Descending primary key

Hello everyone.
Is there a way to create primary key with DESC order of its index?
I have a sql for MSSQL that looks like:
ALTER TABLE table_name ADD CONSTRAINT pk_name
PRIMARY KEY ( Column1 DESC, Column2 DESC, Column3 DESC)
How can I do that in Oracle?
I tried this:
ALTER TABLE table_name
ADD CONSTRAINT pk_name PRIMARY KEY
Column1 DESC
*, Column2 DESC*
*, Column3 DESC*
ENABLE;
but I got this error:
Error report:
SQL Error: ORA-00907: missing right parenthesis
*00907. 00000 - "missing right parenthesis"*
**Cause:*
**Action:*

You can't do it like this with primary key directly, but you can associate an index with the primary key constraint.
Please read this section (see link) and especially take a look at example 3 here:
http://download.oracle.com/docs/cd/B28359_01/server.111/b28310/indexes003.htm#i1006566
You can use ASC or DESC in the index create command then.
Edited by: hm on 08.09.2011 02:00

Similar Messages

Primary Key in Internal tables?

Hi all,
Im doing a ABAP- certification, so I need an exact answer , not the 'I think...' or 'it should...' answers.
I often heard the sentence 'every internal Table has a key, even if you dont define one!'. OK, I was told, that SAP takes the non-numeric fields, and bind them to the prim.-key.
But now I wrote this little program:
Report ZYX.
DATA: Begin of wa,
one type i,
two type i,
three type i,
End of wa.
DATA: it LIKE table of wa,
temp type i.
Do 100 times.
temp = temp + 1.
wa-one = temp.
wa-two = temp + 1.
wa-three = temp + 2.
enddo.
sort it descending.
WRITE: / wa-one,wa-two,wa-three.
Why doesnt it sort the table in ANY way descending?
why doesnt this table seems to have a primary key?
Is that a mistake by the SAP?

I think it means both
I copy here what I found in SAPHelp and you understand:
Die Standardschlüsselfelder eines strukturierten Zeilentyps sind alle Felder, die weder numerisch (i, p, f) noch selbst Tabellentypen sind. Der Standardschlüssel bei nicht-strukturiertem Zeilentyp ist die gesamte Tabellenzeile, falls der Zeilentyp selbst kein Tabellentyp ist. Falls es keine entsprechende Komponente gibt bzw. der Zeilentyp selbst ein Tabellentyp ist, bleibt der Standardschlüssel leer, was aber nur bei Standardtabellen möglich ist.

How to Create primary key index with duplicate rows.

Hi All,
While rebuilding an index on a table , I am getting error that there are duplicate rows in a table.
Searching out the reason led me to an interesting observation.
Please follow.
SELECT * FROM user_ind_columns WHERE table_name='SERVICE_STATUS';
INDEX_NAME     TABLE_NAME     COLUMN_NAME     COLUMN_POSITION     COLUMN_LENGTH     CHAR_LENGTH     DESCEND
SERVICE_STATUS_PK     SERVICE_STATUS     SUBSCR_NO_RESETS     2     22     0      ASC
SERVICE_STATUS_PK     SERVICE_STATUS     STATUS_TYPE_ID     3     22     0     ASC
SERVICE_STATUS_PK     SERVICE_STATUS     ACTIVE_DT     4     7     0     ASC
SERVICE_STATUS_PK     SERVICE_STATUS     SUBSCR_NO     1     22     0     ASC
SELECT index_name,index_type,table_name,table_type,uniqueness, status,partitioned FROM user_indexes WHERE index_name='SERVICE_STATUS_PK';
INDEX_NAME     INDEX_TYPE      TABLE_NAME     TABLE_TYPE     UNIQUENESS     STATUS     PARTITIONED
SERVICE_STATUS_PK     NORMAL     SERVICE_STATUS     TABLE     UNIQUE     VALID     NO
SELECT constraint_name ,constraint_type,table_name,status,DEFERRABLE,DEFERRED,validated,index_name
FROM user_constraints WHERE constraint_name='SERVICE_STATUS_PK';
CONSTRAINT_NAME     CONSTRAINT_TYPE     TABLE_NAME      STATUS     DEFERRABLE     DEFERRED     VALIDATED     INDEX_NAME
SERVICE_STATUS_PK     P     SERVICE_STATUS     ENABLED     NOT DEFERRABLE     IMMEDIATE VALIDATED     SERVICE_STATUS_PK
1. Using index scan:
SELECT COUNT (*)
FROM (SELECT subscr_no, active_dt, status_type_id, subscr_no_resets
FROM service_status
GROUP BY subscr_no, active_dt, status_type_id, subscr_no_resets
HAVING COUNT (*) > 1) ;
no rows returned
Explain plan:
Operation     OBJECT Name     ROWS     Bytes     Cost     OBJECT Node     IN/OUT     PStart     PStop
SELECT STATEMENT Optimizer MODE=CHOOSE          519 K          14756
FILTER
SORT GROUP BY NOSORT          519 K     7 M     14756
INDEX FULL SCAN     ARBOR.SERVICE_STATUS_PK     10 M     158 M     49184
2. Using Full scan:
SELECT COUNT (*)
FROM (SELECT /*+ full(s) */ subscr_no, active_dt, status_type_id, subscr_no_resets
FROM service_status s
GROUP BY subscr_no, active_dt, status_type_id, subscr_no_resets
HAVING COUNT (*) > 1) ;
71054 rows returned.
Explain Plan:
Operation     Object Name     Rows     Bytes     Cost     Object Node     In/Out     PStart     PStop
SELECT STATEMENT Optimizer Mode=CHOOSE          1           24123
SORT AGGREGATE          1
VIEW          519 K          24123
FILTER
SORT GROUP BY          519 K     7 M     24123
TABLE ACCESS FULL     ARBOR.SERVICE_STATUS     10 M     158 M     4234
Index SERVICE_STATUS_PK is a unique and composite primary key VALID index. And the constraint is ENABLED and VALIDATED still having duplicate rows in table.
How it is possible?
Is it an Oracle soft Bug??
Regards,
Saket Bansal

saket bansal wrote:
Values are inserted as single rows inserts through an GUI interface.And you still claim to have over 71K duplicate records, without the GUI getting any kind of errors?
That does not add up and can only be explained by a "bug".
I tried inserting a duplicate record but failed.
SQL> insert into service_status (select * from service_status where rownum <2);
insert into service_status (select * from service_status where rownum <2)
ERROR at line 1:
ORA-00001: unique constraint (ARBOR.SERVICE_STATUS_PK) violatedAre you really sure there is no other way data in this table is populated/manipulated in bulk?

Impact Of Primary Key

create table SEN_TEMP
E_NO   NUMBER not null,
E_NAME VARCHAR2(50),
E_TEAM VARCHAR2(50)
insert into sen_temp (E_NO, E_NAME, E_TEAM)
values (1, 'A1', 'T1')
insert into sen_temp (E_NO, E_NAME, E_TEAM)
values (2, 'A2', 'T2')
insert into sen_temp (E_NO, E_NAME, E_TEAM)
values (3, 'A3', 'T3')
Executing the Below
SELECT *
FROM sen_temp
where rownum = 1
order by e_no desc;
Output
E_NO   E_NAME E_TEAM
1          A1         T1
Now am Gng to Add a Primary Key Constraint On the Column E_no
alter table sen_temp add constraint pk_e_no primary key (e_no)
Now Am Executing the Same query
SELECT *
FROM sen_temp
where rownum = 1
order by e_no desc
But the
Output Is
E_NO   E_NAME E_TEAM
3          A3         T3
Can Anyone Tell me, the way how the primary key is affecting the query

Sen wrote:
k den, why its returning e-no as 3 after adding a primary key..Most likely the execution plan has changed due to the addition of the primary key. See my example below:
SQL> create table SEN_TEMP
2 (
3    E_NO   NUMBER not null,
4    E_NAME VARCHAR2(50),
5    E_TEAM VARCHAR2(50)
6 )
7 /
Table created.
SQL> insert into sen_temp (E_NO, E_NAME, E_TEAM)
2 values (1, 'A1', 'T1')
3 /
1 row created.
SQL> insert into sen_temp (E_NO, E_NAME, E_TEAM)
2 values (2, 'A2', 'T2')
3 /
1 row created.
SQL> insert into sen_temp (E_NO, E_NAME, E_TEAM)
2 values (3, 'A3', 'T3')
3 /
1 row created.
SQL> SELECT /*+gather_plan_statistics*/ *
2 FROM sen_temp
3 where rownum = 1
4 order by e_no desc;
      E_NO E_NAME                                             E_TEAM
         1 A1                                                 T1
1 row selected.
SQL> SELECT * FROM TABLE(DBMS_XPLAN.DISPLAY_CURSOR(null,null,'ALLSTATS LAST'));
PLAN_TABLE_OUTPUT
SQL_ID 8hajz83tnvwnw, child number 0
SELECT /*+gather_plan_statistics*/ * FROM sen_temp where rownum = 1
order by e_no desc
Plan hash value: 3862566870
| Id | Operation           | Name     | Starts | E-Rows | A-Rows |   A-Time   | Buffers | OMem | 1Mem | Used-Mem |
|   0 | SELECT STATEMENT    |          |      1 |        |      1 |00:00:00.01 |       3 |       |    |     |
|   1 | SORT ORDER BY      |          |      1 |      1 |      1 |00:00:00.01 |       3 | 73728 | 73728 |          |
|* 2 |   COUNT STOPKEY     |          |      1 |        |      1 |00:00:00.01 |       3 |       |    |     |
|   3 |    TABLE ACCESS FULL| SEN_TEMP |      1 |      3 |      1 |00:00:00.01 |       3 |       |    |     |
Predicate Information (identified by operation id):
   2 - filter(ROWNUM=1)
Note
   - dynamic sampling used for this statement (level=2)
25 rows selected.
SQL> alter table sen_temp add constraint pk_e_no primary key (e_no)
2 /
Table altered.
SQL> SELECT /*+gather_plan_statistics*/ *
2 FROM sen_temp
3 where rownum = 1
4 order by e_no desc;
      E_NO E_NAME                                             E_TEAM
         3 A3                                                 T3
1 row selected.
SQL> SELECT * FROM TABLE(DBMS_XPLAN.DISPLAY_CURSOR(null,null,'ALLSTATS LAST'));
PLAN_TABLE_OUTPUT
SQL_ID 8hajz83tnvwnw, child number 0
SELECT /*+gather_plan_statistics*/ * FROM sen_temp where rownum = 1
order by e_no desc
Plan hash value: 577902443
| Id | Operation                    | Name     | Starts | E-Rows | A-Rows |   A-Time   | Buffers |
|   0 | SELECT STATEMENT             |          |      1 |        |      1 |00:00:00.01 |       2 |
|* 1 | COUNT STOPKEY               |          |      1 |        |      1 |00:00:00.01 |       2 |
|   2 |   TABLE ACCESS BY INDEX ROWID| SEN_TEMP |      1 |      3 |      1 |00:00:00.01 |       2 |
|   3 |    INDEX FULL SCAN DESCENDING| PK_E_NO |      1 |      1 |      1 |00:00:00.01 |       1 |
Predicate Information (identified by operation id):
   1 - filter(ROWNUM=1)
Note
   - dynamic sampling used for this statement (level=2)
25 rows selected.See how in the first case Oracle did a full table scan and in the second case it used an index? That's why your results are different.

How to create one primary key for each vendor

Hi all
i am doing IDOC to jdbc scenario
i am triggering idoc from R/3 and the data is going into DB table vendor through XI.
structures are as follows:
sender side: ZVendorIdoc (this is a customized IDOC , if i triger IDOC for multiple vendors then it triggers only 1 idoc with multiple segment )
Receiver side:
DT_testVendor
    Table
        tblVendor
            action UPDATE_INSERT
            access                     1:unbounded
                cVendorName         1
                cVendorCode        1
                fromdate                1
                todate                    1
             Key1
                cVendorName         1
if i trigger idoc for multiple vendors ,for example vendor 2005,2006 and 2010 . then i can see that the only key comes from the very first field (2005) and the whole record for vendor 2005,2006 and 2010 goes into the table with this(2005) as a primary key
now again if i send data for these three vendor 2005, 2006 , 2010, in which record for the vendor 2005 is same and for 2006 and 2010 are different than it takes 2005 as a primary key and it does not update the data in the table.
my requirement is like this:   for each vendor there should be one unique key assigned.
                                          for above said example there should come three keys one for each vendor .
could you please help me how to do this???????????

Hi,
In Mapping Make the statement is 0-unbounded.For each vendor create a statement.This will solve your problem.
Regards,
Prakasu.M

Error While Deploying A CMP Entity Bean With A Composite Primary Key

Hello all,
I have a problem deploying CMP Entity beans with composite primary keys. I have a CMP Entity Bean, which contains a composite primary key composed of two local stubs. If you know more about this please respond to my post on the EJB forum (subject: CMP Bean Local Stub as a Field of a Primary Key Class).
In the mean time, can you please tell me what following error message means and how to resolve it? From what I understand it might be a problem with Sun ONE AS 7, but I would like to make sure it's not me doing something wrong.
[05/Jan/2005:12:49:03] WARNING ( 1896):      Validation error in bean CustomerSubscription: The type of non-static field customer of the key class
test.subscription.CustomerSubscriptionCMP_1530383317_JDOState$Oid must be primitive or must implement java.io.Serializable.
     Update the type of the key class field.
     Warning: All primary key columns in primary table CustomerSubscription of the bean corresponding to the generated class test.subscription.CustomerSubscriptionCMP_1530383317_JDOState must be mapped to key fields.
     Map the following primary key columns to key fields: CustomerSubscription.CustomerEmail,CustomerSubscription.SubscriptionType. If you already have fields mapped to these columns, verify that they are key fields.Is it enough that a primary key class be serializable or all fields have to implement Serializable or be a primitive?
Please let me know if you need more information to answer my question.
Thanks.
Nikola

Hi Nikola,
There are several problems with your CMP bean.
1. Fields of a Primary Key Class must be a subset of CMP fields, so yes, they must be either a primitive or a Serializable type.
2. Sun Application Server does not support Primary Key fields of an arbitrary Serializable type (i.e. those that will be stored
as BLOB in the database), but only primitives, Java wrappers, String, and Date/Time types.
Do you try to use stubs instead of relationships or for some other reason?
If it's the former - look at the CMR fields.
If it's the latter, I suggest to store these fields as regular CMP fields and use some other value as the PK. If you prefer that
the CMP container generates the PK values, use the Unknown
PrimaryKey feature.
Regards,
-marina

Logical standby and Primary keys

Hi All,
Why primary keys are essential for creating logical standby database? I have created a logical standby database on testing basis without having primary keys on most of the tables and it's working fine. I have not event put my main DB in force logging mode.

I have not event put my main DB in force logging mode. This is because, redo log files or standby redo logfiles transforms into set of sql statements to update logical standby.
Have you done any DML operations with nologging options and do you notice any errors in the alert.log? I just curious to know.
But I wanted to know that, while system tablespace in hot backup mode,In the absence of both a primary key and a nonnull unique constraint/index, all columns of bounded size are logged as part of the UPDATE statement to identify the modified row. In other words, all columns except those with the following types are logged: LONG, LOB, LONG RAW, object type, and collections.
Jaffar

Query to return list of all missing primary key ids from table T1

I found this query online that returns a start and stop for a range of all missing primary key id values from table T1. However i want to rewrite this query to return a whole list of all the missing primary key ids and not a start and stop range. any help plz?
select strt, stp
from (select m.id + 1 as strt,
(select min(id) - 1 from T1 x where x.id > m.id) as stp
from T1 m left outer join T1 r on m.id = r.id - 1 where r.id is null)x where stp is not null

with t as
          select 1 as id from dual union all
          select 2 as id from dual union all
          select 3 as id from dual union all
          select 5 as id from dual union all
          select 8 as id from dual union all
          select 10 as id from dual union all
          select 11 as id from dual union all
          select 20 as id from dual
select id_start + level missing_id
from (
         select id id_start,
                 nullif(lead(id) over(order by id) - 1, id) id_end
           from t
start with id_end is not null
connect by prior id_start = id_start
         and prior dbms_random.random is not null
         and level <= id_end - id_start
MISSING_ID
         4
         6
         7
         9
        12
        13
        14
        15
        16
        17
        18
MISSING_ID
        19
12 rows selected.Or:
with t as
          select 1 as id from dual union all
          select 2 as id from dual union all
          select 3 as id from dual union all
          select 5 as id from dual union all
          select 8 as id from dual union all
          select 10 as id from dual union all
          select 11 as id from dual union all
          select 20 as id from dual
select id_start + level - 1 missing_id
   from (
          select min(id) id_start,
                  max(id) id_end
            from t
   connect by level <= id_end - id_start
minus
select id
   from t
MISSING_ID
         4
         6
         7
         9
        12
        13
        14
        15
        16
        17
        18
MISSING_ID
        19
12 rows selected.SY.

Diff b/w primary key and unique key?

what is the diff b/w primary key and unique key?

Hi,
With respect to functionality both are same.
But in ABAP we only have Primary key for the Database tables declared in the Data Dictionary.
Unique is generally is the term used with declaring key's for internal tables.
Both primary and Unique keys can identify one record of a table.
Regards,
Sesh

Access path difference between Primary Key and Unique Index

Hi All,
Is there any specific way the oracle optimizer treats Primary key and Unique index differently?
Oracle Version
SQL> select * from v$version;
BANNER
Oracle Database 11g Enterprise Edition Release 11.2.0.3.0 - 64bit Production
PL/SQL Release 11.2.0.3.0 - Production
CORE    11.2.0.3.0      Production
TNS for IBM/AIX RISC System/6000: Version 11.2.0.3.0 - Production
NLSRTL Version 11.2.0.3.0 - Production
SQL> Sample test data for Normal Index
SQL> create table t_test_tab(col1 number, col2 number, col3 varchar2(12));
Table created.
SQL> create sequence seq_t_test_tab start with 1 increment by 1 ;
Sequence created.
SQL> insert into t_test_tab select seq_t_test_tab.nextval, round(dbms_random.value(1,999)) , 'B'||round(dbms_random.value(1,50))||'A' from dual connect by level < 100000;
99999 rows created.
SQL> commit;
Commit complete.
SQL> exec dbms_stats.gather_table_stats(USER_OWNER','T_TEST_TAB',cascade => true);
PL/SQL procedure successfully completed.
SQL> select col1 from t_test_tab;
99999 rows selected.
Execution Plan
Plan hash value: 1565504962
| Id | Operation         | Name       | Rows | Bytes | Cost (%CPU)| Time     |
|   0 | SELECT STATEMENT |            | 99999 |   488K|    74   (3)| 00:00:01 |
|   1 | TABLE ACCESS FULL| T_TEST_TAB | 99999 |   488K|    74   (3)| 00:00:01 |
Statistics
          1 recursive calls
          0 db block gets
       6915 consistent gets
        259 physical reads
          0 redo size
    1829388 bytes sent via SQL*Net to client
      73850 bytes received via SQL*Net from client
       6668 SQL*Net roundtrips to/from client
          0 sorts (memory)
          0 sorts (disk)
      99999 rows processed
SQL> create index idx_t_test_tab on t_test_tab(col1);
Index created.
SQL> exec dbms_stats.gather_table_stats('USER_OWNER','T_TEST_TAB',cascade => true);
PL/SQL procedure successfully completed.
SQL> select col1 from t_test_tab;
99999 rows selected.
Execution Plan
Plan hash value: 1565504962
| Id | Operation         | Name       | Rows | Bytes | Cost (%CPU)| Time     |
|   0 | SELECT STATEMENT |            | 99999 |   488K|    74   (3)| 00:00:01 |
|   1 | TABLE ACCESS FULL| T_TEST_TAB | 99999 |   488K|    74   (3)| 00:00:01 |
Statistics
          1 recursive calls
          0 db block gets
       6915 consistent gets
          0 physical reads
          0 redo size
    1829388 bytes sent via SQL*Net to client
      73850 bytes received via SQL*Net from client
       6668 SQL*Net roundtrips to/from client
          0 sorts (memory)
          0 sorts (disk)
      99999 rows processed
SQL> Sample test data when using Primary Key
SQL> create table t_test_tab1(col1 number, col2 number, col3 varchar2(12));
Table created.
SQL> create sequence seq_t_test_tab1 start with 1 increment by 1 ;
Sequence created.
SQL> insert into t_test_tab1 select seq_t_test_tab1.nextval, round(dbms_random.value(1,999)) , 'B'||round(dbms_random.value(1,50))||'A' from dual connect by level < 100000;
99999 rows created.
SQL> commit;
Commit complete.
SQL> exec dbms_stats.gather_table_stats('USER_OWNER','T_TEST_TAB1',cascade => true);
PL/SQL procedure successfully completed.
SQL> select col1 from t_test_tab1;
99999 rows selected.
Execution Plan
Plan hash value: 1727568366
| Id | Operation         | Name        | Rows | Bytes | Cost (%CPU)| Time     |
|   0 | SELECT STATEMENT |             | 99999 |   488K|    74   (3)| 00:00:01 |
|   1 | TABLE ACCESS FULL| T_TEST_TAB1 | 99999 |   488K|    74   (3)| 00:00:01 |
Statistics
          1 recursive calls
          0 db block gets
       6915 consistent gets
          0 physical reads
          0 redo size
    1829388 bytes sent via SQL*Net to client
      73850 bytes received via SQL*Net from client
       6668 SQL*Net roundtrips to/from client
          0 sorts (memory)
          0 sorts (disk)
      99999 rows processed
SQL> alter table t_test_tab1 add constraint pk_t_test_tab1 primary key (col1);
Table altered.
SQL> exec dbms_stats.gather_table_stats('USER_OWNER','T_TEST_TAB1',cascade => true);
PL/SQL procedure successfully completed.
SQL> select col1 from t_test_tab1;
99999 rows selected.
Execution Plan
Plan hash value: 2995826579
| Id | Operation            | Name           | Rows | Bytes | Cost (%CPU)| Time     |
|   0 | SELECT STATEMENT     |                | 99999 |   488K|    59   (2)| 00:00:01 |
|   1 | INDEX FAST FULL SCAN| PK_T_TEST_TAB1 | 99999 |   488K|    59   (2)| 00:00:01 |
Statistics
          1 recursive calls
          0 db block gets
       6867 consistent gets
          0 physical reads
          0 redo size
    1829388 bytes sent via SQL*Net to client
      73850 bytes received via SQL*Net from client
       6668 SQL*Net roundtrips to/from client
          0 sorts (memory)
          0 sorts (disk)
      99999 rows processed
SQL> If you see here the even though statistics were gathered,
     * In the 1st table T_TEST_TAB, the table is still using FULL table access after creation of index.
     * And in the 2nd table T_TEST_TAB1, table is using PRIMARY KEY as expected.
Any comments ??
Regards,
BPat

Thanks.
Yes, ignored the NOT NULL part.Did a test and now it is working as expected
SQL> create table t_test_tab(col1 number not null, col2 number, col3 varchar2(12));
Table created.
SQL>
create sequence seq_t_test_tab start with 1 increment by 1 ;SQL>
Sequence created.
SQL> insert into t_test_tab select seq_t_test_tab.nextval, round(dbms_random.value(1,999)) , 'B'||round(dbms_random.value(1,50))||'A' from dual connect by level < 100000;
99999 rows created.
SQL> commit;
Commit complete.
SQL> exec dbms_stats.gather_table_stats('GREP_OWNER','T_TEST_TAB',cascade => true);
PL/SQL procedure successfully completed.
SQL> set autotrace traceonly
SQL> select col1 from t_test_tab;
99999 rows selected.
Execution Plan
Plan hash value: 1565504962
| Id | Operation         | Name       | Rows | Bytes | Cost (%CPU)| Time     |
|   0 | SELECT STATEMENT |            | 99999 |   488K|    74   (3)| 00:00:01 |
|   1 | TABLE ACCESS FULL| T_TEST_TAB | 99999 |   488K|    74   (3)| 00:00:01 |
Statistics
          1 recursive calls
          0 db block gets
       6912 consistent gets
          0 physical reads
          0 redo size
    1829388 bytes sent via SQL*Net to client
      73850 bytes received via SQL*Net from client
       6668 SQL*Net roundtrips to/from client
          0 sorts (memory)
          0 sorts (disk)
      99999 rows processed
SQL> create index idx_t_test_tab on t_test_tab(col1);
Index created.
SQL> exec dbms_stats.gather_table_stats('GREP_OWNER','T_TEST_TAB',cascade => true);
PL/SQL procedure successfully completed.
SQL> select col1 from t_test_tab;
99999 rows selected.
Execution Plan
Plan hash value: 4115006285
| Id | Operation            | Name           | Rows | Bytes | Cost (%CPU)| Time     |
|   0 | SELECT STATEMENT     |                | 99999 |   488K|    63   (2)| 00:00:01 |
|   1 | INDEX FAST FULL SCAN| IDX_T_TEST_TAB | 99999 |   488K|    63   (2)| 00:00:01 |
Statistics
          1 recursive calls
          0 db block gets
       6881 consistent gets
          0 physical reads
          0 redo size
    1829388 bytes sent via SQL*Net to client
      73850 bytes received via SQL*Net from client
       6668 SQL*Net roundtrips to/from client
          0 sorts (memory)
          0 sorts (disk)
      99999 rows processed
SQL>

Difference between primary key and primary index

Dear All,
Hi... .Could you pls tell me the difference between primary key and primary index.
Thanks...

Hi,
Primary Key : It is one which makes an entry of the field unique.No two distinct rows in a table can have the same value (or combination of values) in those columns.
Eg: first entry is 111, if you again enter value 111 , it doesnot allow 111 again. similarly for the strings or characters or numc etc. Remember that for char or numc or string 'NAME' is not equal to 'name'.
Primary Index: this is related to the performance .A database index is a data structure that improves the speed of operations in a table. Indices can be created using one or more columns, providing the basis for both rapid random lookups and efficient ordering of access to records. The disk space required to store the index is typically less than the storage of the table (since indices usually contain only the key-fields according to which the table is to be arranged, and excludes all the other details in the table), yielding the possibility to store indices into memory from tables that would not fit into it. In a relational database an index is a copy of part of a table. Some databases extend the power of indexing by allowing indices to be created on functions or expressions. For example, an index could be created on upper(last_name), which would only store the uppercase versions of the last_name field in the index.
In a database , we may have a large number of records. At the time of retrieving data from the database based on a condition , it is a burden to the db server. so whenever we create a primary key , a primary index is automatically created by the system.
If you want to maintain indices on other fields which are frequently used in where condition then you can create secondary indices.
Reward points if helpful.
Thanks,
Sirisha..

What is the diffrence between Row id and primary key ?

dear all
my question is about creating materialized views parameters (With Rowid and
With Primary kry)
my master table contains a primary key
and i created my materialized view as follow:
CREATE MATERIALIZED VIEW LV_BULLETIN_MV
TABLESPACE USERS
NOCACHE
LOGGING
NOCOMPRESS
NOPARALLEL
REFRESH FAST ON DEMAND
WITH PRIMARY KEY
AS
SELECT
BCODE ID, BTYPE BTYPE_ID,
BDATE THE_DATE,SYMBOL_CODE STOCK_CODE,
BHEAD DESC_E, BHEADARB DESC_A,
BMSG TEXT_E, BMSGARB TEXT_A,
BURL URL, BTIME THE_TIME
FROM BULLETIN@egid_sefit;
I need to know is there a diffrence between using (with row id) and (with primary key) on the performance of the query?

Hi again,
fast refreshing complex views based on rowids, according to the previous subject.
(You're example shows that) are not possible.
Complex remote (replication) snapshots cannot be based on Rowid too.
for 10.1
http://download-west.oracle.com/docs/cd/B14117_01/server.101/b10759/statements_6002.htm#sthref5054
for 10.2
http://download-uk.oracle.com/docs/cd/B19306_01/server.102/b14200/statements_6002.htm#sthref6873
So I guess (didn't check it) that this applies ONLY to replication snapshots.
This is not documented clearly though (documentation bug ?!)
Documentation states that the following is generally not possible with Rowid MVIEWS:
Distinct or aggregate functions
GROUP BY or CONNECT BY clauses
Subqueries
Joins
Set operations
Rowid materialized views are not eligible for fast refresh after a master table reorganization until a complete refresh has been performed.
The main purpose of my statements was to try to give a few tips how to avoid common problems with this complex subject, like for example: being able to CREATE an MVIEW with fast refresh clause does not really guarantee that it will refresh fast in the long run (reorganisation, partition changes) if ROWID based, further the rowid mviews have limitations according to the documentation (no group by, no connect by, link see above) plus fast refresh means only to use filter columnns of the mview logs, plus for aggregates you need additional count (*) pseudo columns.
kind regards
Karsten

Primary key vs Secondary key - why would a rpt hit one as to the other?

Post Author: kevans
CA Forum: Data Connectivity and SQL
Here's an issue that surfaced when using CRW10, happens with XI as well, but not an issue with CRW8 - each one is hitting the same SQL Server db.
I discovered something today and I'm not sure if this might be the road to a solution, however, I don't know enough about SQL Server and/or Crystal. First, my reports seem fairly simple in nature, I don't think I'm pulling a million rows of data, maybe but doubt it. So I run report ABC and I see blocking issues in SQL Server Enterprise Mgr. If I run report XYZ that isn't too much different than ABC, I do not see blocking issues. Hmm, what could be different? In SQL-Mgr when I look at the SPID info generated by the report I can see the tables the report is referencing and below is what I discovered.
The one difference I see is under the "Index" column - the report blocking shows "XPKcall_req" where call_req is the table I'm pulling from. The report that IS NOT blocking shows call_req_x0. I checked with our dba and he wasn't sure, other than to say XPK is the primary key index. Okay, then why is one report hitting the primary key index (whatever that is) and the other isn't? In Crystal I'm not sure how to tell it to stop doing this, I tried shaking my finger and yelling but like my kids this does little.
Any ideas, with the report that is?

Post Author: kevans
CA Forum: Data Connectivity and SQL
Here's an issue that surfaced when using CRW10, happens with XI as well, but not an issue with CRW8 - each one is hitting the same SQL Server db.
I discovered something today and I'm not sure if this might be the road to a solution, however, I don't know enough about SQL Server and/or Crystal. First, my reports seem fairly simple in nature, I don't think I'm pulling a million rows of data, maybe but doubt it. So I run report ABC and I see blocking issues in SQL Server Enterprise Mgr. If I run report XYZ that isn't too much different than ABC, I do not see blocking issues. Hmm, what could be different? In SQL-Mgr when I look at the SPID info generated by the report I can see the tables the report is referencing and below is what I discovered.
The one difference I see is under the "Index" column - the report blocking shows "XPKcall_req" where call_req is the table I'm pulling from. The report that IS NOT blocking shows call_req_x0. I checked with our dba and he wasn't sure, other than to say XPK is the primary key index. Okay, then why is one report hitting the primary key index (whatever that is) and the other isn't? In Crystal I'm not sure how to tell it to stop doing this, I tried shaking my finger and yelling but like my kids this does little.
Any ideas, with the report that is?

Performance: index vs. primary key

For reasons beyond my control, I have an Oracle database with no primary keys. Fields that would likely be primary keys, however, are indexed.
Is there any reason to believe that database performance will improve if I do add primary keys?
If yes, why?
Thank you!
-Brent

Primary keys provide unique values and an in built index on thecolumn. Since the fields are indexed converting them to primary keys shall not affect the performance.Yes, if u want unique values they can be defined as Primary Keys.
However if these fields are VARCHAR2 with large size then an index will not improve the performance. You can look at creating new PK as numeric fields with a Sequence.
<BLOCKQUOTE><font size="1" face="Verdana, Arial">quote:</font><HR>Originally posted by Brent Christensen ([email protected]):
For reasons beyond my control, I have an Oracle database with no primary keys. Fields that would likely be primary keys, however, are indexed.
Is there any reason to believe that database performance will improve if I do add primary keys?
If yes, why?
Thank you!
-Brent<HR></BLOCKQUOTE>
null

Primary key index not working in a select statment

Hi ,
I'm doing a :
select *
from my_table
where B = v1 and
A = v2 ;
where A and B are the primary key of the table, in that table the primary key index is there and the order of the primary key definition is A first and then B.
While testing this statment in my database the Explain Plan shows that it is using the index ok but when
runninng in client database it is not using it becasue of the order (i think), is this something configurable that I need to ask to my DBA ?
The solution I found was to do the select with a hint wich fix the problem , but I'm curious about why is working in my dadabase and not in the client database
thanks in advance .
oracle version 11g

This is the forum for SQL Developer (Not for general SQL/PLSQL questions). Your question would be better asked in the SQL and PL/SQL forum.
Short answer: The execution plan used will depend on optimizer settings and table/index statistics. For example if the table has very few rows it may not bother using the index.

Descending primary key

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