Function based indexes in Data Modeler 3.0

Trying to create a function based index in DATA MODELER 3.0 but cannot find a way to do it. When I reverse engineer (import from DATA DICTIONNARY) an existing table that contains such an object, the index appears in the physical model as a regular index. I guess this functionnality is not yet available...
Thanks.

Hi,
You can create a function-based Index by going to the Properties dialog for the Index in the Relational model (not the Physical model). If you select the Index Expression tick box, you can then enter the expression into the Expression text area.
David

Similar Messages

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,
xtanto

A 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 indexes info,pls let me know data dictionary table name?

Hi,
pls let me know,Where can we find Function based index information ,that is data dictionary table name,.
that is information like function used, column name.
Thanks,
KUmar.

all_ind_expressions

Function-based indexes

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

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,
Rahul

Hi,
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

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.

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

Impdp not importing function based index correctly.

We noticed that a process running in our develop database was running much faster than in the production database. After investigating we found that on the development database the process was using an index on the main large table and on the production database the index was ignored and full table scans of the large table were being used.
The data in the tables was the same, statistics were up-to-date, etc. Looking closer we saw that the index on the production database was function based because it had the DESC keyword on one column in the index. On the development database all columns of the index were ASC and thus it was a "normal" index. This was very confusing since we had just refreshed the development database from production using expdp/impdp. I ran impdp with the sqlfiles option to capture the DDL from the export file for the index in question from the production database:
CREATE UNIQUE INDEX "SYSADM"."PS_SF_1098_ITEM" ON "SYSADM"."PS_SF_1098_ITEM" ("EMPLID", "SF_TIN", "CALENDAR_YEAR", "SEQ_NO" DESC, "DTL_SEQ_NBR")
PCTFREE 10 INITRANS 2 MAXTRANS 255
STORAGE(INITIAL 40960 NEXT 1048576 MINEXTENTS 1 MAXEXTENTS 2147483645
PCTINCREASE 0 FREELISTS 1 FREELIST GROUPS 1 BUFFER_POOL DEFAULT)
TABLESPACE "PSINDEX" ;
I then dropped the table/index in the development database and reimported just this one table. Sure enough, the index wasn't created as a function based index (no DESC keyword on SEQ_NO column):
CREATE UNIQUE INDEX "SYSADM"."PS_SF_1098_ITEM" ON "SYSADM"."PS_SF_1098_ITEM" ("EMPLID", "SF_TIN", "CALENDAR_YEAR", "SEQ_NO", "DTL_SEQ_NBR")
PCTFREE 10 INITRANS 2 MAXTRANS 255 COMPUTE STATISTICS
STORAGE(INITIAL 40960 NEXT 1048576 MINEXTENTS 1 MAXEXTENTS 2147483645
PCTINCREASE 0 FREELISTS 1 FREELIST GROUPS 1 BUFFER_POOL DEFAULT)
TABLESPACE "PSINDEX" ;
I've researched this extensively and can't find any information on why this is happening. Any ideas before I open a SR?
BTW.... version is 11.1.0.7 patchset 31 on Windows Server 2003. Both dev and prod environments are identical.
Thanks,
Dan

Working on something else I noticed the following two "hidden" init.ora parameters in both my dev and production databases:
*._disable_function_based_index=TRUE
*._ignore_desc_in_index=TRUE
The first parameter explains why the index (function based) was being ignored in my production database. The second explains why the index is created without the DESC keyword in my dev database from an export from my prod database. I guess you do learn something new every day :)
These databases are used by Peoplesoft applications and I found several posts saying that function based indexes created by Peoplesoft were causing performance and/or data validity problems and users were instructed to set the above parameters so the FIB's weren't used. So, everything is working as expected/designed. I will contact Peoplesoft Tech Support to see if users are still encouraged to set the above parameters.
Dan

Function-based indexes don't seem to work in Oracle 8.1.5?

Hi,
What gives? What am I doing wrong? I have a table AIRPORT with a column (varchar2(64)) which I have specified a function based index for, but I can't get SQL wueries to use it!!!! the following SQL executes a FULL TABLE SCAN:
select /*+ index (a idx_upper_cityname) */ *
from airport a
where nls_upper(cityName) = 'dfdf'
...as does...
select *
from airport a
where nls_upper(cityName) = 'dfdf'
Table and index code is as follows:
CREATE TABLE airport
id NUMBER NOT NULL,
citycode VARCHAR2(3) NOT NULL,
cityname VARCHAR2(64) NOT NULL,
state VARCHAR2(2),
country VARCHAR2(2) NOT NULL,
region CHAR(1),
airportcode VARCHAR2(3) NOT NULL,
airportname VARCHAR2(64),
code VARCHAR2(4)
drop index idx_upper_cityname
CREATE INDEX idx_upper_cityname ON airport nls_upper(substr(cityName, 0, 64) )
Environment is as follows:
Oracle8i v8.1.5 running on WinNT v4.0 (SP 5)
Client is running on the same machine
thanks in advance,
Alexander

New data point: when I set the handler in my logging.properties file thusly,
org.apache.catalina.core.ContainerBase.[Catalina].[info-dev].[/infoisland].level = ALL
org.apache.catalina.core.ContainerBase.[Catalina].[info-dev].[/infoisland].handlers = java.util.logging.ConsoleHandlerI get 0 bytes in the info-dev log (which used to have the aforementioned expception in it). Where is my console going?

Importing error: related to function-based indexes?

I've come across a strange error. I've got a user that has an export dump file who wants me to import the data into a new database. (Its an Oracle 10G database.)
When I use the 'imp' command, the table import completes successfully, but I end up receiving the following warnings:
IMP-00003: oracle error 942 encountered
ORA-00942: table or view does not exist
IMP-00017: following statement failed with ORACLE error 942
"CREATE INDEX "X" on "Y" (TO_CHAR("Z",'yyyymmdd')) P"
"CTFREE 10 INITRANS 2 MAXTRANS 255 STORAGE(INITIAL 3145728 FREELISTS 1 FREEL"
"IST GROUPS 1 BUFFER_POOL DEFAULT) TABLESPACE "TBSPC" LOGGING"
The table itself seems to have been imported correctly; and all data rows exist. Its just the index that isn't being imported/rebuilt. (Other indexes on the same table were imported properly.)
The only thing that I could find that seems odd is that this index uses functions (the "TO_CHAR" in the index above). All of the other indexes on the table refer to basic fields. And I can rebuild the index manually.
Is the 'imp' command able to handle function-based indexes? Is there some parameter than I need to set to allow it to import these indexes?
(I know the more efficient thing to do would be to do an import with no indexes and rebuild them later...)
Edited by: user588235 on Dec 9, 2009 5:16 PM

Function based indexes should be supported. If it is exported, then it should be able to be imported. This just seems like a weird case. Have you tried to create a different table and then create a function based index on that table then see if exp/imp work?Yes, I have tried creating new versions of the tables (both with and without function-based indexes).
During my tests, I found that I can recreate the problem if I create the table in Oracle 9 and import it into Oracle 10; the problem doesn't occur when importing/exporting between Oracle9->Oracle9 or Oracle10->Oracle10. (However, the user told me that this was an export from Oracle 10.)
One other thing: I've noticed that if, instead of importing into a user account, I import into the system account, it works with no problems. For example:
imp userid='sys/xyz as sysdba' file=mydata.dmp fromuser=use1 touser=use2 ->Results in warnings while reading indexes
imp userid='sys/xyz as sysdba' file=mydata.dmp fromuser=use1 touser=sys ->works with no warning
This makes me suspect that its a problem with the permissions that have been granted. (I've granted 'create any index' and 'query rewrite' to the user account however.)
Not to change the issue, but since this is 10g, have you tried using datapump to expdp/impdp the same information?Might be an option; problem is, I'm dealing with a legacy system that was set up to use 'imp/exp', so altering backup and restore methods will require a lot of work.

URGENT - Function based indexes

Hi,
I have a table with huge amount of data and hence I have created
a function-based (Upper) index on one of the character NOT
NULL field which is very likely to be used for query purposes.
First of all though I can create ordinary normal field based
indexes in my user I cannot create a function-based index, why
That had to be created thru SYS user. Secondly I my query
invloving this function is not using the index and instead doing
a full-table scan. Problem outlined below :
Table : PLZPOST, USER / OWNER : PARTNER, FIELD : ORT
INDEX created on UPPER(ORT) in SYS user -
Create index upper_plz_ort on partner.plzpost (upper(ort))
When I give any of the following queries instead of using the
resp. index as mentioned in Oracle DOC it just does a full table
scan (checked thru Explain Plan) :
select * from PLZPOST where upper(ort) is not null;
select * from PLZPOST where upper(ort) like upper('saar%')
select * from PLZPOST where upper(ort) = 'SAARBRUECKEN'
etc etc
If anyone has used Function-based indexes in Oracle 8i could you
please tell me where am I going wrong. Is it because my Table
belongs to PARTNER and Index to SYS (tried running the above
queries under SYS user also but still did not work) ?? If so how
can I grant access on an Index to PARTNER from SYS ??
Your help would be greatly appreciated.
Thanks in advance,
Cheers
Rashmi
null

<BLOCKQUOTE><font size="1" face="Verdana, Arial">quote:</font><HR>Originally posted by Rashmi Rungta ([email protected]):
Hi,
I have a table with huge amount of data and hence I have created
a function-based (Upper) index on one of the character NOT
NULL field which is very likely to be used for query purposes.
First of all though I can create ordinary normal field based
indexes in my user I cannot create a function-based index, why
That had to be created thru SYS user. Secondly I my query
invloving this function is not using the index and instead doing
a full-table scan. Problem outlined below :
Table : PLZPOST, USER / OWNER : PARTNER, FIELD : ORT
INDEX created on UPPER(ORT) in SYS user -
Create index upper_plz_ort on partner.plzpost (upper(ort))
When I give any of the following queries instead of using the
resp. index as mentioned in Oracle DOC it just does a full table
scan (checked thru Explain Plan) :
select * from PLZPOST where upper(ort) is not null;
select * from PLZPOST where upper(ort) like upper('saar%')
select * from PLZPOST where upper(ort) = 'SAARBRUECKEN'
etc etc
If anyone has used Function-based indexes in Oracle 8i could you
please tell me where am I going wrong. Is it because my Table
belongs to PARTNER and Index to SYS (tried running the above
queries under SYS user also but still did not work) ?? If so how
can I grant access on an Index to PARTNER from SYS ??
Your help would be greatly appreciated.
Thanks in advance,
Cheers
Rashmi<HR></BLOCKQUOTE>
null

Function Based Indexes - negative performance

Has anyone run across any cases where they have had issues with Function Based Indexes negatively impacting performance??
We are trying to use function based indexes in 9i (NLS_SORT=GENERIC_BASELETTER) and 10g (NLS_SORT=BINARY_CI) for case insensitivity.
We thought this was a decent solution until recently when testing with larger datasets. Any info is appreciated.
Thanks,

Just to clarify rreynoldson's first point:
All indexes will negatively impact inserts. Indexes, including function-based indexes, may or may not improve update and delete performance depending on whether the overhead of maintaining the index outweighs the benefit of being able to use the index to find the row(s) to update relatively quickly.
For user564260:
Assuming those parameters are set, make sure that you've gathered statistics on the function based index. If that doesn't resolve the problem, can you post a small test case that demonstrates the problem where you
- Create the table
- Create the indexes
- Populate it with data
- Run the query that you'd expect to use the FBI
- Post the explain plan
that would help us immensely.
Justin

Function based indexes on CLOB storage

On a 10gR2 database, with schema-less CLOB storage for an XMLType column:
(1) Can a function based index include a wildcard in the namespace ? Or do I need a new function based index for each specific namespace ?
(2) I must create a new function based index for each different element that I want an indexed search on ?
(3) What limit is there on the number of function based indexes per table ?
(4) I believe XQuery can include a wildcard for namespaces, but XPath 1.x can't. Can I create a function based index using XQuery, rather than XPath ?
Documents conforming to different versions of an XML schema will be present (schema versioning), but I want to search across all documents irrespective of a specific namespace - e.g. "Find any document with reference = 'some Value' , and amount = 1000".
CLOB storage is proposed, due to the need to handle documents from multiple versions of an XML schema. The knowledge of the XSD is not known at development time, but is user definable, and it must be possible to change the structure without system down time. Structured storage is not suitable, due to Oracle's requirement for downtime if the schema changes (CopyEvolve drops/recreates tables), and Oracle doesn't support schema collections, so you can't bind an XML column to multiple schemas.
Here is some sample code of what I'm trying to do:
create table BulkTest
ID NUMBER(10) not null primary key,
USERFIELDS XMLTYPE
create sequence S_BulkTest;
--Document conforming to version 1 of schema
INSERT INTO BulkTest(id, Userfields) VALUES
(S_BulkTest.Nextval,
'<?xml version="1.0" encoding="utf-8" ?>
<mt395 xmlns="urn:incident:mt395-1">
     <reference>FH12345678</reference>
     <relatedReference>FH23456789</relatedReference>
     <queries>Here is some query text.</queries>
     <narrative>Here is some narrative text.</narrative>
     <relatedMessageType>300</relatedMessageType>
     <relatedMessageDate>2005-03-29</relatedMessageDate>
     <direction>R</direction>
     <sessionNumber>1234</sessionNumber>
     <isn>123456</isn>
     <relatedMessageDescription>This is the deal where I bought USD 1 million for GBP at 1.76.</relatedMessageDescription>
     <otherParty>232332</otherParty>
</mt395>'
--Document conforming to version 2 of schema
INSERT INTO BulkTest(id, Userfields) VALUES
(S_BulkTest.Nextval,
'<?xml version="1.0" encoding="utf-8" ?>
<mt395 xmlns="urn:incident:mt395-2">
     <guid>0f9a08f6-b052-4693-baba-8f7dc881e7e8</guid>
     <reference>333333</reference>
     <queries>Another query</queries>
     <narrative>Some narrative</narrative>
     <direction>R</direction>
     <sessionNumber>1234</sessionNumber>
     <isn>223456</isn>
</mt395>'
--It seems I need to create a new index for each field I want to search on
create index iBulkTest_REFERENCE
on BulkTest
(extractValue(UserFields,'/mt395/reference', 'xmlns="urn:incident:mt395-1"'));
--And that a new index is required for each specifc namespace that is present
--Can't we include a wildcard in the namespace ?
create index iBulkTest_REFERENCE_2
on BulkTest
(extractValue(UserFields,'/mt395/reference', 'xmlns="urn:incident:mt395-2"'));
--If I want to query, I have to explicitly specify each namespace.
--Can't I specify a wildcard ?
--This will make it "fun" querying across namespaces!
select
id,
extractValue(UserFields,'/mt395/reference', 'xmlns="urn:incident:mt395-2"') As Reference,
t.userfields.getclobval() userfields
from bulktest t
WHERE extractValue(UserFields,'/mt395/reference', 'xmlns="urn:incident:mt395-2"') = '333333'

Andy
#1. You do not have scehma versioning here. Your model is totally incorrect. You shoud not change the namespace when versioning the XML Schema. You have 2 different and totally disjoint XML Schemas. The correct was to version, as distinct from evolve an XML Schema is to change the Schema Location Hint associated with your XML...
Eg
INSERT INTO BulkTest(id, Userfields) VALUES
(S_BulkTest.Nextval,
'<?xml version="1.0" encoding="utf-8" ?>
<mt395 xmlns="urn:incident:mt395" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:schemaLocation="urn:incident:mt395 mt395-1.xsd">
<reference>FH12345678</reference>
<relatedReference>FH23456789</relatedReference>
<queries>Here is some query text.</queries>
<narrative>Here is some narrative text.</narrative>
<relatedMessageType>300</relatedMessageType>
<relatedMessageDate>2005-03-29</relatedMessageDate>
<direction>R</direction>
<sessionNumber>1234</sessionNumber>
<isn>123456</isn>
<relatedMessageDescription>This is the deal where I bought USD 1 million for GBP at 1.76.</relatedMessageDescription>
<otherParty>232332</otherParty>
</mt395>'
--Document conforming to version 2 of schema
INSERT INTO BulkTest(id, Userfields) VALUES
(S_BulkTest.Nextval,
'<?xml version="1.0" encoding="utf-8" ?>
<mt395 xmlns="urn:incident:mt395 xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:schemaLocation="urn:incident:mt395 mt395-2.xsd">
<guid>0f9a08f6-b052-4693-baba-8f7dc881e7e8</guid>
<reference>333333</reference>
<queries>Another query</queries>
<narrative>Some narrative</narrative>
<direction>R</direction>
<sessionNumber>1234</sessionNumber>
<isn>223456</isn>
</mt395>'
This is the correct way of versioning an XML Schema. THe namespace stays the same, the SchemaLocationHint in the SchemaLocation tag changes.
Bear in mind that if you use the technique you are currently using you will make any path expressions you need to write absolutely unmaintaining and the processing of them very inefficient.
Some questions to consider
Node 'X' in namespace 'X' is never the same as Node 'X' in namespace 'Y'.
How would you write an Xpath or XQuery that targetted multiple versions, but not all versions ?
What happens if you have other documents that are really in a different namespace ? Using wildcards can you differentiate them..
From the problem you are describing and the terminolgy you are using it looks like you've been an early customer of Yukon. MSFT clearly didn't understand schema versioning in the early beta releases and used the 'change the namespace' schema for modelling schema versioning.
We do have some technology coming down the pipe which can address the issue, regardless of whether or not it is too late for you to correct the versioning scheme you have selected. However I cannot discuss that in a public forum. If you want to learn about these features and are prepared to enter an NDA with Oracle in order to do so please contact me directly. You can do this a number of ways...
Guess my email address @oracle.com
Post your email address here and I'll delete the post as soon as I have it..
Update your OTN Forum profile to include your email address
Open a TAR and post the tar number here. You can then softclose the tar as this is simply a method for me to get your contact info.

Function based indexes on object tables

Hi,
I am trying to create a function based index on an object table. I am getting the following error:
SQL> create index cell1_indx on cell1(create_cell1(id)) indextype is mdsys.spatial_index;
create index cell1_indx on cell1(create_cell1(id)) indextype is mdsys.spatial_index
ERROR at line 1:
ORA-29855: error occurred in the execution of ODCIINDEXCREATE routine
ORA-13249: internal error in Spatial index: [mdidxrbd]
ORA-13249: Error in Spatial index: index build failed
ORA-13249: Stmt-Execute Failure: SELECT num_rows from all_tables where owner='ASHE' and table_name=
'CELL1'
ORA-06512: at "MDSYS.SDO_INDEX_METHOD_9I", line 7
ORA-06512: at line 1
Here cell1 is an object table.
Is the procedure for creating function based indexes on object tables different from relational tables?
Chinni

One of the many new features in Oracle 8i is the Function-Based Index (we will refrain from using FBI, but only just). This allows the DBA to create indexes on functions or expressions; these functions can be user generated pl/sql functions, standard SQL functions (non-aggregate only) or even a C callout.
A classic problem the DBA faces in SQL Tuning is how to tune those queries that use function calls in the where clause, and result in indexes created on these columns not to be used.
Example
Standard B-Tree index on SURNAME with cost based optimizer
create index non_fbi on sale_contacts (surname);
analyze index non_fbi compute statistics;
analyze table sale_contacts compute statistics;
SELECT count(*) FROM sale_contacts
WHERE UPPER(surname) = 'ELLISON';
Execution Plan
0 SELECT STATEMENT Optimizer=CHOOSE (Cost=3 Card=1 Bytes=17)
1 0 SORT (AGGREGATE)
2 1 TABLE ACCESS (FULL) OF 'SALES_CONTACTS' (Cost=3 Card=16 Bytes=272)
Now we use a function based index
create index fbi on sale_contacts (UPPER(surname));
analyze index fbi compute statistics;
analyze table sale_contacts compute statistics;
SELECT count(*) FROM sale_contacts WHERE UPPER(surname) = 'ELLISON';
Execution Plan
0 SELECT STATEMENT Optimizer=CHOOSE (Cost=2 Card=1 Bytes=17)
1 0 SORT (AGGREGATE)
2 1 INDEX (RANGE SCAN) OF 'FBI' (NON-UNIQUE) (Cost=2 Card=381 Bytes=6477)
The function-based index has forced the optimizer to use index range scans (retuning zero or more rowids) on the surname column rather than doing a full table scan (non-index lookup). Optimal performance does vary depending on table size, uniqueness and selectivity of columns, use of fast full table scans etc. Therefore try both methods to gain optimal performance in your database.
It is important to remember that the function-based B*Tree index does not store the expression results in the index but uses an "expression tree". The optimizer performs expression matching by parsing the expression used in the SQL statement and comparing the results against the expression-tree values in the function-based index. This comparison IS case sensitive (ignores spaces) and therefore your function-based index expressions should match expressions used in the SQL statement where clauses.
Init.ora Parameters
The following parameter must be set in your parameter file: QUERY_REWRITE_INTEGRITY = TRUSTED
QUERY_REWRITE_ENABLED = TRUE
COMPATIBLE = 8.1.0.0.0 (or higher)
Grants
Grants To create function-based indexes the user must be granted CREATE INDEX and QUERY REWRITE, or alternatively be granted CREATE ANY INDEX and GLOBAL QUERY REWRITE. The index owner must have EXECUTE access on the function used for the index. If execute access is revoked then the function-based index will be "disabled" (see dba_indexes).
Disabled Indexes
If your function-based index has a status of "disabled" the DBA can do one of the following:
a) drop and create the index (take note of its current settings)
b) alter index enable, function-based indexes only, also use disable keyword as required
c) alter index unusable.
Queries on a DISABLED index fail if the optimizer chooses to use the index.Here is an example ORA error:
ERROR at line 1: ORA-30554: function-based index MYUSER.FBI is disabled.
All DML operations on a DISABLED index also fail unless the index is also marked UNUSABLE and the initialization parameter SKIP_UNUSABLE_INDEXES is set to true.
Some more Examples
CREATE INDEX expression_ndx
ON mytable ((mycola + mycolc) * mycolb);
SELECT mycolc FROM mytable
WHERE (mycola + mycolc) * mycolb <= 256;
..or a composite index..
CREATE INDEX example_ndx
ON myexample (mycola, UPPER(mycolb), mycolc);
SELECT mycolc FROM myexample
WHERE mycola = 55 AND UPPER(mycolb) = 'JONES';
Restriction & Rule Summary
The following restrictions apply to function based indexes. You may not index:
a) LOB columns
b) REF
c) Nested table column
d) Objects types with any of the above data types.
Function-based indexes must always follow these rules:
a) Cost Based optimizer only, must generate statistics after the index is created
b) Can not store NULL values (function can not return NULL under any circumstance)
c) If a user defined pl/sql routine is used for the function-based index, and is invalidated, the index will become "disabled"
d) Functions must be deterministic (always return the same value for a known input)
e) The index owner must have "execute" access on function used in the function-based index. Revocation of the privilege will render the index "disabled"
f) May have a B-Tree and Bitmap index type only
g) Can not use expressions that are based on aggregate functions, ie. SUM, AVG etc.
h) To alter a function-based index as enabled, the function used must be valid, deterministic and the signature of the function matches the signature of the function when it was created.
Joel P�rez

Function based indexes in Data Modeler 3.0

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