemas APPS/OKC
grant all on eqx_oklb_term_date_nvl to okc;
grant all on eqx_oklb_term_date_nvl to apps;
The column date_terminated in table okc_k_lines_b is a date. I've checked that.
Stuck here. Please help.
Thanks in advance,
RahulHi,
To follow up, the below code resolved the issue:
create index EQX_OKC_K_LINES_B_N4 on okc_k_lines_b(apps.eqx_oklb_term_date_nvl(date_terminated))
logging
tablespace eqixdata
noparallel;
-- qualifying the custom function name with schema name resolved the issue.
Thanks,
Rahul -
Function Based Index on Date Column
Hi All,
I need to execute a query like this :
SELECT * FROM ORDERS WHERE APPROVE_DATE IS NULL
I read anywhere that this will cause unnecessary FTS so that I should create function based index.
I have tried one below , but not sure that this is correct approach :
CREATE INDEX idx_1
ON ORDERS (NVL(APPROVE_DATE, '01-JAN-1900'));
SELECT * FROM ORDERS WHERE NVL(APPROVE_DATE, '01-JAN-1900') = '01-JAN-1900'
Is this a correct approach ?
Thank you,
xtantoA SQL_TRACE output will explain clearly what Justin has stated.
I have created a table T based on all_objects.
SQL> desc t
Name Null? Type
OWNER NOT NULL VARCHAR2(30)
OBJECT_NAME NOT NULL VARCHAR2(30)
SUBOBJECT_NAME VARCHAR2(30)
OBJECT_ID NOT NULL NUMBER
DATA_OBJECT_ID NUMBER
OBJECT_TYPE VARCHAR2(19)
CREATED DATE
LAST_DDL_TIME NOT NULL DATE
TIMESTAMP VARCHAR2(19)
STATUS VARCHAR2(7)
TEMPORARY VARCHAR2(1)
GENERATED VARCHAR2(1)
SECONDARY VARCHAR2(1)
CASE I_
SQL> select count(1) from t
2 /
COUNT(1)
934320
SQL> select count(1) from t where created is null
2 /
COUNT(1)
2376The number of null values in CREATED column is proportionately very small.
Now i execute the query without function based index.
select *
from t
where created is null
call count cpu elapsed disk query current rows
Parse 1 0.00 0.09 0 0 0 0
Execute 1 0.00 0.00 0 0 0 0
Fetch 160 0.04 0.10 0 12662 0 2376
total 162 0.04 0.19 0 12662 0 2376
Rows Execution Plan
0 SELECT STATEMENT GOAL: ALL_ROWS
2376 TABLE ACCESS GOAL: ANALYZED (FULL) OF 'T' (TABLE)And here is the query that uses the function based index
select *
from t
where nvl(created,to_date('01-01-1900','DD-MM-YYYY')) = to_date('01-01-1900','DD-MM-YYYY')
call count cpu elapsed disk query current rows
Parse 1 0.01 0.00 0 0 0 0
Execute 1 0.00 0.00 0 0 0 0
Fetch 160 0.01 0.01 0 698 0 2376
total 162 0.03 0.01 0 698 0 2376
Rows Execution Plan
0 SELECT STATEMENT GOAL: ALL_ROWS
2376 TABLE ACCESS GOAL: ANALYZED (BY INDEX ROWID) OF 'T' (TABLE)
2376 INDEX GOAL: ANALYZED (RANGE SCAN) OF 'T_FN_IDX' (INDEX)Its very obvious from the above output that the Function Based Index as increased the performance.
CASE II_
SQL> select count(1) from t
2 /
COUNT(1)
934320
SQL> select count(1) from t where created is null
2 /
COUNT(1)
202168Now the null values in the CREATED column is proportionately large than the first test case.
Now lets see without using the function based index
select *
from t
where created is null
call count cpu elapsed disk query current rows
Parse 1 0.00 0.00 0 0 0 0
Execute 1 0.00 0.00 0 0 0 0
Fetch 13479 0.46 0.71 2 25832 0 202168
total 13481 0.46 0.71 2 25832 0 202168
Rows Execution Plan
0 SELECT STATEMENT GOAL: ALL_ROWS
202168 TABLE ACCESS GOAL: ANALYZED (FULL) OF 'T' (TABLE)Now iam trying to use the function based index
select *
from t
where nvl(created,to_date('01-01-1900','DD-MM-YYYY')) = to_date('01-01-1900','DD-MM-YYYY')
call count cpu elapsed disk query current rows
Parse 1 0.00 0.00 0 0 0 0
Execute 1 0.00 0.00 0 0 0 0
Fetch 13479 0.54 0.84 0 33826 0 202168
total 13481 0.54 0.84 0 33826 0 202168
Rows Execution Plan
0 SELECT STATEMENT GOAL: ALL_ROWS
202168 TABLE ACCESS GOAL: ANALYZED (FULL) OF 'T' (TABLE)Its obvious from the result that oracle has decided to go for a FULL TABLE SCAN even when an index was available.
So just having a function based index is not going to increase the query performance. There are lot of other factors to be considered as stated above.
Thanks,
Karthick. -
Function Based index getting disabled frequently
I am facing some error like “ORA-30554: function-based index ORADB1.FUN_INDX1 is disabled” in the development database. I verified that the function which is referred by the index is valid. Once I even got the tedious generic error ORA-600 because of this. I referred the metalink and advised to drop and recreate the index
Dropping and recreating the index will solve the issue for 2-3 days and again the same will be repeated. So what I did is made the index unusable as it will not affect the other application activities. Can anybody give a clue on this issue?I am facing some error like “ORA-30554:
function-based index ORADB1.FUN_INDX1 is disabled” Cause: An attempt was made to access a function-based index that has been marked disabled because the function on which the index depends has been changed.
Action: Perform one of the following actions: -- drop the specified index using the DROP INDEX command -- rebuild the specified index using the ALTER INDEX REBUILD command -- enable the specified index using the ALTER INDEX ENABLE command -- make the specified index usable using the ALTER INDEX UNUSABLE command -
Function Based Index MOD(column_name,8)
For a function based index (MOD(column_name,8), the query is not using it. Do anyone have a solution to it? The table is having millions of rows.
Oracle only uses indexes if the number of returned rows is less than (i think) 4%. In your case the number of rows is 12,5% so Oracle will never use this index unless you force it
-
Function-Based Index enabling.
Hi...
I'm trying to create a function-based index along the lines of:
CREATE INDEX x_ssn4
ON table_y(SUBSTR(ssn,6,4))
UNRECOVERABLE;
...so as to be able to query the final 4 digits of social security numbers. Problem is that the above elicits an ORA-00439 "feature not enabled" message. I'm running 8.1.6 and have tried setting the Oracle parameter QUERY_REWRITE_ENABLED to 'TRUE' via an ALTER SESSION command, but to no avail.
Anyone know how to 'turn the feature on'?
Thanks, Rob<BLOCKQUOTE><font size="1" face="Verdana, Arial">quote:</font><HR>Originally posted by Rick Post:
I've always done it by logging on as SYS and executing a 'grant query rewrite to myuser'.
<HR></BLOCKQUOTE>
Thanks... but turns out that the privilege is not really the issue, as the ALTER SESSION command works. I figured out that the problem was the setting for COMPATIBLE. It pointed to 8.0.0 instead of 8.1.x which is what was needed to permit function-based indexing.
~Rob
null -
Function-based index error due to fine-grained security
Hi, i'm working on Oracle version 9.2.0.5.
I'm trying to create a function-based index but i'm getting an error due to fine-grained security. I checked resource_view but if i'm not wrong I should have all necessary roles. I also added xdbadmin to this user to be sure.
I tried also to alter my session but it didn't worked.
Connected to Oracle9i Enterprise Edition Release 9.2.0.5.0
Connected as test_ste
SQL>
SQL> create index fbidx_schede_xml
2 on schede_progetti_xml p
3 (p.PROGETTO.extract('/Project/Elenco_unita/Unita/Responsabile/Cognome/text()').getStringVal());
create index fbidx_schede_xml
on schede_progetti_xml p
(p.PROGETTO.extract('/Project/Elenco_unita/Unita/Responsabile/Cognome/text()').getStringVal())
ORA-28133: full table access is restricted by fine-grained security
ORA-06512: at "SYS.XMLTYPE", line 0
ORA-06512: at line 1
SQL>
SQL> alter session set query_rewrite_enabled = true;
Session altered
SQL> alter session set query_rewrite_integrity = trusted;
Session altered
SQL> create index fbidx_schede_xml
2 on schede_progetti_xml p
3 (p.PROGETTO.extract('/Project/Elenco_unita/Unita/Responsabile/Cognome/text()').getStringVal());
create index fbidx_schede_xml
on schede_progetti_xml p
(p.PROGETTO.extract('/Project/Elenco_unita/Unita/Responsabile/Cognome/text()').getStringVal())
ORA-28133: full table access is restricted by fine-grained security
ORA-06512: at "SYS.XMLTYPE", line 0
ORA-06512: at line 1
SQL> select * from user_role_privs;
USERNAME GRANTED_ROLE ADMIN_OPTION DEFAULT_ROLE OS_GRANTED
TEST_STE CONNECT NO YES NO
TEST_STE CTXAPP NO YES NO
TEST_STE RESOURCE NO YES NO
TEST_STE XDBADMIN NO YES NO
SQL> This are ACL on my schema:
<ACL>
<acl description="Private:All privileges to OWNER only and not accessible to others" xmlns="http://xmlns.oracle.com/xdb/acl.xsd" xmlns:dav="DAV:"
xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:schemaLocation="http://xmlns.oracle.com/xdb/acl.xsd http://xmlns.oracle.com/xdb/acl.xsd">
<ace>
<principal>dav:owner</principal>
<grant>true</grant>
<privilege>
<all/>
</privilege>
</ace>
</acl>
</ACL>I tried to create a similar function-based index on Oracle 10.2.0.3 without any problem and without touching any ACL, is an Oracle 9.2.0.5 problem?
Thanks for your attention.I didn't really (production wise)work yet with VPD. I know a lot is based on DBMS_RLS and I guess (IF it is VPD related) it should be to hard to find in the doc's how you could check what is beyond your privileges. As a DBA I noticed that even the dba account SYSTEM isn't always allow to export the full content for the tables anymore.
There is a privilege that grants you all access that you need, despite the fact that you are not allowed to read certain rows from a table. Look it up.
In all, as I said, it looks like account is not allowed to see all data from a table. In that respect it sounds logical that you also are, in that case, not allowed to build a function based index on that data -
Oracle 8i Function-based index
Hi,
i have problem with making Oracle8i to use function-based index. I am using version 8.1.6 Enterprise Edition.
So here is the test I did
CREATE INDEX first_name_index ON customer ( UPPER(first_name)) ;
alter session set QUERY_REWRITE_ENABLED = TRUE;
alter session set QUERY_REWRITE_INTEGRITY=TRUSTED;
ANALYZE TABLE customer COMPUTE STATISTICS;
alter index first_name_index compute statistics;
Everything seemed to be as required by Oracle but it doesn't use this function-based index when I make
select *
from customer
where upper(first_name) like 'J%';
I test it on large table and with table with few hundred rows. I don't have NULLs in that field.
Can anyone help me with this.I would not create an index to have it prepared for an ORDER BY. An index is quite costly in DML opperations and space as well. More, a function based index will be costlier as the function has to be called for every read and/or write.
Do not forget that indexes a created for a direct access to data and not for sorting purposes.
George
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